Next Article in Journal
Molecular Mechanism Pathways of Natural Compounds for the Treatment of Non-Alcoholic Fatty Liver Disease
Next Article in Special Issue
Chitosan Enhances Low-Dosage Difenoconazole to Efficiently Control Leaf Spot Disease in Pseudostellaria heterophylla (Miq.) Pax
Previous Article in Journal
A Lamellar Zn-Based Coordination Polymer Showing Increasing Photoluminescence upon Dehydration
Previous Article in Special Issue
Recent Developments and Applications of Microbial Levan, A Versatile Polysaccharide-Based Biopolymer
 
 
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Review

Recent Progress in 1,2-cis glycosylation for Glucan Synthesis

1
RIKEN, Cluster for Pioneering Research, Saitama 351-0198, Japan
2
Department of Chemical Science and Engineering, Tokyo Institute of Technology, Tokyo 152-8552, Japan
3
Graduate School of Science, Osaka University, Osaka 560-0043, Japan
4
School of Pharmaceutical Sciences (Shenzhen), Shenzhen Campus of Sun Yat-sen University, Shenzhen 518107, China
*
Authors to whom correspondence should be addressed.
Molecules 2023, 28(15), 5644; https://doi.org/10.3390/molecules28155644
Submission received: 5 June 2023 / Revised: 30 June 2023 / Accepted: 2 July 2023 / Published: 25 July 2023
(This article belongs to the Special Issue Polysaccharide-Based Biopolymer: Recent Development and Applications)

Abstract

:
Controlling the stereoselectivity of 1,2-cis glycosylation is one of the most challenging tasks in the chemical synthesis of glycans. There are various 1,2-cis glycosides in nature, such as α-glucoside and β-mannoside in glycoproteins, glycolipids, proteoglycans, microbial polysaccharides, and bioactive natural products. In the structure of polysaccharides such as α-glucan, 1,2-cis α-glucosides were found to be the major linkage between the glucopyranosides. Various regioisomeric linkages, 1→3, 1→4, and 1→6 for the backbone structure, and 1→2/3/4/6 for branching in the polysaccharide as well as in the oligosaccharides were identified. To achieve highly stereoselective 1,2-cis glycosylation, including α-glucosylation, a number of strategies using inter- and intra-molecular methodologies have been explored. Recently, Zn salt-mediated cis glycosylation has been developed and applied to the synthesis of various 1,2-cis linkages, such as α-glucoside and β-mannoside, via the 1,2-cis glycosylation pathway and β-galactoside 1,4/6-cis induction. Furthermore, the synthesis of various structures of α-glucans has been achieved using the recent progressive stereoselective 1,2-cis glycosylation reactions. In this review, recent advances in stereoselective 1,2-cis glycosylation, particularly focused on α-glucosylation, and their applications in the construction of linear and branched α-glucans are summarized.

1. Introduction

Stereoselective synthesis of 1,2-cis glycosides is one of the most challenging issues in the chemical synthesis of glycans [1,2,3,4,5,6,7]. Various 1,2-cis glycosides in nature have been found as α-glucoside and β-mannoside in glycoproteins, glycolipids, proteoglycans, microbial polysaccharides, and bioactive natural products. In the structure of polysaccharides such as α-glucan, 1,2-cis α-glucosides were found to be the major linkage between the glucopyranosides. Various regioisomeric linkages, 1→3, 1→4, and 1→6 for backbone structure, and 1→2/3/4/6 for branching in the polysaccharide as well as in the oligosaccharides were identified.

α-D-glucans

α-D-glucan is a homopolysaccharide and a simple polymer of α-D-glucopyranoside (α-D-Glcp) [8,9]. D-Glucose, the component of the D-glucans, is photosynthesized in plants and widespread in nature and exists in its D-glucopyranose form in α-D-glucans [10]. The most common and linear example of α-D-glucan is (1→4)-α-D-glucan (amylose), which plays an essential role as an energy source for metabolism [11]. The chain length of amylose is known to be in the order of 500–6000 glucose units, depending on its botanical origin. Three crystalline forms of amylose, A-, B-, and C- (a mixture of A and B) granules [12], containing random and short helical segments, have been reported. Crystallized structures were found in the V form [13,14,15], and each segment composed of six glucose residues formed a left-handed, single-stranded helical structure [16]. Branched (1→4)-α-D-glucans are called amylopectin and glycogen, the analogues of starch for energy storage in plants and animals, fungi, and bacteria, respectively. The structures of amylopectin and glycogen are well known to be more compact than that of linear amylose. (1→4)-α-D-glucan is biologically synthesized by glucosyltransferase [17,18,19,20] and amylosucrase (sucrose-1,4-α-glucan glucosyltransferase [21,22,23,24] and (1→4)-α-D-glucan branching enzymes [25,26,27,28,29,30]).
α-D-glucans also have extremely complex structural diversity according to various regioisomers, making non-branched and branched α-D-glucans with (1→6)-, (1→4)-, (1→3)-, and (1→2)-glycosidic linkages and molecular masses according to the degree of polymerization (Figure 1). The α-D-glucans have been obtained from various species, listed in Table 1 [31,32,33,34,35,36].
Regioisomeric linear (1→6)-α-D-glucans (isomaltosides) were isolated from Amillariella tabescens and Sarcodon aspratus [37,38,39]. A dextran [40] obtained from lactic acid bacteria, such as Lactobacillus, Leuconostoc, Weissella, and Streptococcus, has a (1→6)-α-D-glucan backbone with up to 50% branching as α-(1→3), α-(1→4), or α-(1→2) linkages. Several glucosyl transferase (Gtf) enzymes synthesize dextrans with [41,42] and without branching [43,44,45,46,47,48]. The complex branched structures make the dextrans effective energy storage molecules that release D-glucose slowly via enzymatic hydrolysis [49,50,51,52,53].
Linear (1→3)-α-D-glucan (pseudonigan) was identified from Aspergillus niger [48] as a storage polysaccharide [54]. To the best of our knowledge, a linear (1→2)-α-D-glucan has not yet been identified. The (1→3)-α-D-glucans are major components of the cell wall of filamentous fungi [55,56,57] and dimorphic yeasts [58,59,60,61] and are synthesized via the primer for (1→3)-α-D-glucans by intracellular amylases. The structural analysis of (1→3)-α-D-glucan was reported and it was mentioned that three crystalline forms I–III of (1→3)-α-D-glucan were detected and interconverted via dehydration and hydration reactions [32,62]. Various biological functions of (1→3)-α-D-glucan were investigated such as immunological activity via Toll-like receptor 4 (TLR4) [63,64,65], which has been shown in the case of (1→4)-α-D-glucans as well as β-D-glucans [66].
More complex branching structures have been discovered in various linear glucans [33,67,68]. From dextran, NRRL B1397, an α-D-Glc-(1→2)-α-D-Glc-(1→6)-D-Glc structure [69,70,71,72,73] was identified and the D-Glc-(1→2)-branching moiety was found to be an α-glucoside to tricholomal (1→4)-α-D-glucan [74].
The most common and linear example of a stereoisomeric β-D-glucans is cellulose, composed of β-D-Glcp, which plays a fundamental role as a structural component of the cell wall [75,76]. As physiologically active biological response modifiers (BRMs), the structure of glucans and the biological activity relationship of β-D-glucans have been reported to be adjuvants in bacterial, viral, or protozoan infections, and potent antitumor drugs, depending on the molecular weight, degree of branching, conformation, and intermolecular associations of glucans [76,77,78,79,80,81]. In the case of the synthesis of β-D-glucans, a common methodology such as stereoselective β-D-glucopyranosylation via the effect of neighboring group participation from the 2-O-acyl group can be effectively used [82,83,84].
Table 1. Various α-D-glucans in nature.
Table 1. Various α-D-glucans in nature.
LinkageNameSourceRef.
LinearSide Chain
(1→4)-α-Amylose Mycobacterium tuberculosis[85,86]
(1→4)-α-Amylose Streptomyces venezuelae[87]
(1→4)-α-Amylose Fusicoccum amygdale[88]
(1→4)-α-AmyloseAgaricus blazei[89]
(1→4)-α-AmylosePleurotus ostreatus[84]
(1→4)-α-StarchRice bran[90]
(1→4)-α(1→6)-αGlycogenSaccharomyces cerevisiae[91]
(1→4)-α(1→6)-αGlycogenAgaricus bisporus[92]
(1→4)-α(1→6)-αGlycogenCordyceps sinensis[93]
(1→4)-α(1→6)-αGlycogenCoprinus comatus[94]
(1→4)-α(1→6)-αGlycogenFlammulina velutipes[95]
(1→4)-α(1→6)-αGlycogenGastrodia elata Bl[96]
(1→4)-α(1→6)-αGlycogenLonicera japonica Thunb[97]
(1→4)-α(1→6)-αGlycogenActinidia chinensis[98]
(1→4)-α(1→2); (1→6)-αGlycogenTricholoma matsutake[71]
(1→4)(1→6)-α-ReuteranLactobacillus reuteri[99]
(1→4)(1→6)-α-PullulanAureobasidium pullulans
Cyttaria harioti
Tremella mesenterica
[100]
(1→4)(1→6)-α-PullulanTremella mesenterica[101]
(1→3)-α-PseudonigeranAspergillus flavipes
Aspergillus flavus
Aspergillus fumigatus
Aspergillus ochraceus
[102]
(1→3)-α--Aspergillus fumigatus[103,104,105,106]
(1→3)-α-PseudonigeranAspergillus nidulans[107,108,109]
(1→3)-α--Aspergillus niger[110,111]
(1→3)-α-PseudonigeranAspergillus niger NNRL 326[111]
(1→3)-α--Aspergillus wentii[112]
(1→3)-α-PseudonigeranBlastomyces dermatiditis (yeast form)[113,114]
(1→3)-α-PseudonigeranEupenicillium crustaceum[111]
(1→3)-α-PseudonigeranFusarium oxysporum[111]
(1→3)-α-PseudonigeranFusicoccum amygdale[88]
(1→3)-α-PseudonigeranHistoplasma capsulatum[115]
(1→3)-α-PseudonigeranHistoplasma farciminosum[116]
(1→3)-α-PseudonigeranParacoccidioides brasiliensis[117]
(1→3)-α-PseudonigeranPenicillium brevi-compactum
Penicillium decumbens
[102]
(1→3)-α-PseudonigeranPenicillium expansum[118]
(1→3)-α-PseudonigeranPenicillium chrysogenum[119]
(1→3)-α-PseudonigeranPoria cocos[120]
(1→3)-α-PseudonigeranAgrocybe cylindracea[121]
(1→3)-α--Amanita muscaria[122]
(1→3)-α-PseudonigeranArmillaria mellea[123]
(1→3)-α-PseudonigeranCryptococcus albidus[124]
(1→3)-α-PseudonigeranCryptococcus terreus[124]
(1→3)-α-PseudonigeranGanoderma lucidum[125]
(1→3)-α-PseudonigeranGanoderma tsugae[126]
(1→3)-α--Laetiporus sulphureus[127]
(1→3)-α-PseudonigeranLentinus edodes[128]
(1→3)-α-PseudonigeranPiptoporus betulinus[127]
(1→3)-α-PseudonigeranPleurotus ostreatus[36]
(1→3)-α-PseudonigeranPleurotus eryngii[88]
(1→3)-α-PseudonigeranPolyporus tumulosus[129]
(1→3)-α-PseudonigeranSchizophyllum commune[130]
(1→3)-α-PseudonigeranTremella mesenterica[101]
(1→3)-α(1→6)-αMutanLactobacillus reuteri
Streptococcus mutans
Streptococcus salivarius
Streptococcus sownei
[131,132]
(1→3)(1→4)-α-NigeranAspergillus niger var.awamori
Aspergillus niger var.unknowy
some Aspergillus species
[133]
(1→3)(1→4)-α--Aspergillus wentii[112]
(1→3)(1→4)-α--Cladosporium herbarum[134]
(1→3)(1→4)-α-ElsinanElsinoe leucospila[135]
(1→3)(1→4)-α--Neurospora crassa[136]
(1→3)(1→4)-α-NigeranFew other Penicillium species[137]
(1→3)(1→4)-α--Schizosaccharomyces pombe[124]
(1→3)(1→4)-α-NigeranArmillaria mellea[123]
(1→3)(1→4)-α--Coriolus versicolor[138]
(1→3)(1→4)-α-PseudonigeranCryptococcus neoformans[139]
(1→3)(1→4)-α-PseudonigeranLaetiporus sulphureus[127]
(1→3)(1→4)-α-PseudonigeranLentinus edodes[128]
(1→3)(1→4)-α-IsolicheninCetraria richardsonii[140]
(1→3)(1→4)-α-IsolicheninCetraria islandica[140]
(1→3)(1→4)-α-IsolicheninLetharia vulpine[140]
(1→3)(1→4)-α-EverniinEvernia prunastri[141,142]
(1→3)(1→4)-α-NigeranParmelia carperata
Parmelia cetrarioides
Ramalina species,
Cladonia species
[140]
(1→3)(1→4)-α-IsolicheninAlectoria sarmentosa
Alectoria sulcate
Cetraria species
Usnea species
Parmelia species
[141,142]
(1→3)(1→6)-α(1→3)-αAlternanLeuconostoc mesenteroides
Streptococcus salivarius
[131,132]
(1→3)(1→6)-α--Termitomyces eurhizus[45]
(1→3)(1→4)(1→6)-α-AcroscyphanAcroscyphus sphaerophoroides[141,142]
(1→6)-α--Coriolus versicolor[138]
(1→6)-α--Sarcodon aspratus[143]
(1→6)-α--Termitomyces eurhizus[45]
(1→6)-α-StarchBanana[144]
(1→6)-α-StarchDimocarpus longan Lour cv Shixia[145]
(1→6)-α-StarchPueraria lobata (willed) ohwi[146]
(1→6)-α-StarchIpomea batatus[147]
(1→6)-α 1--Chlorella vulgaris[148]
(1→6)-α(1→3)-α-Lobelia chinensis[149]
(1→6)-α(1→2); (1→3); (1→4)-αDextranLactobacillus species
Leuconostoc dextranicum
Leuconostoc mesenteroides
Streptococcus mutans
Weissella species
[131,132]
(1→2)-α ---
1 sulfated glucan.

2. 1,2-cis glycosylation

Stereoselective O-glycosylation is a key step in the assembly of biologically relevant oligosaccharides. The target oligosaccharide contains 1,2-cis- or 1,2-trans-configurated O-glycosidic linkages to the C-2–O bond of the non-reducing side residue of the glycoside. The 1,2-cis linkages, such as α-glucopyranoside, α-galactopyranoside, β-mannopyranoside, β-rhamnopyranoside, and other glycosides, are found in natural glycans, including glycoconjugate such as glycoproteins, glycolipids, proteoglycans, microbial polysaccharides, and glycosylated natural products. Controlling the stereoselectivity in the formation of 1,2-cis glycosides is extremely challenging in synthetic chemistry, as in the case of α-gluco (2-equatorial)- and β-manno (2-axial)-type glycoside formations, although the method for the 1,2-trans isomers was developed by using the effect of neighboring group participation from theC-2 acyl group as the first choice of the chemist. Various methods using inter- [150,151,152,153,154,155] and intra- [156,157,158] molecular procedures have been developed for the stereoselective synthesis of 1,2-cis glycosides [153,159], depending on the acceptor molecules [160,161], and further developments have been reported in recent years [162,163,164,165].
The 2-O-ether-protected glycosyl donors predominantly afford the axial glycosides via stereoelectronic effects [166,167,168,169,170,171,172,173] (Figure 2). Using this methodology, 1,2-cis gluco-type pyranosides were selectively obtained. However, the selectivity is not predictable, mainly because of the many controversial results reported from a variety of examinations using many types of donors suitably optimized to the demand of their targets. Based on basic observations, the solvent effect [174,175,176,177,178,179,180], the concentration effect [181,182,183,184,185], and other factors [186,187,188], including a very recent approach using an SN2-predicting, leaving group enhanced by a coordinating acceptor [189,190], were also accepted as factors for the stereoselectivity of glycosylation. This review focuses on two effective and stereoselective methods for glucan synthesis: the use of C2-o-tosylamide (TsNH)-benzyl (TAB) ether for bimodal glycosylation [191,192,193] and ZnI2-mediated 1,2-cis glycosylation [194].

2.1. Bimodal Glycosylation Approach

2.1.1. Bimodal Glycosylation Approach for 1,2-cis α-glucosylation

Because of the structural diversity of glucans, a unified strategy for the assembly of pure glucans is yet to be developed. For the stereocontrolled synthesis of both α- and β-glycosides, a general strategy that applies to the construction of all types of glucans by exploiting a bimodal [195,196,197,198,199] glucosyl donor equipped with C2-o-TAB ether [200,201,202,203,204] by the simple switching of the reaction conditions was developed in our laboratory [191,192] (Scheme 1). The synthesis of the glycosyl trichloroacetimidate donor with C2-O-TAB ether was carried out through a five-step transformation from the C2-OH of the thioglycoside derivative via C2-O-ether formation with o-azidobenzyl bromide [205,206] and NaH, reduction in the azide moiety by triphenylphosphine, and tosylation of the resultant amine. This was followed by the hydrolysis of the thioglycoside and subsequent treatment with trichloroacetonitrile in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) (Scheme 1a).
The selective formation of β-glucosides was achieved when the activation of trichloroacetimidate was carried out by bis(trifluoromethanesulfonyl)imide (Tf2NH) [207,208,209,210] in propionitrile (EtCN) at low temperatures (−40 to −78 °C) (β-directing conditions). Using the same glucosyl donor, an alternative activation by triflic acid (TfOH) in Et2O under diluted conditions at room temperature predominantly provided α-glucosides as the major product (α-directing conditions) (Scheme 1b). After glucosylation, the selective liberation of the 3-, 4-, or 6-OH functionality in the presence of the TAB group at the C2 position and deprotection of the TAB group to liberate the 2-hydroxy group allowed for further glycosylations. The versatility of the bimodal glucosylation method was demonstrated by effectively assembling fragments of natural and non-natural glucans [191].
When the PhSO2 group of an equatorially oriented TAB group at the 2-O-position interacts with the glycosyl cation through neighboring group participation in the presence of Tf2NH in EtCN, β-glycosides are predominantly formed (Scheme 1c). The stereodirecting effects of the TAB group have been explained by the contribution of hydrogen bonding between tosylamide and benzylic oxygen, forming a quasi-bicyclic form, such as the 2-phthalimide (NPhth) group as a 1,2-trans directing group [211,212,213]. The activation of the donor moiety to initiate the formation of the oxocarbenium ion results in subsequent NGP by the sulfonamide oxygen to provide β-glycosides. Contrary to 1,2-trans-glycosylation, in ether solvents, the disruption of the intramolecular hydrogen bonding may result in the interaction with the incoming acceptor via intermolecular hydrogen bonding, controlling the 1,2-cis attack to afford α-glucosides selectively. Reactions using the perbenzylglucosyl trichloroacetimidate donor without the NHTs group in the presence of Tf2NH in EtCN provided the corresponding glycosides with diminished stereoselectivity (α/β = 11/ 89 compared with β-only for 6a), whereas the stereoselectivity was similar (α/β = 83/17) to 6a (84/16) in the presence of TfOH in Et2O [191]. These results also support the proposed mechanism.

2.1.2. Bimodal Glycosyl Donor Approach for Application to 1,2-cis α-galactosylation and 1,2-cis-β-mannosylation

The bimodal α- and β-glycosylations were simply applied to the stereoselective synthesis of both α- and β-galactosides using a bimodal galactosyl donor with C2-O-TAB ether by the simple switching of the α- and β-directing reaction conditions, respectively, optimized for glucosylation [191]. The galactosyl donor has equatorial C2-O-TAB, which should similarly induce α- and β-selectivity as the glucosyl donor (Scheme 2a).
As in the case of bimodal α- and β-glucosylation, it was found that the hydrogen bond donating ability of the TsNH group of the 2-O-TAB group caused an interaction with the incoming alcohol (ROH), thereby leading to 1,2-cis-selective glycosylation, as mentioned before. Next, 2-O-TAB was used for 1,2-cis-selective mannosylation [214]. In addition, by changing the reaction conditions that disrupt the intermolecular hydrogen bonding, the selective formation of the 1,2-trans-α-glycoside is possible (Scheme 2b). Although the construction of α-mannosyl linkages can be achieved by neighboring group participation or through the exploitation of stereoelectronic effects, the β-linkage of mannoside is challenging to construct stereoselectively [215]. Well-established methodologies for β-mannoside synthesis include direct glycosylation with 4,6-O-benzylidene protected donors [216,217,218,219,220,221,222] and indirect methodologies, including intramolecular aglycon delivery (IAD) [156,223,224,225,226,227,228,229], intermolecular H-bond-mediated aglycone delivery [230], stereochemical inversion of β-gluco or β-galacto glycosides [231,232,233,234,235], and anomeric O-alkylations [236].
An overstoichiometric amount of the Zn2+ salt (2 equiv.) is required for β-mannosylation using a mannosyl donor with an imidate or phosphite as the leaving groups. Under these conditions, oxygen atoms at the 2- and 3-position coordinate with Zn2+, cleaving the intramolecular hydrogen bonding [237,238] (Scheme 2c). Afterward, the liberated NH group will be able to interact with an incoming nucleophile in an intermolecular fashion, reversing the stereocontrolling effect of the TAB group. The use of Cu(OTf)2 in toluene, especially at elevated temperatures with the same phosphite donor, afforded the α-isomer predominantly. The application of this bimodal mannosyl donor to the synthesis of all possible stereoisomers of trisaccharide D-Man-(1→2)-D-Man-(1→6)-D-Glc [239,240,241,242,243] was achieved.

2.2. ZnI2-mediated Stereoselective Glycosylation Approach

2.2.1. ZnI2-mediated 1,2-cis α-glucosylation

As shown in the case of bimodal α- and β-mannosylations using the 2-O-TAB group that interacted with/without the acceptor (ROH), the effect of Zn2+ salt (2 equiv.) was revealed for β-mannosylation, using the mannosyl donor with imidate or phosphite as the leaving group. It has been observed that the Zn2+ cation not only activates the donor leaving group but also coordinates with oxygens at the 2- and 3- positions to induce the effective interaction of TAB with an incoming nucleophile during 1,2-cis-β-mannosylation [214]. Combined with the enhancement of the fixed conformation of the pyranose ring by the 4,6-O-cyclic protection reported by Crich [244,245], a simple ZnI2-mediated procedure involving activation and direction to control the stereoselectivity for glucosylation has been developed as a novel general synthetic strategy for the construction of α-glucoside as one of the most abundant 1,2-cis-glycosidic bonds in nature [194]. To the best of our knowledge, the effective use of ZnI2 for 1,2-cis glycosylation using a simple trichloroacetimidate donor has not been reported until recently. Using various acceptors, ZnI2-mediated α-glucosylation was demonstrated using 4,6-O-naphthylidene (NapCH<)-protected donors (6a) to demonstrate its versatility and effectiveness (Figure 3, Scheme 3(a-1)). The modular synthesis of various α-glucans with both linear and branched backbone structures using this simple approach was successfully achieved, as described in Section 3.2.1.
In addition to the experimental investigations and theoretical calculations, the ZnI2-mediated 1,2-cis glycosylation was analyzed (Scheme 3(a-2)) [194]. Theoretically, ZnI2 activates the anomeric leaving groups on the donor molecule as Lewis acids and enhances glycosyl iodide formation. Subsequent activation of glycosyl iodide by another ZnI2 leads to an intermediate that is also coordinated with the first ZnI2, which effectively coordinates with both hydroxyl groups on the acceptor, forming a six-membered structure with a trichloroacetimidate ion and the O-2 of the donor. Subsequent stereocontrolled nucleophilic attacks from the same side to the O-2 of the donor afford a 1,2-cis linkage, which then dissociates to the desired products.

2.2.2. ZnI2-mediated 1,2-cis β-mannosylation, and cis β-galactosylation

As we have successfully developed a ZnI2-directed general strategy for 1,2-cis α-glucosylation using a 4,6-O-naphthylidene and 2-O-benzyl (Bn)-protected glucosyl donors with excellent stereoselectivity [194], the ZnI2-mediated 1,2-cis glycosylation strategy has been applied to other linkages, such as 1,2-cis β-mannosides [217] and 1,2-cis α-galactosides [246]. In recent years, various methods have been developed [247,248,249] for stereoselective glycosylation to obtain more difficult 1,2-cis linkages with equatorial glycosides found in the core structure of the N-glycans [250,251,252,253,254,255,256,257]. The ZnI2-directed strategy can be extended to the 4,6-O-tether and 2-O-benzyl-protected mannosyl trichloroacetimidate donors [217], promising an alternative β-mannosylation methodology via a similar 1,2-cis stereoselectivity to 1,2-cis α-glucosylation (Figure 3, Scheme 3(b-1)). ZnI2-promoted mannosylation has also been used to synthesize the core structure of N-glycan effectively. The ZnI2 coordination with both a hydroxyl group on the acceptor and the O-2 of the donor after glycosyl iodide formation, followed by anomerization from the β- to α-isomer and the subsequent activation of α-glycosyl iodide by the second ZnI2, afforded a 1,2-cis β-mannosidic linkage [217] (Scheme 3(b-2)).
In contrast, glycosylation with 4,6-O-naphthylidene and 2-O-benzyl-protected galactosyl trichloroacetimidate donor (6aGal) under ZnI2 activation conditions resulted in 1,2-trans β-galactosylation [246] (Figure 3, Scheme 3(c-1)). Based on the experimental and theoretical investigations, β-galactosylation should be promoted by the dual roles of the proposed zinc cations as the activator and mediator of the structural restriction-enhanced cis stereodirecting intermolecular interaction, unexpectedly from the 4- or 6-position of the 4,6-O-naphthylidene-protected galactosyl donor, and not from the 2-position, as in the 1,2-cis cases of glucosylation and mannosylation (Scheme 3(c-2)).

3. Recent Progress on the Synthesis of α-glucans

3.1. Application of the Bimodal Glycosylation Approach for Stereoselective 1,2-cis α-glucosylation toward the Synthesis of α-glucans

3.1.1. Bimodal Glycosylation Approach for the Synthesis of Linear α-glucans

The construction of (1→2/3/4/6)-α-linkages of glucosides is a challenge because it is restricted by the 1,2-cis-stereocontrolled glycosylation methodologies and impacts assembly strategies [258]. The glucosyl donor equipped with a TAB group at the C2 position was examined for further elongation at that position after the deprotection of the TAB group of the glycosylation products to liberate the 2-hydroxy group [191]. The conversion was performed in four steps: (1) Boc protection, (2) deprotection of the Ts group via Mg treatment, (3) Boc deprotection, and (4) treatment with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ). Both α- and β-glycosides were converted into 2-hydroxy α- and β-D-Glc-(1→6)-α-D-Glc-OMe, respectively. (Scheme 4a,b). The resultant disaccharide acceptors were treated with C2-o-TAB-protected bimodal glucosyl donor under α- and β-directing conditions to afford four possible D-Glc-(1→2)-D-Glc-(1→6)-α-D-Glc-OMe derivatives (12), including α-D-Glc-(1→2)-α-D-Glc-(1→6)-α-D-Glc-OMe (α,α-12) [69,70,71,72,73]. This TAB approach should be applicable in the particular case of (1→2)-branched (1→3/4/6)-α-D-glycans or motifs.
Figure 1 glucan fragment, a 6-hydroxy α-D-Glc-(1→6)-α-D-Glc-OMe derivative was prepared using 4,6-O-naphthylidene-3-O-triisopropylsilyl (TIPS)-2-O-(o-TAB)-D-glucopyranosyl trichloroacetimidate (1f*) and methyl 2,3,4-tri-O-benzyl-D-glucopyranoside (4) as the donor and acceptor, respectively (Scheme 5a) [193]. Several iterations of glycosylation under α-directing conditions and subsequent reductive ring-opening reactions to regioselectively liberate the 6-hydroxy group afforded methyl α-isomaltotetraoside [α-D-Glc-(1→6)]4-OMe (16).
The iterations of the glycosylation of allyl 4,6-O-benzylidene-2-O-(o-TAB)-D-glucopyranoside (19) with 4,6-O-naphthylidene-3-O-triisopropylsilyl-2-O-(o-TAB)-D-glucopyranosyl trichloroacetimidate (1f*) under α-directing conditions and subsequent deprotection of the TIPS group to liberate the 3-hydroxy group afforded the tetrasaccharide fragment (22) of linear (1→3)-α-D-glucan named pseudonigeran from Aspergillus niger (Scheme 5b).
The iterations of glycosylation of methyl 2,3,6-tri-O-benzyl-D-glcopyranoside (23) with 4,6-O-benzylidene-3-O-benzyl-2-O-(o-TAB)-D-glucopyranosyl trichloroacetimidate (1f**) was performed under α-directing conditions. Furthermore, the subsequent regioselective reductive ring-opening reaction to liberate the 4-hydroxy group afforded the pentasaccharide derivative (26) with the backbone structure of linear (1→4)-α-D-glucan (Scheme 5c), which was also elongated with 4,6-O-naphthylidene-3-O-triisopropylsilyl-2-O-(o-TAB)-D-glucopyranosyl trichloroacetimidate (1f*) under α-directing conditions to afford a hexasaccharide derivative (Scheme 5d).

3.1.2. Bimodal Glycosylation Approach for the Synthesis of Branched α-glucans

For the construction of a branched α-glucan fragment, the α-(1→3)-branch in the linear (1→6)-α-D-glucan backbone, one of the components of dextran, was examined via the initial introduction of the α-(1→3)-branch (Scheme 5a, branching). The disaccharide obtained via the glycosylation of 4,6-O-naphthylidene-3-O-triisopropylsilyl-2-O-(o-TAB)-D-glucopyranosyl trichloroacetimidate (1f*) with methyl 2,3,4-tri-O-benzyl-D-glucopyranoside (4) under α-directing conditions, followed by the subsequent deprotection of the TIPS group, afforded the corresponding 3-OH disaccharyl acceptor (14). The subsequent α-selective glucosylation of the resultant acceptor with 3,4,6-tri-O-benzyl-2-O-(o-TAB)-D-glucopyranosyl trichloroacetimidate (1f) under α-directing conditions followed by a reductive ring-opening reaction to liberate the 6-hydroxy group and successive glycosylation under α-directing conditions afforded the tetrasaccharide fragment of a branched α-(1→6)-linked (1→3)-α-D-glucan (18) after hydrogenolysis.
The introduction of an α-(1→6)-branch into the linear (1→4)-α-D-glucan backbone was also examined via double α-glucosylation of the diol acceptor. After the synthesis of tetrasaccharide fragment (26) of linear (1→4)-α-D-glucan, deprotection of the benzylidene group by TFA in CH2Cl2 afforded the 4,6-diol (24) at the nonreducing D-glucose residue (Scheme 5c). The α-glucosylation of the resultant diol acceptor with 3 equiv. of the 4,6-O-benzylidene-3-O-benzyl-2-O-(o-TAB)-D-glucopyranosyl trichloroacetimidate donor (1f**) under α-directing conditions afforded a fully protected branched hexasaccharide fragment (30) in one pot (Scheme 5e, branching).

3.2. Application of ZnI2-mediated Stereoselective 1,2-cis α-glucosylation toward the Synthesis of α-glucans

3.2.1. ZnI2-mediated Glycosylation Approach for the Synthesis of Linear α-glucans

An alternative method for the synthesis of linear (1→3)-α-D-glucan, which constitutes the Pseudonigeran isolated from Aspergillus niger, has been shown using the ZnI2-directed α-glucosylation methodology [194]. After the first ZnI2-directed (1→3)-α-glucosylation between 6b and 31, the deprotection of the C-3-O-TIPS group of the resultant α-linked disaccharide (32) with TBAF in tetrahydrofuran (THF) afforded the corresponding disaccharide (33) with a C-3 hydroxy group (Scheme 6a). ZnI2-promoted glucosylation of the disaccharide acceptor (33) with the glucosyl donor (6b) gave the α,α-linked trisaccharide with high α-selectivity in a 71% yield. Repeating the deprotection and glucosylation steps yields the α,α,α-linked tetrasaccharide (34) stereoselectively, which was followed by the global deprotections via the desilylation and hydrogenolysis of 35 to complete the total synthesis of nigerotetraoside (37), a fragment of linear (1→3)-α-D-glucan. The desilylation of C-3-O-TIPS on tetrasaccharide (34) provided the acceptor (35), while the treatment of 34 with PdCl2 in methanol, followed by a reaction with CCl3CN and DBU, afforded the corresponding tetrasaccharyl trichloroacetimidate donor (36). Subsequent [4 + 4] coupling between the donor (36) and acceptor (35) with the ZnI2-promoted methodology under optimized conditions accomplished the synthesis of the target α-D-glucan nigerooctaoside (38) (Scheme 6b), suggesting the powerful synthetic applicability of the ZnI2-promoted glucosylation to oligosaccharide donors and acceptors with multiple repeating units (tetrasaccharides) in a fragment condensation strategy for assembling higher-molecular-weight glucans.

3.2.2. ZnI2-mediated Glycosylation Approach for the Synthesis of Branched α-glucans

The versatility of the ZnI2-promoted glucosylation method has been shown by synthesizing branched α-glucan tetrasaccharides, such as (1→6)-α-branched (1→4)-α-D-glucan and (1→3)-α-branched (1→6)-α-D-glucan [194] (Scheme 6c,d).
The synthesis of α-(1→6)-branched (1→4)-α-D-glucan (46) was initiated by the stereoselective ZnI2-mediated glucosylation of the 4-OH acceptor 23 with 2-O-benzyl-4,6-O-benzylidene-3-O-2-naphthylmethyl (NAP)-D-glucopyranosyl donor (6a) for an α-(1→4)-linked disaccharide (39), followed by the liberation of C-6-OH using the selective reduction protocol of 4,6-O-benzylidene acetal with BH3·THF and trimethylsilyl trifluoromethanesulfonate (TMSOTf). The second ZnI2-mediated α-(1→6)-glucosylation of the resultant acceptor (40) with the donor (6a) provided the linear α-D-glucan trisaccharide fragment (41) stereoselectively. The subsequent hydrolysis of 4,6-O-benzylidene acetal using TFA in DCM afforded 4,6-diol (42), and a treatment of the resultant 4,6-diol of 42 with NaH and BnBr, followed by the selective removal of the NAP ether of 43 with DDQ, afforded the C-4-OH (44) at the residue in the middle of the same trisaccharide linkage (Scheme 6c). The resultant acceptor (44) was then glycosylated with a donor (6a) for branching under the ZnI2-mediated α-glucosylation conditions to provide the desired fully protected tetrasaccharide (45), which was followed by hydrogenolysis to complete the total synthesis of the branched α-glucan (46).
To introduce the (1→3)-branching to the (1→6)-α-D-glucan backbone, (1→6)-α-D-glucan trisaccharide derivative (47) was obtained by the stereoselective ZnI2-mediated glucosylation of the 6-OH acceptor (4) with donor (6a) followed by reductive ring-opening of naphthylidene acetal under BH3·THF and TMSOTf conditions, and the second stereoselective ZnI2-mediated glucosylation with the 3-O-TIPS-protected donor (6b). The liberation of the C-3-OH group by deprotection of the TIPS group of 47 with TBAF/AcOH afforded the corresponding 48, and the third ZnI2-promoted α-glucosylation with the donor (6a) afforded the desired (1→3)-α-(1→6)-α-D-glucan tetrasaccharide (18) after hydrogenolysis via 49 with exclusive α-stereoselectivity (Scheme 6d). For the target branching structure, installing a functionality on the donor or acceptor moiety for the chemoselective liberation of the hydroxy group at a suitable position is required for the design of the synthesis, as shown here.

4. Conclusions

In this review, recent advances in stereoselective 1,2-cis glycosylation, focusing on α-glucosylation by bimodal glycosylation using o-TsNHbenzyl ether and ZnI2-mediated α-glucosylation, and their applications in the construction of various types of linear branched glycans, are discussed. These enable a systematic investigation of the glucan structure-biological activity relationships with a whole series of possible structural isomers that would become simpler and more facile. In addition, recent approaches toward cyclic α-glucans such as cyclodextrins with a small ring size (down to three glucose residues in the ring) used conformationally counterbalanced donors between equatorial- and axial-rich forms. The automated α-glucan synthesis of up to 20 glucose residues was reported by Yamada [259] and by Seeberger [260], respectively. As Yu reported very recently [199], the synthesis and structural analysis of α-glucans could be possible with MD calculations to allow a more reliable estimation of the van der Waals volumes of α-glucans. Further structural investigations are valuable and may enable various applications, such as biotechnology for medicine and cosmetics, functional foods, drug delivery, and immunological responses.

Author Contributions

Conceptualization, writing—original draft preparation, A.I. and F.D.; writing—review and editing, A.I., K.T., Y.I., H.C. and F.D.; project administration, finalization, revisons for publications, A.I. and F.D.; supervision, funding acquisition, A.I., Y.I. and F.D. All authors have read and agreed to the published version of the manuscript.

Funding

This work was partly supported by JSPS KAKENHI for Scientific Research (JP19H00929 and JP18K05345 to A.I. and JP22H02196 to Y.I.). This work was supported partly by the Fundamental Research Funds for the Province Natural Science Fund of Guangdong (No. 2021A1515010189 to F.D.).

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

Not applicable.

Acknowledgments

We would like to thank Masayo Ohara for her kind technical assistance.

Conflicts of Interest

The authors declare no conflict of interest.

References

  1. Andreana, P.R.; Crich, D. Guidelines for O-Glycoside Formation from First Principles. ACS Cent. Sci. 2021, 7, 1454–1462. [Google Scholar] [CrossRef]
  2. Gangoiti, J.; Corwin, S.F.; Lamothe, L.M.; Vafiadi, C.; Hamaker, B.R.; Dijkhuizen, L. Synthesis of novel α-glucans with potential health benefits through controlled glucose release in the human gastrointestinal tract. Crit. Rev. Food Sci. Nutr. 2020, 60, 123–146. [Google Scholar] [CrossRef]
  3. Shivatare, S.S.; Wong, C.-H. Synthetic Carbohydrate Chemistry and Translational Medicine. J. Org. Chem. 2020, 85, 15780–15800. [Google Scholar] [CrossRef]
  4. Loh, C.C.J. Exploiting non-covalent interactions in selective carbohydrate synthesis. Nat. Rev. Chem. 2021, 5, 792–815. [Google Scholar] [CrossRef]
  5. Wang, L.; Overkleeft, H.S.; van der Marel, G.A.; Codée, J.D.C. Reagent Controlled Stereoselective Synthesis of α-Glucans. J. Am. Chem. Soc. 2018, 140, 4632–4638. [Google Scholar] [CrossRef] [Green Version]
  6. Wang, L.; Zhang, Y.; Overkleeft, H.S.; van der Marel, G.A.; Codée, J.D.C. Reagent Controlled Glycosylations for the Assembly of Well-Defined Pel Oligosaccharides. J. Org. Chem. 2020, 85, 15872–15884. [Google Scholar] [CrossRef]
  7. Inuki, S.; Tabuchi, H.; Matsuzaki, C.; Yonejima, Y.; Hisa, K.; Kimura, I.; Yamamoto, K.; Ohno, H. Chemical Synthesis and Evaluation of Exopolysaccharide Fragments Produced by Leuconostoc mesenteroides Strain NTM048. Chem. Pharm. Bull. 2022, 70, 155–161. [Google Scholar] [CrossRef] [PubMed]
  8. Shetty, P.R.; Batchu, U.R.; Buddana, S.K.; Sambasiva Rao, K.; Penna, S. A comprehensive review on α-D-Glucans: Structural and functional diversity, derivatization and bioapplications. Carbohydr. Res. 2021, 503, 108297. [Google Scholar] [CrossRef] [PubMed]
  9. Wang, G.-L.; Li, J.-Y.; Wang, Y.; Chen, Y.; Wen, Q.-L. Extraction, Structure and Bioactivity of Polysaccharides from Tricholoma matsutake (S. Ito et Imai) Singer (Review). Appl. Biochem. Microbiol. 2022, 58, 375–381. [Google Scholar] [CrossRef]
  10. Stephens, Z.; Wilson, L.F.L.; Zimmer, J. Diverse mechanisms of polysaccharide biosynthesis, assembly and secretion across kingdoms. Curr. Opin. Struct. Biol. 2023, 79, 102564. [Google Scholar] [CrossRef] [PubMed]
  11. Thitipraphunkul, K.; Uttapap, D.; Piyachomkwan, K.; Takeda, Y. A comparative study of edible canna (Canna edulis) starch from different cultivars. Part II. Molecular structure of amylose and amylopectin. Carbohydr. Polym. 2003, 54, 489–498. [Google Scholar] [CrossRef]
  12. Sarko, A.; Wu, H.-C.H. The Crystal Structures of A-, B- and C-Polymorphs of Amylose and Starch. Starch 1978, 30, 73–78. [Google Scholar] [CrossRef]
  13. Helbert, W.; Chanzy, H. Single crystals of V amylose complexed with n-butanol or n-pentanol: Structural features and properties. Int. J. Biol. Macromol. 1994, 16, 207–213. [Google Scholar] [CrossRef] [PubMed]
  14. Bail, P.L.; Rondeau, C.; Buleon, A. Structural investigation of amylose complexes with small ligands: Helical conformation, crystalline structure and thermostability. Int. J. Biol. Macromol. 2005, 35, 1–7. [Google Scholar] [CrossRef] [PubMed]
  15. Rappenecker, G.; Zugenmaier, P. Detailed refinement of the crystal structure of Vh-amylose. Carbonhydr. Res. 1981, 89, 11–19. [Google Scholar] [CrossRef]
  16. Zhang, Q.; Lu, Z.; Hu, H.; Yang, W.; Marszalek, P.E. Direct detection of the formation of V-amylose helix by single molecule force spectroscopy. J. Am. Chem. Soc. 2006, 128, 9387–9393. [Google Scholar] [CrossRef] [Green Version]
  17. Sivak, M.N.; Preiss, J. (Eds.) Starch: Basic Science to Biotechnology. In Advances in Food and Nutrition Research; Academic Press: Cambridge, MA, USA, 1998; Volume 41. [Google Scholar]
  18. Buléon, A.; Colonna, P.; Planchot, V.; Ball, S. Starch granules: Structure and biosynthesis. Int. J. Biol. Macromol. 1998, 23, 85–112. [Google Scholar] [CrossRef] [Green Version]
  19. Wang, T.L.; Bogracheva, T.Y.; Hedley, C.L. Starch: As simple as A, B, C? J. Exp. Bot. 1998, 49, 481–502. [Google Scholar] [CrossRef] [Green Version]
  20. James, M.G.; Robertson, D.S.; Myers, A.M. Characterization of the maize gene sugary1, a determinant of starch composition in kernels. Plant Cell 1995, 7, 417–429. [Google Scholar]
  21. Hehre, E.J.; Hamilton, D.M.; Carlson, A.S. Synthesis of a polsaccharide of the starch glycogen class from sucrose by a cell-free, bacterial enzyme system (amylosucrase). J. Biol. Chem. 1949, 177, 267–279. [Google Scholar] [CrossRef]
  22. Potocki de Montalk, G.; Remaud-Simeon, M.; Willemot, R.-M.; Sarçabal, P.; Planchot, V.; Monsan, P. Amylosucrase from Neisseria polysaccharea: Novel catalytic properties. FEBS Lett. 2000, 471, 219–223. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  23. Kim, B.-S.; Kim, H.-S.; Hong, J.-S.; Huber, K.C.; Shim, J.-H.; Yoo, S.-H. Effects of amylosucrase treatment on molecular structure and digestion resistance of pre-gelatinised rice and barley starches. Food Chem. 2013, 138, 966–975. [Google Scholar] [CrossRef] [PubMed]
  24. Jung, Y.-S.; Hong, M.-G.; Park, S.-H.; Lee, B.-H.; Yoo, S.-H. Biocatalytic Fabrication of α-Glucan-Coated Porous Starch Granules by Amylolytic and Glucan-Synthesizing Enzymes as a Target-Specific Delivery Carrier. Biomacromolecules 2019, 20, 4143–4149. [Google Scholar] [CrossRef] [PubMed]
  25. Li, Y.; Ren, J.; Liu, J.; Sun, L.; Wang, Y.; Liu, B.; Li, C.; Li, Z. Modification by α-D-glucan branching enzyme lowers the in vitro digestibility of starch from different sources. Int. J. Biol. Macromol. 2018, 107, 1758–1764. [Google Scholar] [CrossRef]
  26. Park, I.; Park, M.; Yoon, N.; Cha, J. Comparison of the Structural Properties and Nutritional Fraction of Corn Starch Treated with Thermophilic GH13 and GH57 α-Glucan Branching Enzymes. Foods 2019, 8, 452. [Google Scholar] [CrossRef] [Green Version]
  27. Ban, X.; Dhoble, A.S.; Li, C.; Gu, Z.; Hong, Y.; Cheng, L.; Holler, T.P.; Kaustubh, B.; Li, Z. Bacterial 1,4-α-glucan branching enzymes: Characteristics, preparation and commercial applications. Crit. Rev. Biotechnol. 2020, 40, 380–396. [Google Scholar] [CrossRef]
  28. Yu, L.; Kong, H.; Gu, Z.; Li, C.; Ban, X.; Cheng, L.; Hong, Y.; Li, Z. Two 1,4-α-glucan branching enzymes successively rearrange glycosidic bonds: A novel synergistic approach for reducing starch digestibility. Carbohydr. Polym. 2021, 262, 117968. [Google Scholar] [CrossRef]
  29. Xu, T.; Li, Z.; Gu, Z.; Li, C.; Cheng, L.; Hong, Y.; Ban, X. The N-terminus of 1,4-α-glucan branching enzyme plays an important role in its non-classical secretion in Bacillus subtilis. Food Biosci. 2023, 52, 102491. [Google Scholar] [CrossRef]
  30. Lambré, C.; Baviera, J.M.B.; Bolognesi, C.; Cocconcelli, P.S.; Crebelli, R.; Gott, D.M.; Grob, K.; Lampi, E.; Mengelers, M.; Mortensen, A.; et al. Safety evaluation of the food enzyme 1,4-α-glucan branching enzyme from the non-genetically modified Geobacillus thermodenitrificans strain TRBE14. EFSA J. 2023, 21, e07834. [Google Scholar]
  31. Carbonero, E.R.; Montai, A.V.; Woranovicz-Barreira, S.; Gorin, P.A.J.; Lacomini, M. Polysaccharides of lichenized fungi of three Cladina spp.: Significance as chemotypes. Phytochemistry 2002, 61, 681–686. [Google Scholar] [CrossRef]
  32. Synytsya, A.; Novak, M. Structural analysis of glucans. Ann. Transl. Med. 2014, 2, 17–31. [Google Scholar]
  33. Naessens, M.; Cerdobbel, A.; Soetaert, W.; Vandamme, E.J. Leuconostoc dextransucrase and dextran: Production, properties and applications. J. Chem. Technol. Biotechnol. 2005, 80, 845–860. [Google Scholar] [CrossRef]
  34. Zhong, X.; Wang, G.; Fang, S.; Zhou, S.; Ishiwata, A.; Cai, H.; Ding, F. Immunomodulatory Effect and Biological Significance of β-Glucans. Pharmaceutics 2023, 15, 1615. [Google Scholar] [CrossRef]
  35. Okuyama, M.; Saburi, W.; Mori, H.; Kimura, A. α-Glucosidases and α-1,4-Glucan Lyases: Structures, Functions, and Physiological Actions. Cell. Mol. Life Sci. 2016, 73, 2727–2751. [Google Scholar] [CrossRef]
  36. Synytsya, A.; Novák, M. Structural Diversity of Fungal Glucans. Carbohydr. Polym. 2013, 92, 792–809. [Google Scholar] [CrossRef] [PubMed]
  37. Luo, X.; Xu, X.; Yu, M.; Yang, Z.; Zheng, L. Characterisation and immunostimulatory activity of an α-(1→6)-D-glucan from the cultured Armillariella tabescens mycelia. Food Chem. 2008, 111, 357–363. [Google Scholar] [CrossRef] [PubMed]
  38. Han, X.Q.; Wu, X.M.; Chai, X.Y.; Chen, D.; Dai, H.; Dong, H.L.; Ma, Z.Z.; Gao, X.M.; Tu, P.F. Isolation, characterization and immunological activity of a polysaccharide from the fruit bodies of an edible mushroom, Sarcodon aspratus (Berk.) S. Ito. Food. Res. Int. 2011, 44, 489–493. [Google Scholar] [CrossRef]
  39. Painter, T.J. Details of the fine structure of nigeran revealed by the kinetics of its oxidation by periodate. Carbohydr. Res. 1990, 200, 403–408. [Google Scholar] [CrossRef]
  40. Pasteur, L. On the viscous fermentation and the butyrous fermentation. Bull. Soc. Chim. Paris 1861, 11, 30–31. [Google Scholar]
  41. Leemhuis, H.; Pijning, T.; Dobruchowska, J.M.; van Leeuwen, S.S.; Kralj, S.; Dijkstra, B.W.; Dijkhuizen, L. Glucansucrases: Three-dimensional structures, reactions, mechanism, α-glucan analysis and their implications in biotechnology and food applications. J. Biotechnol. 2013, 163, 250–272. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  42. van Hijum, S.A.F.T.; Kralj, S.; Ozimek, L.K.; Dijkhuizen, L.; van Geel-Schutten, I.G.H. Structure-function relationships of glucansucrase and fructansucrase enzymes from lactic acid bacteria. Microbiol. Mol. Biol. Rev. 2006, 70, 157–176. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  43. Simpson, C.L.; Cheetham, N.W.H.; Jacques, N.A. Four glucosyltransferases, gtfJ, gtfK, gtfL and gtfM, from Streptococcus salivarius ATCC 25975. Microbiology 1995, 141, 1451–1460. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  44. Kang, H.-K.; Oh, J.-S.; Kim, D. Molecular characterization and expression analysis of the glucansucrase DSRWC from Weissella cibaria synthesizing a α(1→6) glucan. FEMS Microbiol. Lett. 2009, 292, 33–41. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  45. Mondal, S.; Chakraborty, I.; Pramanik, M.; Rout, D.; Islam, S.S. Structural studies of water-soluble polysaccharides of an edible mushroom, Termitomyces eurhizus. A reinvestigation. Carbohydr. Res. 2004, 339, 1135–1140. [Google Scholar] [CrossRef] [PubMed]
  46. Purama, R.K.; Goswami, P.; Khan, A.T.; Goyal, A. Structural analysis and properties of dextran produced by Leuconostoc mesenteroides NRRL B-640. Carbohydr. Polym. 2009, 76, 30–35. [Google Scholar] [CrossRef]
  47. Loesche, W.J. Role of Streptococcus mutans in human dental decay. Microbiol. Rev. 1986, 50, 353. [Google Scholar] [CrossRef]
  48. He, Q.; Kobayashi, K.; Kusumi, R.; Kimura, S.; Enomoto, Y.; Yoshida, M.; Kim, U.-J.; Wada, M. In vitro Synthesis of Branchless Linear (1→6)-α-D-Glucan by Glucosyltransferase K: Mechanical and Swelling Properties of Its Hydrogels Crosslinked with Diglycidyl Ethers. ACS Omega 2020, 5, 31272–31280. [Google Scholar] [CrossRef]
  49. Rosenfeld, E.L.; Lukomskaya, I.S. The splitting of dextran and isomaltose by animal tissues. Clin. Chim. Acta 1957, 2, 105–114. [Google Scholar] [CrossRef]
  50. Wang, R.; Dijkstra, P.J.; Karperien, M. Dextran. Biomaterials from Nature for Advanced Devices and Therapies; Wiley: Hoboken, NJ, USA, 2016; pp. 307–319. [Google Scholar]
  51. Hong, M.-G.; Yoo, S.-H.; Lee, B.-H. Effect of highly branched α-glucans synthesized by dual glycosyltransferases on the glucose release rate. Carbohydr. Polymer 2022, 278, 119016. [Google Scholar] [CrossRef]
  52. Banerjee, A.; Bandopadhyay, R. Use of dextran nanoparticle: A paradigm shift in bacterial exopolysaccharide based biomedical applications. Int. J. Biol. Macromol. 2016, 87, 295–301. [Google Scholar] [CrossRef]
  53. Lamothe, L.M.; Francey, C.; Lerea-Antes, J.S.; Rytz, A.; D’Urzo, C.; Delodder, F.; Piccardi, N.; Curti, D.; Murciano Martinez, P.; Darimont, C.; et al. Effects of α-D-glucans with alternating 1,3/1,6 α-D-glucopyranosyl linkages on postprandial glycemic response in healthy subjects. Carbohydr. Polym. Technol. Appl. 2022, 4, 100256. [Google Scholar] [CrossRef]
  54. Zonneveld, B.J.M. The Significance of α-1,3-glucan of the cell wall and α-1,3-glucanase for cleistothecium development. Biochim. Biophys. Acta. 1972, 273, 174–187. [Google Scholar] [CrossRef] [PubMed]
  55. Johnston, I.R. The composition of the cell wall of Aspergillus niger. Biochem. J. 1965, 96, 651–658. [Google Scholar] [CrossRef] [PubMed]
  56. Zonneveld, B.J.M. Biochemical analysis of the cell wall of Aspergillus nidulans. Biochim. Biophys. Acta. 1971, 249, 506–514. [Google Scholar] [CrossRef]
  57. Yoshimi, A.; Miyazawa, K.; Abe, K. Function and Biosynthesis of Cell Wall α-1,3-Glucan in Fungi. J. Fungi 2017, 3, 63. [Google Scholar] [CrossRef] [PubMed]
  58. Van der Kaaij, R.M.; Janecek, S.; van der Maarel, M.J.E.C.; Dijkhuizen, L. Phylogenetic and biochemical characterization of a novel cluster of intracellular fungal α-amylase enzymes. Microbiology 2007, 153, 4003–4015. [Google Scholar] [CrossRef] [Green Version]
  59. Marion, C.L.; Rappleye, C.A.; Engle, J.T.; Goldman, W.E. An α-(1,4)-amylase is essential for α-(1,3)-glucan production and virulence in Histoplasma capsulatum. Mol. Microbiol. 2006, 62, 970–983. [Google Scholar] [CrossRef]
  60. Camacho, E.; Sepulveda, V.E.; Goldman, W.E.; San-Blas, G.; Niño-Vega, G.A. Expression of Paracoccidioides brasiliensis AMY1 in a Histoplasma capsulatum amy1 mutant, relates an α-(1,4)-amylase to cell wall α-(1,3)-glucan synthesis. PLoS ONE 2012, 7, e50201. [Google Scholar] [CrossRef] [Green Version]
  61. Koizumi, A.; Miyazawa, K.; Ogata, M.; Takahashi, Y.; Yano, S.; Yoshimi, A.; Sano, M.; Hidaka, M.; Nihira, T.; Nakai, H.; et al. Cleavage of α-1,4-glycosidic linkages by the glycosylphosphatidylinositol-anchored α-amylase AgtA decreases the molecular weight of cell wall α-1,3-glucan in Aspergillus oryzae. Front. Fungal Biol. 2023, 3, 1061841. [Google Scholar] [CrossRef]
  62. Jelsma, J.; Kreger, D.R. Polymorphism in crystalline (1→3)-α-D-glucan from fungal cell-walls. Carbohydr. Res. 1979, 71, 51–64. [Google Scholar] [CrossRef]
  63. Złotko, K.; Wiater, A.; Waśko, A.; Pleszczyńska, M.; Paduch, R.; Jaroszuk-Ściseł, J.; Bieganowski, A. A Report on Fungal (1→3)-α-D-glucans: Properties, Functions and Application. Molecules 2019, 24, 3972. [Google Scholar] [CrossRef] [Green Version]
  64. Moreno-Mendieta, S.; Guillén, D.; Hernández-Pando, R.; Sánchez, S.; Rodríguez-Sanoja, R. Potential of glucans as vaccine adjuvants: A review of the α-glucans case. Carbohydr. Polym. 2017, 165, 103–114. [Google Scholar] [CrossRef]
  65. Patra, S.; Maity, P.; Chakraborty, I.; Sen, I.K.; Ghosh, D.; Rout, D.; Bhanja, S.K. Structural studies of immunomodulatory (1→3)-, (1→4)-α glucan from an edible mushroom Polyporus grammocephalus. Int. J. Biol. Macromol. 2021, 168, 649–655. [Google Scholar] [CrossRef] [PubMed]
  66. Chen, R.; Xu, J.; Wu, W.; Wen, Y.; Lu, S.; El-Seedi, H.R.; Zhao, C. Structure–immunomodulatory activity relationships of dietary polysaccharides. Curr. Res. Food Sci. 2022, 5, 1330–1341. [Google Scholar] [CrossRef] [PubMed]
  67. Zhang, Y.; Kong, H.; Fang, Y.; Nishinari, K.; Phillips, G.O. Schizophyllan: A review on its structure, properties, bioactivities and recent developments. Bioact. Carbohydr. Diet. Fibre 2013, 1, 53–71. [Google Scholar] [CrossRef]
  68. Olennikov, D.N.; Agafonova, S.V.; Rokhin, A.V.; Penzina, T.A.; Borovskii, G.B. Branched glucan from the fruiting bodies of Piptoporus betulinus (Bull.:Fr) Karst. Appl. Biochem. Microbiol. 2012, 48, 65–70. [Google Scholar] [CrossRef]
  69. Pozsgay, V.; Nánási, P.; Neszmélyi, A. Utilisation of the d-glucopyranosyl group as a non-participating group in stereoselective glycosylation: Synthesis of O-α-D-glucopyranosyl-(1→2)-O-α-D-glucopyranosyl-(1→6)-D-glucose. Carbohydr. Res. 1979, 75, 310–313. [Google Scholar] [CrossRef]
  70. Rychener, M.; Bigler, P.; Pfander, H. Synthese und 1H-NMR-Studie der vier unverzweigten peracetylierten β-D-Glucopyranosyl-β-gentiobiosen. Helv. Chim. Acta 1984, 67, 378–385. [Google Scholar] [CrossRef]
  71. Gómez de Segura, A.; Alcalde, M.; Bernabé, M.; Ballesteros, A.; Plou, F.J. Synthesis of methyl α-D-glucooligosaccharides by entrapped dextransucrase from Leuconostoc mesenteroides B-1299. J. Biotechnol. 2006, 124, 439–445. [Google Scholar] [CrossRef] [Green Version]
  72. Brissonnet, Y.; Ladevèze, S.; Tezé, D.; Fabre, E.; Deniaud, D.; Daligault, F.; Tellier, C.; Šesták, S.; Remaud-Simeon, M.; Potocki-Veronese, G.; et al. Polymeric Iminosugars Improve the Activity of Carbohydrate-Processing Enzymes. Bioconjugate Chem. 2015, 26, 766–772. [Google Scholar] [CrossRef]
  73. Ahrazem, O.; Rubio-Moraga, A.; Jimeno, M.; Gómez-Gómez, L. Structural characterization of highly glucosylated crocins and regulation of their biosynthesis during flower development in Crocus. Front. Plant Sci. 2015, 6, 971–985. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  74. Hoshi, H.; Yagi, Y.; Iijima, H.; Matsunaga, K.; Ishihara, Y.; Yasunara, T. Isolation and Characterization of a Novel Immunomodulatory α-Glucan-Protein Complex from the Mycelium of Tricholoma matsutake in Basidiomycetes. J. Agric. Food Chem. 2005, 53, 8948–8956. [Google Scholar] [CrossRef]
  75. Kroon-Batenburg, L.M.; Kroon, J. The crystal and molecular structures of cellulose I and II. Glycoconj. J. 1997, 14, 677–690. [Google Scholar] [CrossRef]
  76. Chawla, P.R.; Bajaj, I.B.; Survase, S.A.; Singhal, R.S. Microbial Cellulose: Fermentative Production and Applications. Food Technol. Biotechnol. 2009, 47, 107–124. [Google Scholar]
  77. Brown, G.D.; Gordon, S. Immune recognition. A new receptor for β-glucans. Nature 2001, 413, 36–37. [Google Scholar] [CrossRef]
  78. Brown, G.D.; Herre, J.; Williams, D.L.; Willment, J.A.; Marshall, A.S.; Gordon, S. Dectin-1 mediates the biological effects of β-glucans. J. Exp. Med. 2003, 197, 1119–1124. [Google Scholar] [CrossRef] [PubMed]
  79. Zipfel, C.; Robatzek, S. Pathogen-Associated Molecular Pattern-Triggered Immunity: Veni, Vidi…? Plant Physiol. 2010, 154, 551–554. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  80. Legentil, L.; Paris, F.; Ballet, C.; Trouvelot, S.; Daire, X.; Vetvicka, V.; Ferrières, V. Molecular Interactions of β-(1→3)-Glucans with Their Receptors. Molecules 2015, 20, 9745–9766. [Google Scholar] [CrossRef]
  81. Adachi, Y. Role of the 1,3-β-D-Glucan Receptor Dectin-1 in Fungal Infection and Activation of Innate and Anti-Tumor Immunity. Trends Glycosci. Glycotechnol. 2007, 19, 195–207. [Google Scholar] [CrossRef] [Green Version]
  82. Fesel, P.H.; Zuccaro, A. β-Glucan: Crucial Component of the Fungal Cell Wall and Elusive MAMP in Plants. Fungal Genet. Biol. 2016, 90, 53–60. [Google Scholar] [CrossRef] [Green Version]
  83. Vetvicka, V.; Vannucci, L.; Sima, P.; Richter, J. Beta Glucan: Supplement or Drug? From Laboratory to Clinical Trials. Molecules 2019, 24, 1251–1268. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  84. Miyagawa, A. Chemical Synthesis of β-(1,3)-Glucan Oligosaccharide and Its Application. Trends Glycosci. Glycotechnol. 2018, 30, E117–E127. [Google Scholar] [CrossRef]
  85. Lemassu, A.; Ortalo-Magne, A.; Bardou, F.; Silve, G.; Laneelle, M.A.; Daffe, M. Extracellular and surface-exposed polysaccharides of non-tuberculous mycobacteria. Microbiol. 1996, 142, 1513–1520. [Google Scholar] [CrossRef] [PubMed]
  86. Ortalo-Magne, A.; Dupont, M.A.; Lemassu, A.; Andersen, A.B.; Gounon, P.; Daffe, M. Molecular composition of the outermost capsular material of the tubercle bacillus. Microbiol. 1995, 141, 1609–1620. [Google Scholar] [CrossRef] [Green Version]
  87. Miah, F.; Bibb, M.J.; Barclay, J.E.; Findlay, K.C.; Bornemann, S. Developmental delay in a Streptomyces venezuelae glgE null mutant is associated with the accumulation of α-maltose 1-phosphate. Microbiol. 2016, 162, 1208–1219. [Google Scholar] [CrossRef]
  88. Buck, K.W.; Obaidah, M.A. The composition of cell wall of Fusicoccum amygdali. Biochem. J. 1971, 125, 461–471. [Google Scholar] [CrossRef] [Green Version]
  89. Mizuno, T.; Hagiwara, T.; Nakamura, T.; Ito, H.; Shimura, K.; Sumiya, T.; Asakura, A. Antitumor activity and some properties of water-soluble polysaccharides from “Himematsutake”, the fruiting body of Agaricus blazei Murill. Agric. Biol. Chem. 1990, 54, 2889–2896. [Google Scholar]
  90. Ghosh, T.; Auerochs, S.; Saha, S.; Ray, B.; Marschall, M. Anti-cytomegalovirus activity of sulfated glucans generated from a commercial preparation of rice bran. Antivir. Chem. Chemother. 2010, 21, 85–95. [Google Scholar] [CrossRef] [Green Version]
  91. Gunja Smith, Z.; Smith, E.E. Evidence for the periplasmic location of glycogen in Saccharomyces. Biochem. Biophys. Res. Commun. 1974, 56, 588–592. [Google Scholar] [CrossRef]
  92. Smiderle, F.R.; Sassaki, G.L.; Van Arkel, J.; Iacomini, M.; Wichers, H.J.; Van Griensven, L.J.L.D. High molecular weight glucan of the medicinal mushroom Agaricus bisporus is an α-glucan that forms complexes with low molecular weight galactan. Molecules 2010, 15, 5818–5830. [Google Scholar] [CrossRef]
  93. Yalin, W.; Cuirong, S.; Yuanjiang, P. Studies on isolation and structural features of a polysaccharide from the mycelium of a Chinese edible fungus (Cordyceps sinensis). Carbohydr. Polym. 2006, 63, 251–256. [Google Scholar] [CrossRef]
  94. Li, B.; Dobruchowska, J.M.; Gerwig, G.J.; Dijkhuizen, L.; Kamerling, J.P. Structural investigation of water-soluble polysaccharides extracted from the fruit bodies of Coprinus comatus. Carbohydr. Polym. 2013, 91, 314–321. [Google Scholar] [CrossRef] [Green Version]
  95. Pang, X.; Yao, W.; Yang, X.; Xie, C.; Liu, D.; Zhang, J.; Gao, X. Purification, characterization and biological activity on hepatocytes of a polysaccharide from Flammulina velutipes mycelium. Carbohydr. Polym. 2007, 70, 291–297. [Google Scholar] [CrossRef]
  96. Qiu, H.; Tang, W.; Tong, X.; Ding, K.; Zuo, J. Structure elucidation and sulfated derivatives preparation of two α-D-glucans from Gastrodia elata and their anti- dengue virus bioactivities. Carbohydr. Res. 2007, 342, 2230–2236. [Google Scholar] [CrossRef]
  97. Wang, P.; Liao, W.; Fang, J.; Liu, Q.; Yao, J.; Hu, M.; Ding, K. A glucan isolated from flowers of Lonicera japonica Thunb. inhibits aggregation and neurotoxicity of Aβ42. Carbohydr. Polym. 2014, 110, 142–147. [Google Scholar] [CrossRef]
  98. Niu, H.; Song, D.; Sun, Y.; Zhang, W.; Mu, H.; Duan, J. Preparation and sulfation of an α-D-glucan from Actinidia chinensis roots and their potential activities. Int. J. Biol. Macromol. 2016, 92, 981–987. [Google Scholar] [CrossRef]
  99. Kralj, S.; Stripling, E.; Sanders, P.; Van Geel-Schutten, G.H.; Dijkhu-izen, L. Highly hydrolytic reuteransucrase from probiotic Lactobacillus reuteri strain ATCC 55730. Appl. Environ. Microbiol. 2005, 71, 3942–3950. [Google Scholar] [CrossRef] [Green Version]
  100. McIntyre, D.D.; Vogel, H.J. Structural studies of pullulan by nuclear magnetic resonance spectroscopy. Starch 1993, 45, 406–410. [Google Scholar] [CrossRef]
  101. Reid, I.D.; Bartnicki-García, S. Cell-wall composition and structure of yeast cells and conjugation tubes of Tremella mesenterica. J. Gen. Microbiol. 1976, 96, 35–50. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  102. Leal, J.A.; Guerrrero, C.; Gomez-Miranda, B.; Prieto, A.; Bernabe, M. Chemical and structural similarities in wall polysaccharides of some Penicillium, Eupenicillium and Aspergillus species. FEMS Microbiol. Lett. 1992, 69, 165–168. [Google Scholar] [CrossRef]
  103. Beauvais, A.; Maubon, D.; Park, S.; Morelle, W.; Tangu, M.; Huerre, M.; Perlin, D.S.; Latgé, J.P. Two α-(1-3) glucan synthases with different functions in Aspergillus fumigatus. Appl. Environ. Microbiol. 2005, 71, 1531–1538. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  104. Beauvais, A.; Bozza, S.; Kniemeyer, O.; Formosa, C.; Formosa, C.; Balloy, V.; Henry, C.; Roberson, R.W.; Dague, E.; Chignard, M.; et al. Deletion of the α-(1,3)-glucan synthase genes induces a restructuring of the conidial cell wall responsible for the avirulence of Aspergillus fumigatus. PLoS Pathog. 2013, 9, e1003716. [Google Scholar] [CrossRef]
  105. Fontaine, T.; Beauvais, A.; Loussert, C.; Thevenard, B.; Fulgsang, C.C.; Ohno, N.; Clavaud, C.; Prevost, M.-C.; Latgé, J.-P. Cell wall α1-3glucans induce the aggregation of germinating conidia of Aspergillus fumigatus. Fungal. Genet. Biol. 2010, 47, 707–712. [Google Scholar] [CrossRef]
  106. Henry, C.; Latgé, J.-P.; Beauvais, A. α1,3 glucans are dispensable in Aspergillus fumigatus. Eukaryot. Cell 2012, 11, 26–29. [Google Scholar] [CrossRef] [Green Version]
  107. Borgia, P.T.; Dodge, C.L. Characterization of Aspergillus nidulans mutants deficient in cell wall chitin or glucan. J. Bacteriol. 1992, 174, 377–383. [Google Scholar] [CrossRef] [Green Version]
  108. He, X.; Li, S.; Kaminskyj, S.G.W. Characterization of Aspergillus nidulans α-glucan synthesis: Roles for two synthases and two amylases. Mol. Microbiol. 2014, 91, 579–595. [Google Scholar] [CrossRef]
  109. Yoshimi, A.; Sano, M.; Inaba, A.; Kokubun, Y.; Fujioka, T.; Mizutani, O.; Hagiwara, D.; Fujikawa, T.; Nishimura, M.; Yano, S.; et al. Functional analysis of the α-1,3-glucan synthase genes agsA and agsB in Aspergillus nidulans: agsB is the major α-1,3-glucan synthase in this fungus. PLoS ONE 2013, 8, e54893. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  110. Damveld, R.A.; vanKuyk, P.A.; Arentshorst, M.; Klis, F.M.; van den Hondel, C.A.M.J.J.; Ram, A.F.J. Expression of agsA, one of five 1,3-α-D-glucan synthase-encoding genes in Aspergillus niger, is induced in response to cell wall stress. Fungal. Genet. Biol. 2005, 42, 165–177. [Google Scholar] [CrossRef]
  111. Horisberger, M.; Lewis, B.A.; Smith, F. Structure of a (1→3)-α-D-glucan (pseudonigeran) of Aspergillus niger NNRL 326 cell wall. Carbohydr. Res. 1972, 23, 183–188. [Google Scholar] [CrossRef]
  112. Choma, A.; Wiater, A.; Komaniecka, I.; Paduch, R.; Pleszczyńska, M.; Szczodrak, J. Chemical characterization of a water insoluble (1→3)-α-D-glucan from an alkaline extract of Aspergillus wentii. Carbohydr. Polym. 2013, 91, 603–608. [Google Scholar] [CrossRef] [PubMed]
  113. Manandar, M.; Scalarone, G.M. Comparative Studies on Alpha 1-3 Glucan in Blastomyces Dermatitidis Yeast Lysate Antigens and the Use of the Lysates for the Detection of Antibodies. In Proceedings of the Pacific Division American Association for the Advancement of Science, San Francisco, CA, USA, 14–19 August 2009; Volume 28. [Google Scholar]
  114. Hogan, L.H.; Klein, B.S. Altered expression of surface α-1,3-glucan in genetically related strains of Blastomyces dermatitidis that differ in virulence. Infect. Immun. 1994, 62, 3543–3546. [Google Scholar] [CrossRef] [Green Version]
  115. Schoffelmeer, E.A.; Klis, F.M.; Sietsma, J.H.; Cornelissen, B.J. The cell wall of Fusarium oxysporum. Fungal Genet. Biol. 1999, 27, 275–282. [Google Scholar] [CrossRef] [Green Version]
  116. Eissenberg, L.G.; Poirier, S.; Goldman, W.E. Phenotypic variation and persistence of Histoplasma capsulatum Yeasts in host cells. Infect. Immun. 1996, 64, 5310–5314. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  117. San-Blas, G.; Carbonell, L.M. Chemical and ultrastructural studies on the cell wall of the yeast like and mycelial forms of Histoplasma farcinimosum. J. Bacteriol. 1974, 119, 602–611. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  118. Kanestuna, F.; Carbonell, L.M. Cell wall glucans of the yeast and mycelial forms of Paracoccidioides brasiliensis. J. Bacteriol. 1970, 101, 675–680. [Google Scholar]
  119. Parra, E.; Barbero, J.J.; Bernabe, M.; Leal, J.A.; Prieto, A.; Gomez-Miranda, B. Structural investigation of two cell-wall polysaccharides of Penicillium expansum strains. Carbohydr. Res. 1994, 257, 239–248. [Google Scholar] [CrossRef]
  120. Wang, T.; Deng, L.; Li, S.; Tan, T. Structural characterization of a water insoluble (1→3)-α-D-glucan isolated from Penicillium chrysogenum. Carbohydr. Polym. 2007, 67, 133–137. [Google Scholar] [CrossRef]
  121. Haung, Q.; Zhang, L.; Cheung, P.C.K.; Tan, X. Evaluation of sulfated α-glucans from Poria cocos mycelia as a potential antitumor agent. Carbohydr. Polym. 2006, 64, 337–344. [Google Scholar] [CrossRef]
  122. Kiho, T.; Yoshida, I.; Nagai, K.; Ukai, S.; Hara, C. (1→3)-α-D-glucan from an alkaline extract of Agrocybe cylindracea, and antitumor activity of its O-(carboxymethyl)ated derivatives. Carbohydr. Res. 1989, 189, 273–279. [Google Scholar] [CrossRef]
  123. Grun, C. Structure and Biosynthesis of Fungal α-glucans; Universiteit Utrecht, Faculteit Scheikunde: Utrecht, The Netherlands, 2003. [Google Scholar]
  124. Bacon, J.S.D.; Jones, D.; Farmer, V.C.; Webley, D.M. The occurrence of (1→3)-α-glucan in Cryptococcus, Schizosaccharomyces and Polyporus species, and its hydrolysis by a Streptomyces culture filtrate lysing cell walls of Cryptococcus. Biochim. Biophys. Acta 1968, 158, 313–315. [Google Scholar] [CrossRef]
  125. Chen, J.; Zhang, L.; Nakamura, Y.; Norisuye, T. Viscosity behavior and chain Conformation of a (1→3)-α-glucan from Ganoderma lucidum. Polym. Bull. 1998, 41, 471–478. [Google Scholar] [CrossRef]
  126. Chen, J.; Zhou, J.; Zhang, L.; Nakamura, Y.; Norisuye, T. Chemical structure of the water-insoluble polysaccharide isolated from the fruit body of Ganoderma lucidium. Polym. J. 1998, 10, 838–842. [Google Scholar] [CrossRef] [Green Version]
  127. Jelsma, J.; Kreger, D.R. Observations on the cell-wall compositions of the bracket fungi Laetiporus sulphureus and Piptoporus betulinus. Arch. Microbiol. 1978, 119, 249–255. [Google Scholar] [CrossRef]
  128. Zhang, P.; Zhang, L.; Cheng, S. Solution properties of an α-(1→3)-d-glucan from Lentinus edodes and its sulfated derivatives. Carbohydr. Res. 2002, 337, 155–160. [Google Scholar] [CrossRef] [PubMed]
  129. Angyal, S.J.; Bender, J.; Ralph, B.J. Structure of polysaccharides from the Polyporus tumulosus cell wall. Biochim. Biophys. Acta 1974, 362, 175–187. [Google Scholar] [CrossRef]
  130. Siehr, D. Studies on the cell wall of Schizophyllum commune. Permethylation and enzymic hydrolysis. Can. J. Biochem. 1976, 54, 130–136. [Google Scholar] [CrossRef]
  131. Monsan, P.; Bozonnet, S.; Albenne, C.; Joucla, G.; Willemot, R.M.; Remaud-Simeon, M. Homopolysaccharides from Lactic acid bacteria. Int. Dairy J. 2001, 11, 675–685. [Google Scholar] [CrossRef]
  132. Torino, M.I.; de Valdez, G.F.; Mozzi, F. Biopolymers from lactic acid bacteria. Novel applications in foods and beverages. Front. Microbiol. 2015, 6, 834. [Google Scholar] [CrossRef] [Green Version]
  133. Bobbit, T.F.; Nordin, J.H.; Roux, M.; Revol, J.F.; Marchessault, R.H. Distribution and conformation of crystalline nigeranin hyphal walls of Aspergillus niger and Aspergillus awamori. J. Bacteriol. 1977, 132, 691–703. [Google Scholar] [CrossRef] [Green Version]
  134. Miyazaki, T.; Naoi, Y. Chemical structure of the water-soluble glucan from the cell wall of Cladosporium herbarum. Studies on fungal polysaccharide. XV. Chem. Pharm. Bull. 1974, 22, 2058–2063. [Google Scholar] [CrossRef] [Green Version]
  135. Misaki, A.; Tsumuraya, Y.; Takaya, S. A New Fungal α-D-Glucan, Elsinan, Elaborated by Elsinoe Leucospila. Agric. Biol. Chem. 1978, 42, 491–493. [Google Scholar] [CrossRef]
  136. Cardemil, L.; Pincheira, G. Characterization of the carbohydrate component of fraction I in the Neurospora crassa cell wall. J. Bacteriol. 1979, 137, 1067–1072. [Google Scholar] [CrossRef] [Green Version]
  137. Bobbitt, T.F.; Nordin, J.H. Hyphal nigeran as a potential phylogenetic marker for Aspergillus and Penicillium species. Mycologia 1978, 70, 1201–1211. [Google Scholar] [CrossRef] [PubMed]
  138. Hirase, S.; Nakai, S.; Akatsu, T.; Kobayashi, A.; Ohara, M.; Matsunaga, K.; Fujii, M.; Kodaira, S.; Fujii, T.; Furusho, T.; et al. Structural studies on the antitumor active polysaccharides from Coriolus versicolor (Basidiomycetes). II. Structural of β-D-glucan moieties of fractionated polysaccharides. Yakugaku Zasshi 1976, 96, 419–424. [Google Scholar] [CrossRef] [Green Version]
  139. James, P.G.; Cherniak, R. 4-Methylmorpholine N-oxide-methyl sulfoxide soluble glucan of Piptoporus betulinus. Carbohydr. Res. 1990, 206, 167–172. [Google Scholar] [CrossRef] [PubMed]
  140. Olafsdottir, E.S.; Ingolfsdottir, K. Polysaccharides from lichens: Structural characteristics and biological activity. Planta Med. 2001, 67, 199–208. [Google Scholar] [CrossRef]
  141. Shibata, S. Polysaccharides of lichens. J. Nat. Sci. Council. SriLanka 1973, 1, 183–188. [Google Scholar]
  142. Stüde, F. Ueber Everniin, Pectin und eine neue glycogene Substanz. Liebigs Ann. Chem. 1864, 131, 241–251. [Google Scholar] [CrossRef] [Green Version]
  143. Han, X.Q.; Chai, X.Y.; Jia, Y.M.; Han, C.X.; Tu, P.F. Structure elucidation and immunological activity of a novel polysaccharide from the fruit bodies of an edible mushroom, Sarcodon aspratus (Berk. ) S. Ito. Int. J. Biol. Macromol. 2010, 47, 420–424. [Google Scholar] [CrossRef]
  144. Wen, L.; Shi, D.; Zhou, T.; Liu, H.; Jiang, Y.; Yang, B. Immunomodulatory mechanism of α-D-(1→6) glucan isolated from banana. RSC Adv. 2019, 9, 6995–7003. [Google Scholar] [CrossRef]
  145. Zhu, Q.; Jiang, Y.; Lin, S.; Wen, L.; Wu, D.; Zhao, M.; Chen, F.; Jia, Y.; Yang, B. Structural identification of (1→6)-α-D-glucan, a key responsible for the health benefits of longan, and evaluation of anticancer activity. Biomacromol. 2013, 14, 1999–2003. [Google Scholar] [CrossRef]
  146. Cui, H.; Liu, Q.; Tao, Y.; Zhang, H.; Zhang, L.; Ding, K. Structure and chain conformation of a (1→6)-α-D-glucan from the root of Puerarian lobata (Willd.) Ohwi and the antioxidant activity of its sulfated derivative. Carbohydr. Polym. 2008, 74, 771–778. [Google Scholar] [CrossRef]
  147. Zhao, G.H.; Kan, J.Q.; Li, Z.X.; Chen, Z.D. Characterization and immuno stimulatory activity of an (1→6)-α-D-glucan from the root of Ipomoea batatas. Int. Immunopharm. 2005, 5, 1436–1445. [Google Scholar] [CrossRef] [PubMed]
  148. Shi, Y.; Zhao, L.; Liua, X.; Hua, F.; Cui, F.; Bi, Y.; Ma, Y.; Feng, S. Structural characterization of a sulfated glucan isolated from the aqueous extract of Hedysarum polybotrys Hand.-Mazz. Carbohydr. Polym. 2012, 87, 160–169. [Google Scholar] [CrossRef]
  149. Li, X.J.; Bao, W.R.; Leung, C.H.; Ma, D.L.; Zhang, G.; Lu, A.P.; Wang, S.C.; Han, Q.B. Chemical structure and immunomodulating activities of an α-glucan purified from Lobelia chinensis Lour. Molecules 2016, 21, 779. [Google Scholar] [CrossRef] [Green Version]
  150. Morelli, L.; Compostella, F.; Panza, L.; Imperio, D. Unusual Promoters and Leaving Groups in Glycosylation Reactions: The Evolution of Carbohydrate Synthesis. Carbohydr. Res. 2022, 519, 108625. [Google Scholar] [CrossRef] [PubMed]
  151. Singh, Y.; Geringer, S.A.; Demchenko, A.V. Synthesis and Glycosidation of Anomeric Halides: Evolution from Early Studies to Modern Methods of the 21st Century. Chem. Rev. 2022, 122, 11701–11758. [Google Scholar] [CrossRef]
  152. Ishiwata, A.; Tanaka, K.; Ao, J.; Ding, F.; Ito, Y. Recent advances in stereoselective 1,2-cis-O-glycosylations. Front. Chem. 2022, 10, 972429. [Google Scholar] [CrossRef]
  153. Takahashi, D.; Toshima, K. 1,2-cis O-glycosylation methods. In Comprehensive Glycoscience; Barchi, J., Ed.; Elsevier Science: Amsterdam, The Netherlands, 2021; Volume 2, pp. 365–412. [Google Scholar]
  154. Lv, Z.; Liu, H.; Hao, H.; Rahman, F.-U.; Zhang, Y. Chemical synthesis of oligosaccharides and their application in new drug research. Eur. J. Med. Chem. 2023, 249, 115164. [Google Scholar] [CrossRef]
  155. Shadrick, M.; Singh, Y.; Demchenko, A.V. Stereocontrolled α-galactosylation under Cooperative Catalysis. J. Org. Chem. 2020, 85, 15936–15944. [Google Scholar] [CrossRef]
  156. Ishiwata, A.; Lee, Y.J.; Ito, Y. Recent advances in stereoselective glycosylation through intramolecular aglycon delivery. Org. Biomol. Chem. 2010, 8, 3596–3608. [Google Scholar] [CrossRef]
  157. Ishiwata, A.; Ito, Y. Intramolecular Aglycon Delivery. In Selective Glycosylations—Synthetic Methods and Catalysts; Bennett, C.S., Ed.; Wiley: Weinheim, Germany, 2017; Chapter II-4; pp. 81–96. [Google Scholar]
  158. Ishiwata, A. Synthetic Study on Glycoconjugates Containing 1,2-cis Glycoside and Their Application. Trends Glycosci. Glycotech. 2019, 31, SE53–SE54. [Google Scholar] [CrossRef]
  159. Nigudkar, S.S.; Demchenko, A.V. Stereocontrolled 1,2-cis glycosylation as the driving force of progress in synthetic carbohydrate chemistry. Chem. Sci. 2015, 6, 2687–2704. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  160. Leng, W.-L.; Yao, H.; He, J.-X.; Liu, X.-W. Venturing beyond Donor-Controlled Glycosylation: New Perspectives toward Anomeric Selectivity. Acc. Chem. Res. 2018, 51, 628–639. [Google Scholar] [CrossRef] [PubMed]
  161. van der Vorm, S.; Hansen, T.; van Hengst, J.M.A.; Overkleeft, H.S.; van der Marel, G.A.; Codée, J.D.C. Acceptor reactivity in glycosylation reactions. Chem. Soc. Rev. 2019, 48, 4688–4706. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  162. Njeri, D.K.; Valenzuela, E.A.; Ragains, J.R. Leveraging Trifluoromethylated Benzyl Groups toward the Highly 1,2-cis-Selective Glucosylation of Reactive Alcohols. Org. Lett. 2021, 23, 8214–8218. [Google Scholar] [CrossRef] [PubMed]
  163. Kobayashi, Y.; Takemoto, Y. Regio- and stereoselective glycosylation of 1,2-O-unprotected sugars using organoboron catalysts. Tetrahedron 2020, 76, 131328. [Google Scholar] [CrossRef]
  164. Feng, Y.; Guo, T.; Yang, H.; Liu, G.; Zhang, Q.; Zhang, S.; Chai, Y. Ni(II)-Catalyzed Regio- and Stereoselective O-Alkylation for the Construction of 1,2-cis-Glycosidic Linkages. Org. Lett. 2022, 24, 6282–6287. [Google Scholar] [CrossRef]
  165. Ma, Z.; Hu, Y.; Li, X.; Liu, R.; Xia, E.; Xu, P.; Yang, Y. Stereoselective synthesis of α-glucosides with glucosyl (Z)-Ynenoates as donors. Carbohydr. Res. 2023, 523, 108710. [Google Scholar] [CrossRef]
  166. Szarek, W.A.; Horton, D. Anomeric Effect; American Chemical Society: Washington, DC, USA, 1979. [Google Scholar]
  167. Deslongchamps, P. Stereoelectronic Effect in Organic Chemistry; Pergamon: Oxford, UK, 1983. [Google Scholar]
  168. Juaristi, E.; Cuevas, G. The Anomeric Effect; CRC: Boca Raton, FL, USA, 1995. [Google Scholar]
  169. Kirby, A.J. Stereoelectronic Effect; Oxford University Press: New York, NY, USA, 1996. [Google Scholar]
  170. Perrin, C.L. Reverse anomeric effect: Fact or fiction? Tetrahedron 1995, 51, 11901–11935. [Google Scholar] [CrossRef]
  171. Randell, K.D.; Johnston, B.D.; Green, D.F.; Pinto, B.M. Is there a generalized reverse anomeric effect? Substituent and solvent effects on the configurational equilibria of neutral and protonated N-Arylglucopyranosylamines and N-Aryl-5-thioglucopyranosylamines. J. Org. Chem. 2000, 65, 220–226. [Google Scholar] [CrossRef]
  172. Vaino, A.R.; Szarek, W.A. An examination of the purported reverse anomeric effect beyond acetylated N-xylosyl-and N-glucosylimidazoles. J. Org. Chem. 2001, 66, 1097–1102. [Google Scholar] [CrossRef] [PubMed]
  173. Perrin, C.L.; Kuperman, J. Anomeric effects versus steric hindrance to ionic solvation in protonated glucosylanilines and cyclohexylanilines. J. Am. Chem. Soc. 2003, 125, 8846–8851. [Google Scholar] [CrossRef]
  174. Reichardt, C. (Ed.) Solvents and Solvent Effects in Organic Chemistry, 3rd ed.; Wiley-VCH: Weinheim, Germany, 2003. [Google Scholar]
  175. Lemieux, R.U.; Pavia, A.A.; Martin, J.C.; Watanabe, K.A. Solvation effects on conformational equilibria. Studies related to the conformational properties of 2-methoxytetrahydropyran and related methyl glycopyranosides. Can. J. Chem. 1969, 47, 4427–4439. [Google Scholar] [CrossRef]
  176. Eby, R.; Schuerch, C. The Use of 1-O-Tosyl-D-glucopyranose Derivatives in α-D-Glucoside Synthesis. Carbohydr. Res. 1974, 34, 79–90. [Google Scholar] [CrossRef]
  177. Schmidt, R.R.; Rücker, E. Stereoselective glycosidations of uronic acids. Tetrahedron Lett. 1980, 21, 421–1424. [Google Scholar] [CrossRef]
  178. Lemieux, R.U.; Ratcliffe, R.M. The azidonitration of tri-O-acetyl-D-galactal. Can. J. Chem. 1979, 57, 1244–1251. [Google Scholar] [CrossRef] [Green Version]
  179. Ishiwata, A.; Ito, Y. High throughput screening of O-glycosylation conditions. Tetrahedron Lett. 2005, 46, 3521–3524. [Google Scholar] [CrossRef]
  180. Ishiwata, A.; Munemura, Y.; Ito, Y. Synergistic solvent effect in 1,2-cis-glycoside formation. Tetrahedron 2008, 64, 92–102. [Google Scholar] [CrossRef]
  181. Chao, C.-S.; Li, C.-W.; Chen, M.-C.; Chang, S.-S.; Mong, K.-K.T. Low-Concentration 1,2-trans β-Selective Glycosylation Strategy and Its Applications in Oligosaccharide Synthesis. Chem. Eur. J. 2009, 15, 10972–10982. [Google Scholar] [CrossRef]
  182. Chao, C.-S.; Lin, C.-Y.; Mulani, S.; Hung, W.-C.; Mong, K.-K.T. Neighboring-group participation by C-2 ether functions in glycosylations directed by nitrile solvents. Chem. Eur. J. 2011, 17, 12193–12202. [Google Scholar] [CrossRef]
  183. Demchenko, A.; Stauch, T.; Boons, G.J. Solvent and other effects on the stereoselectivity of thioglycoside glycosidations. Synlett 1997, 1997, 818–820. [Google Scholar] [CrossRef] [Green Version]
  184. Takatani, M.; Nakano, J.; Arai, M.A.; Ishiwata, A.; Ohta, H.; Ito, Y. Accelerated glycosylation under frozen conditions. Tetrahedron Lett. 2004, 45, 3929–3932. [Google Scholar] [CrossRef]
  185. Ishiwata, A.; Sakurai, A.; Dürr, K.; Ito, Y. Effects of frozen conditions on stereoselectivity and velocity of O-glycosylation reactions. Bioorg. Med. Chem. 2010, 18, 3687–3695. [Google Scholar] [CrossRef]
  186. Csávás, M.; Herczeg, M.; Bajza, I.; Borbás, A. Protecting Group Manipulations in Carbohydrate Synthesis, Comprehensive Glycoscience, 2nd ed.; Barchi, J.J., Jr., Ed.; Elsevier: Amsterdam, The Netherlands, 2021; pp. 464–524. [Google Scholar]
  187. Ghosh, B.; Kulkarni, S.S. Advances in Protecting Groups for Oligosaccharide Synthesis. Chem. Asian J. 2020, 15, 450–462. [Google Scholar] [CrossRef] [PubMed]
  188. Meyer, A.G.; Bissember, A.C.; Hyland, C.J.T.; Williams, C.C.; Szabo, M.; Pearsall, M.A.; Hyland, I.K.; Olivier, W.J. Seven-Membered Rings. In Progress in Heterocyclic Chemistry; Gribble, G.W., Joule, J.A., Eds.; Elsevier: Amsterdam, The Netherlands, 2017; pp. 579–633. [Google Scholar]
  189. Ma, X.; Zheng, Z.; Fu, Y.; Zhu, X.; Liu, P.; Zhang, L. A “Traceless” Directing Group Enables Catalytic SN2 Glycosylation toward 1,2-cis-Glycopyranosides. J. Am. Chem. Soc. 2021, 143, 11908–11913. [Google Scholar] [CrossRef] [PubMed]
  190. Ma, X.; Zhang, Y.; Zhu, X.; Wei, Y.; Zhang, L. Directed SN2 Glycosylation Employing an Amide-Functionalized 1-Naphthoate Platform Featuring a Selectivity-Safeguarding Mechanism. J. Am. Chem. Soc. 2023, 145, 11921–11926. [Google Scholar] [CrossRef]
  191. Ding, F.; Ishiwata, A.; Ito, Y. Bimodal Glycosyl Donors Protected by 2-O-(ortho-Tosylamido)benzyl Group. Org. Lett. 2018, 20, 4384–4388. [Google Scholar] [CrossRef]
  192. Ding, F.; Ishiwata, A.; Ito, Y. Recent advances of the stereoselective bimodal glycosylations for the synthesis of various glucans. Stud. Nat. Prod. Chem. 2022, 74, 1–40. [Google Scholar]
  193. Ding, F.; Ishiwata, A.; Zhou, S.; Zhong, X.; Ito, Y. Unified Strategy toward Stereocontrolled Assembly of Various Glucans Based on Bimodal Glycosyl Donors. J. Org. Chem. 2020, 85, 5536–5558. [Google Scholar] [CrossRef]
  194. Zhou, S.; Zhong, X.; Guo, A.; Xiao, Q.; Ao, J.; Zhu, W.; Cai, H.; Ishiwata, A.; Ito, Y.; Liu, X.-W.; et al. ZnI2-Directed Stereocontrolled α-glucosylation. Org. Lett. 2021, 23, 6841–6845. [Google Scholar] [CrossRef]
  195. Hoang, K.M.; Lees, N.R.; Herzon, S.B. Programmable Synthesis of 2-Deoxyglycosides. J. Am. Chem. Soc. 2019, 141, 8098–8103. [Google Scholar] [CrossRef] [Green Version]
  196. Hoang, K.L.M.; Liu, X.-W. The Intriguing Dual-directing Effect of 2-Cyanobenzyl Ether for a Highly Stereospecific Glycosylation Reaction. Nat. Commun. 2014, 5, 5051. [Google Scholar] [CrossRef] [Green Version]
  197. Kimura, T.; Eto, T.; Takahashi, D.; Toshima, K. Stereocontrolled Photoinduced Glycosylation Using an Aryl Thiourea as an Organo photoacid. Org. Lett. 2016, 18, 3190–3193. [Google Scholar] [CrossRef] [PubMed]
  198. Wei, R.; Liu, H.; Tang, A.H.; Payne, R.J.; Li, X. A Solution to Chemical Pseudaminylation via a Bimodal Glycosyl Donor for Highly Stereocontrolled α- and β-Glycosylation. Org. Lett. 2019, 21, 3584–3588. [Google Scholar] [CrossRef]
  199. Yang, F.; Sun, Y.; Xu, P.; Molinaro, A.; Silipo, A.; Yu, B. Synthesis of Unprecedented α/β-Alternate (1→4)-Glucans via Stereoselective Iterative Glycosylation. Chem. Eur. J. ASAP 2023, 29, e202300659. [Google Scholar] [CrossRef] [PubMed]
  200. Di Bussolo, V.; Caselli, M.; Romano, M.R.; Pineschi, M.; Crotti, P. New Stereoselective β-C-Glycosidation by Uncatalyzed 1,4-Addition of Organolithium Reagents to a Glycal-Derived Vinyl Oxirane. J. Org. Chem. 2004, 69, 7383–7386. [Google Scholar] [CrossRef] [PubMed]
  201. Di Bussolo, V.; Romano, M.R.; Pineschi, M.; Crotti, P. Stereoselective Synthesis of 4-(N-Mesylamino)-2,3-unsaturated-α-O-glycosides via a New Glycal-Derived Vinyl α-N-(Mesyl)-aziridine. Org. Lett. 2005, 7, 1299–1302. [Google Scholar] [CrossRef] [PubMed]
  202. Ding, F.; William, R.; Wang, F.; Ma, J.; Ji, L.; Liu, X.-W. A Short and Highly Efficient Synthesis of L-Ristosamine and L-epi-Daunosamine Glycosides. Org. Lett. 2011, 13, 652–655. [Google Scholar] [CrossRef]
  203. Ding, F.; William, R.; Wang, S.; Gorityala, B.K.; Liu, X.-W. Ready access to 3-amino-2,3-dideoxysugars via regio- and stereo-selective tandem hydroamination–glycosylation of glycals. Org. Biomol. Chem. 2011, 9, 3929–3939. [Google Scholar] [CrossRef]
  204. Ding, F.; William, R.; Cai, S.T.; Ma, J.; Liu, X.-W. Stereoselective Synthesis of 1,3-cis-3-Arylsulphonaminodeoxydisaccharides and Oligosaccharides. J. Org. Chem. 2012, 77, 5245–5254. [Google Scholar] [CrossRef]
  205. Smolinsky, G. The Vapor Phase Pyrolysis of Several Subsituted Azidobenzenes. J. Org. Chem. 1961, 26, 4108–4110. [Google Scholar] [CrossRef]
  206. Majumdar, K.C.; Ganai, S. An expedient approach to substituted triazolo [1,5-a][1,4]benzodiazepines via Cu-catalyzed tandem Ullmann C–N coupling/azide-alkyne cycloaddition. Tetrahedron Lett. 2013, 54, 6192–6195. [Google Scholar] [CrossRef]
  207. Kowalska, K.; Pedersen, C.M. Catalytic stereospecific O-glycosylation. Chem. Commun. 2017, 53, 2040–2043. [Google Scholar] [CrossRef] [PubMed]
  208. Ding, F.; William, R.; Wang, F.; Liu, X.-W. Triflimide-catalyzed allyl–allyl cross-coupling: A metal-free allylic alkylation. Chem. Commun. 2012, 48, 8709–8711. [Google Scholar] [CrossRef] [PubMed]
  209. Mundal, D.A.; Avetta Jr, C.T.; Thomson, R.J. Triflimide-catalysed sigmatropic rearrangement of N-allylhydrazones as an example of a traceless bond construction. Nat. Chem. 2010, 2, 294–297. [Google Scholar] [CrossRef]
  210. Boxer, M.B.; Yamamoto, H. Triflimide (HNTf2)-catalyzed aldehyde cross-aldol reaction using “super silyl” enol ethers. Nat. Protoc. 2006, 1, 2434–2438. [Google Scholar] [CrossRef]
  211. Wang, P.; Zhu, J.; Yuan, Y.; Danishefsky, S.J. Total Synthesis of the 2,6-Sialylated Immunoglobulin G Glycopeptide Fragment in Homogeneous Form. J. Am. Chem. Soc. 2009, 131, 16669–16671. [Google Scholar] [CrossRef] [Green Version]
  212. Mootoo, D.R.; Konradsson, P.; Udodong, U.; Fraser-Reid, B. Armed and disarmed n-pentenyl glycosides in saccharide couplings leading to oligosaccharides. J. Am. Chem. Soc. 1988, 110, 5583–5584. [Google Scholar] [CrossRef]
  213. Deng, S.; Gangadharmath, U.; Chang, C.-W.T. Sonochemistry:  A Powerful Way of Enhancing the Efficiency of Carbohydrate Synthesis. J. Org. Chem. 2006, 71, 5179–5185. [Google Scholar] [CrossRef] [PubMed]
  214. Ding, F.; Ishiwata, A.; Ito, Y. Stereodivergent Mannosylation Using 2-O-(ortho-Tosylamido)benzyl Group. Org. Lett. 2018, 20, 4833–4837. [Google Scholar] [CrossRef]
  215. Ishiwata, A.; Ito, Y. Glycoscience, Chemistry and Chemical Biology, 2nd ed.; Fraser-Reid, B.O., Tatsuta, K., Thiem, J., Eds.; Springer: Berlin, Germany, 2008; Volume II, Chapter 5.6; pp. 1279–1312. [Google Scholar]
  216. Crich, D.; Sun, S. Formation of β-Mannopyranosides of Primary Alcohols Using the Sulfoxide Method. J. Org. Chem. 1996, 61, 4506–4507. [Google Scholar] [CrossRef]
  217. Crich, D.; Sun, S. Direct Formation of β-Mannopyranosides and Other Hindered Glycosides from Thioglycosides. J. Am. Chem. Soc. 1998, 120, 435–436. [Google Scholar] [CrossRef]
  218. Crich, D.; Sun, S. Direct chemical synthesis of β-mannopyranosides and other glycosides via glycosyl triflates. Tetrahedron 1998, 54, 8321–8348. [Google Scholar] [CrossRef]
  219. Weingart, R.; Schmidt, R.R. Can preferential β-mannopyranoside formation with 4,6-O-benzylidene protected mannopyranosyl sulfoxides be reached with trichloroacetimidates? Tetrahedron Lett. 2000, 41, 8753–8758. [Google Scholar] [CrossRef]
  220. Crich, D.; Smith, M. 1-Benzenesulfinyl Piperidine/Trifluoromethanesulfonic Anhydride:  A Potent Combination of Shelf-Stable Reagents for the Low-Temperature Conversion of Thioglycosides to Glycosyl Triflates and for the Formation of Diverse Glycosidic Linkages. J. Am. Chem. Soc. 2001, 123, 9015–9020. [Google Scholar] [CrossRef] [PubMed]
  221. Crich, D.; Smith, M. Solid-Phase Synthesis of β-Mannosides. J. Am. Chem. Soc. 2002, 124, 8867–8869. [Google Scholar] [CrossRef]
  222. Baek, J.Y.; Choi, T.J.; Jeon, H.B.; Kim, K.S. A Highly Reactive and Stereoselective β-Mannopyranosylation System: Mannosyl 4-Pentenoate/PhSeOTf. Angew. Chem., Int. Ed. 2006, 45, 7436–7440. [Google Scholar] [CrossRef]
  223. Cumpstey, I. Intramolecular Aglycon Delivery. Carbohydr. Res. 2008, 343, 1553–1573. [Google Scholar] [CrossRef]
  224. Fairbanks, A.J. Glycosylation through intramolecular aglycon delivery. In Comprehensive Glycoscience, 2nd ed.; Barchi, J.J., Jr., Ed.; Elsevier Science: Amsterdam, The Netherlands, 2021; Volume 2, pp. 413–434. [Google Scholar]
  225. Barresi, F.; Hindsgaul, O. Synthesis of β-mannopyranosides by intramolecular aglycon delivery. J. Am. Chem. Soc. 1991, 113, 9376–9377. [Google Scholar] [CrossRef]
  226. Stork, G.; Kim, G. Stereocontrolled synthesis of disaccharides via the temporary silicon connection. J. Am. Chem. Soc. 1992, 114, 1087–1088. [Google Scholar] [CrossRef]
  227. Ito, Y.; Ogawa, T. A Novel-Approach to the Stereoselective Synthesis of β-Mannosides. Angew. Chem. Int. Ed. 1994, 33, 1765–1767. [Google Scholar] [CrossRef]
  228. Ennis, S.C.; Fairbanks, A.J.; Tennant-Eyles, R.J.; Yeates, H.S. Steroselective Synthesis of α-Glucosides and β-Mannosides: Tethering and Activation with N-Iodosuccinimide. Synlett 1999, 1999, 1387–1390. [Google Scholar] [CrossRef]
  229. Sati, G.C.; Martin, J.L.; Xu, Y.; Malakar, T.; Zimmerman, P.M.; Montgomery, J. Fluoride Migration Catalysis Enables Simple, Stereoselective, and Iterative Glycosylation. J. Am. Chem. Soc. 2020, 142, 7235–7242. [Google Scholar] [CrossRef] [PubMed]
  230. Pistorio, S.G.; Yasomanee, J.P.; Demchenko, A.V. Hydrogen-Bond-Mediated Aglycone Delivery: Focus on β-mannosylation. Org. Lett. 2014, 16, 716–719. [Google Scholar] [CrossRef]
  231. David, S.; Malleron, A.; Dini, C. Preparation of oligosaccharides with β-D-mannopyranosyl and 2-azido-2-deoxy-β-D-mannopyranosyl residues by inversion at C-2 after coupling. Carbohydr. Res. 1989, 188, 193–200. [Google Scholar] [CrossRef]
  232. Matsuo, I.; Isomura, M.; Ajisaka, K. Synthesis of an asparagine-linked core pentasaccharide by means of simultaneous inversion reactions. J. Carbohydr. Chem. 1999, 18, 841–850. [Google Scholar] [CrossRef]
  233. Twaddle, G.W.J.; Yashunsky, D.V.; Nikolaev, A.V. The chemical synthesis of β-(1→4)-linked D-mannobiose and D-mannotriose. Org. Biomol. Chem. 2003, 1, 623–628. [Google Scholar] [CrossRef]
  234. Sato, K.; Akai, S.; Yoshitomo, A.; Takai, Y. An improved method for synthesizing antennary β-d-mannopyranosyl disaccharide units. Tetrahedron Lett. 2004, 45, 8199–8201. [Google Scholar] [CrossRef]
  235. Ishii, N.; Ogiwara, K.; Sano, K.; Kumada, J.; Yamamoto, K.; Matsuzaki, Y.; Matsuo, I. Specificity of Donor Structures for endo-β-N-Acetylglucosaminidase-Catalyzed Transglycosylation Reactions. ChemBioChem 2018, 19, 136–141. [Google Scholar] [CrossRef]
  236. Meng, S.; Bhetuwal, B.R.; Nguyen, H.; Qi, X.; Fang, C.; Saybolt, K.; Li, X.; Liu, P.; Zhu, J. β-mannosylation through O-Alkylation of Anomeric Cesium Alkoxides: Mechanistic Studies and Synthesis of the Hexasaccharide Core of Complex Fucosylated N-Linked Glycans. Eur. J. Org. Chem. 2020, 2020, 2291–2301. [Google Scholar] [CrossRef]
  237. O’Sullivan, S.; Doni, E.; Tuttle, T.; Murphy, J.A. Metal-free reductive cleavage of C–N and S–N bonds by photoactivated electron transfer from a neutral organic donor. Angew. Chem. Int. Ed. 2014, 53, 474–478. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  238. Niggemann, M.; Fu, L.; Damsen, H. Taming a vinyl cation with a simple Al(OTf)3 catalyst to promote C−C bond cleavage. Chem. Eur. J. 2017, 23, 12184–12189. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  239. Nakajima, T.; Sasaki, H.; Sato, M.; Tamari, K.; Matsuda, K. A Cell Wall Proteo-Heteroglycan from Piricularia oryzae: Further Studies of the Structure. J. Biochem. 1977, 82, 1657–1662. [Google Scholar] [CrossRef] [PubMed]
  240. Vijay, I.K.; Perdew, G.H. Biosynthesis of mammary glycoproteins structural characterization of lipid-linked glucosyloligosaccharides. Eur. J. Biochem. 1982, 126, 167–172. [Google Scholar] [CrossRef]
  241. Gunnarsson, A.; Svensson, S. Structural studies on the O-glycosidically linked carbohydrate chains of glucoamylase G1 from Aspergillus niger. Eur. J. Biochem. 1984, 145, 463–467. [Google Scholar] [CrossRef]
  242. Trinel, P.A.; Maes, E.; Zanetta, J.P.; Delplace, F.; Coddeville, B.; Jouault, T.; Strecker, G.; Poulain, D. Candida albicans phospholipomannan, a new member of the fungal mannose inositol phosphoceramide family. J. Biol. Chem. 2002, 277, 37260. [Google Scholar] [CrossRef] [Green Version]
  243. Goto, M. Protein O-glycosylation in fungi: Diverse structures and multiple functions. Biosci. Biotechnol. Biochem. 2007, 71, 1415–1427. [Google Scholar] [CrossRef] [Green Version]
  244. Aubry, S.; Sasaki, K.; Sharma, I.; Crich, D. Influence of Protecting Groups on the Reactivity and Selectivity of Glycosylation: Chemistry of the 4,6-O-Benzylidene Protected Mannopyranosyl Donors and Related Species. Top. Curr. Chem. 2010, 301, 141–188. [Google Scholar]
  245. Crich, D. Mechanism of a Chemical Glycosylation. Acc. Chem. Res. 2010, 43, 1144–1153. [Google Scholar] [CrossRef]
  246. Zhong, X.; Zhou, S.; Ao, J.; Guo, A.; Xiao, Q.; Huang, Y.; Zhu, W.; Cai, H.; Ishiwata, A.; Ito, Y.; et al. Zinc(II) Iodide-Directed β-mannosylation: Reaction Selectivity, Mode, and Application. J. Org. Chem. 2021, 86, 16901–16915. [Google Scholar] [CrossRef]
  247. Zhou, S.; Ao, J.; Guo, A.; Zhao, X.; Deng, N.; Wang, G.; Yang, Q.; Ishiwata, A.; Liu, X.-W.; Li, Q.; et al. ZnI2-mediated β-galactosylation of C2-Ether-Type Donor. Org. Lett. 2022, 24, 8025–8030. [Google Scholar] [CrossRef] [PubMed]
  248. Pongener, I.; Pepe, D.A.; Ruddy, J.J.; McGarrigle, E.M. Stereoselective β-mannosylations and β-rhamnosylations from glycosyl hemiacetals mediated by lithium iodide. Chem. Sci. 2021, 12, 10070–10075. [Google Scholar] [CrossRef] [PubMed]
  249. Feng, Y.; Yang, J.; Cai, C.; Sun, T.; Zhang, Q.; Chai, Y. Catalytic and highly stereoselective β-mannopyranosylation using a 2,6-lactone-bridged mannopyranosyl ortho-hexynylbenzoate as donor. Chin. Chem. Lett. 2022, 33, 4878–4881. [Google Scholar] [CrossRef]
  250. Gucchait, A.; Ghosh, A.; Kumar Misra, A. Convergent synthesis of the pentasaccharide repeating unit of the biofilms produced by Klebsiella pneumoniae. Beilstein J. Org. Chem. 2019, 15, 431–436. [Google Scholar] [CrossRef] [PubMed]
  251. Zeng, C.; Sun, B.; Cao, X.; Zhu, H.; Oluwadahunsi, O.M.; Liu, D.; Zhu, H.; Zhang, J.; Zhang, Q.; Zhang, G.; et al. Chemical Synthesis of Homogeneous Human E-Cadherin N-Linked Glycopeptides: Stereoselective Convergent Glycosylation and Chemoselective Solid-Phase Aspartylation. Org. Lett. 2020, 22, 8349–8353. [Google Scholar] [CrossRef]
  252. Helenius, A.; Aebi, M. Intracellular Functions of N-Linked Glycans. Science 2001, 291, 2364–2369. [Google Scholar] [CrossRef] [Green Version]
  253. Wang, Z.; Chinoy, Z.S.; Ambre, S.G.; Peng, W.; McBride, R.; de Vries, R.P.; Glushka, J.; Paulson, J.C.; Boons, G.-J. A General Strategy for the Chemoenzymatic Synthesis of Asymmetrically Branched N-Glycans. Science 2013, 341, 379–383. [Google Scholar] [CrossRef] [Green Version]
  254. Koizumi, A.; Matsuo, I.; Takatani, M.; Seko, A.; Hachisu, M.; Takeda, Y.; Ito, Y. Top-Down Chemoenzymatic Approach to a High-Mannose-Type Glycan Library: Synthesis of a Common Precursor and Its Enzymatic Trimming. Angew. Chem. Int. Ed. 2013, 52, 7426–7431. [Google Scholar] [CrossRef]
  255. Shivatare, S.S.; Chang, S.-H.; Tsai, T.-I.; Ren, C.-T.; Chuang, H.-Y.; Hsu, L.; Lin, C.-W.; Li, S.-T.; Wu, C.-Y.; Wong, C.-H. Efficient Convergent Synthesis of Bi-, Tri-, and Tetra-Antennary Complex Type N-Glycans and Their HIV-1 Antigenicity. J. Am. Chem. Soc. 2013, 135, 15382–15391. [Google Scholar] [CrossRef]
  256. Walczak, M.A.; Hayashida, J.; Danishefsky, S.J. Building Biologics by Chemical Synthesis: Practical Preparation of Di- and Triantennary N-Linked Glycoconjugates. J. Am. Chem. Soc. 2013, 135, 4700–4703. [Google Scholar] [CrossRef] [Green Version]
  257. Chao, Q.; Ding, Y.; Chen, Z.-H.; Xiang, M.-H.; Wang, N.; Gao, X.-D. Recent Progress in Chemo-Enzymatic Methods for the Synthesis of N-Glycans. Front. Chem. 2020, 8, 513. [Google Scholar] [CrossRef]
  258. Kashiwagi, G.A. Intrinsic Issues in the Assembly of 1,2-Linked Oligosaccharides. Asian J. Org. Chem. 2020, 9, 689–697. [Google Scholar] [CrossRef]
  259. Ikuta, D.; Hirata, Y.; Wakamori, S.; Shimada, H.; Tomabechi, Y.; Kawasaki, Y.; Ikeuchi, K.; Hagimori, T.; Matsumoto, S.; Yamada, H. Conformationally supple glucose monomers enable synthesis of the smallest cyclodextrins. Science 2019, 364, 674–677. [Google Scholar] [CrossRef] [PubMed]
  260. Zhu, Y.; Delbianco, M.; Seeberger, P.H. Automated Assembly of Starch and Glycogen Polysaccharides. J. Am. Chem. Soc. 2021, 143, 9758–9768. [Google Scholar] [CrossRef] [PubMed]
Figure 1. The linkages of α-D-glucans. (a) The linkages in the linear α-D-glucans; (b) the linkages of the branching in the various α-D-glucans.
Figure 1. The linkages of α-D-glucans. (a) The linkages in the linear α-D-glucans; (b) the linkages of the branching in the various α-D-glucans.
Molecules 28 05644 g001
Figure 2. 2-O-ether-protected glycosyl donors. (a) The 2-O-ether-protected glycosyl donors for stereoselective glycosylation; (b) TAB-protected donors for bimodal glycosylations.
Figure 2. 2-O-ether-protected glycosyl donors. (a) The 2-O-ether-protected glycosyl donors for stereoselective glycosylation; (b) TAB-protected donors for bimodal glycosylations.
Molecules 28 05644 g002
Scheme 1. Bimodal glycosylation of TAB-protected glucosyl donor 1f. (a) Synthesis of TAB-protected donor 1f; (b) bimodal glycosylation condition using single TAB-protected donor 1f by changing the reaction conditions; (c) proposed pathway of stereoselection for both 1,2-cis and 1,2-trans glucosylation.
Scheme 1. Bimodal glycosylation of TAB-protected glucosyl donor 1f. (a) Synthesis of TAB-protected donor 1f; (b) bimodal glycosylation condition using single TAB-protected donor 1f by changing the reaction conditions; (c) proposed pathway of stereoselection for both 1,2-cis and 1,2-trans glucosylation.
Molecules 28 05644 sch001
Scheme 2. Bimodal glycosylation of TAB-protected galactosyl and mannosyl donors (1fGal and 1fMan). (a) Bimodal galactosylation conditions; (b) bimodal mannosylation conditions; (c) proposed pathway of stereocontrol for mannosylation of 1fMan.
Scheme 2. Bimodal glycosylation of TAB-protected galactosyl and mannosyl donors (1fGal and 1fMan). (a) Bimodal galactosylation conditions; (b) bimodal mannosylation conditions; (c) proposed pathway of stereocontrol for mannosylation of 1fMan.
Molecules 28 05644 sch002
Figure 3. Donors for ZnI2-mediated 1,2-cis glycosylations.
Figure 3. Donors for ZnI2-mediated 1,2-cis glycosylations.
Molecules 28 05644 g003
Scheme 3. ZnI2-mediated 1,2-cis glycosylations. (a-1) Stereoselective 1,2-cis α-glucosylation and (a-2) TS structure for 1,2-cis α-glucosylation; (b-1) stereoselective 1,2-cis β-mannosylation and (b-2) TS structure for 1,2-cis α-glucosylation; (c-1) stereoselective cis β-galactosylation and (c-2) TS structure for 1,2-cis α-glucosylation. TS structures were proposed by DFT calculations. For Ar, P, and R, CH3-, CH3-, and CH3CH2- were used for the calculation instead of Nap, Bn, and an acceptor molecule, respectively.
Scheme 3. ZnI2-mediated 1,2-cis glycosylations. (a-1) Stereoselective 1,2-cis α-glucosylation and (a-2) TS structure for 1,2-cis α-glucosylation; (b-1) stereoselective 1,2-cis β-mannosylation and (b-2) TS structure for 1,2-cis α-glucosylation; (c-1) stereoselective cis β-galactosylation and (c-2) TS structure for 1,2-cis α-glucosylation. TS structures were proposed by DFT calculations. For Ar, P, and R, CH3-, CH3-, and CH3CH2- were used for the calculation instead of Nap, Bn, and an acceptor molecule, respectively.
Molecules 28 05644 sch003
Scheme 4. Synthesis of possible D-Glc-(1→2)-D-Glc-(1→6)-α-D-Glc-OMe derivatives using bimodal glycosylation methodology using TAB-protected donor. (a) Synthesis of α-D-Glc-(1→2)-α-D-Glc-(1→6)-α-D-Glc-OMe and β-D-Glc-(1→2)-α-D-Glc-(1→6)-α-D-Glc-OMe from α-5f; (b) synthesis of α-D-Glc-(1→2)-β-D-Glc-(1→6)-α-D-Glc-OMe and β-D-Glc-(1→2)-β-D-Glc-(1→6)-α-D-Glc-OMe from β-5f.
Scheme 4. Synthesis of possible D-Glc-(1→2)-D-Glc-(1→6)-α-D-Glc-OMe derivatives using bimodal glycosylation methodology using TAB-protected donor. (a) Synthesis of α-D-Glc-(1→2)-α-D-Glc-(1→6)-α-D-Glc-OMe and β-D-Glc-(1→2)-α-D-Glc-(1→6)-α-D-Glc-OMe from α-5f; (b) synthesis of α-D-Glc-(1→2)-β-D-Glc-(1→6)-α-D-Glc-OMe and β-D-Glc-(1→2)-β-D-Glc-(1→6)-α-D-Glc-OMe from β-5f.
Molecules 28 05644 sch004
Scheme 5. Synthesis of linear and branched α-glucan fragments using TAB-protected glucosyl donors. (a) Synthesis of linear (1→6)-α-D-glucan fragments and α-(1→3)-branched (1→6)-α-D-glucan fragment; (b) synthesis of linear (1→3)-α-D-glucan fragments; (c) synthesis of linear (1→4)-α-D-glucan fragments; (d) synthesis of linear (1→4)-α-D-glucan pentasaccharide; (e) synthesis of α-(1→6)-branched (1→4)-α-D-glucan hexasaccharide.
Scheme 5. Synthesis of linear and branched α-glucan fragments using TAB-protected glucosyl donors. (a) Synthesis of linear (1→6)-α-D-glucan fragments and α-(1→3)-branched (1→6)-α-D-glucan fragment; (b) synthesis of linear (1→3)-α-D-glucan fragments; (c) synthesis of linear (1→4)-α-D-glucan fragments; (d) synthesis of linear (1→4)-α-D-glucan pentasaccharide; (e) synthesis of α-(1→6)-branched (1→4)-α-D-glucan hexasaccharide.
Molecules 28 05644 sch005
Scheme 6. Synthesis of linear and branched α-glucan fragments using ZnI2-mediated 1,2-cis glycosylations. (a,b) Synthesis of linear (1→3)-α-glucan fragments, nigerotetraoside, and nigerooctaoside derivatives; (c) synthesis of α-(1→6)-branched (1→4)-α-glucantetrasaccharide; (d) synthesis of α-(1→3)-branched (1→6)-α-glucantetrasaccharide.
Scheme 6. Synthesis of linear and branched α-glucan fragments using ZnI2-mediated 1,2-cis glycosylations. (a,b) Synthesis of linear (1→3)-α-glucan fragments, nigerotetraoside, and nigerooctaoside derivatives; (c) synthesis of α-(1→6)-branched (1→4)-α-glucantetrasaccharide; (d) synthesis of α-(1→3)-branched (1→6)-α-glucantetrasaccharide.
Molecules 28 05644 sch006
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content.

Share and Cite

MDPI and ACS Style

Ishiwata, A.; Tanaka, K.; Ito, Y.; Cai, H.; Ding, F. Recent Progress in 1,2-cis glycosylation for Glucan Synthesis. Molecules 2023, 28, 5644. https://doi.org/10.3390/molecules28155644

AMA Style

Ishiwata A, Tanaka K, Ito Y, Cai H, Ding F. Recent Progress in 1,2-cis glycosylation for Glucan Synthesis. Molecules. 2023; 28(15):5644. https://doi.org/10.3390/molecules28155644

Chicago/Turabian Style

Ishiwata, Akihiro, Katsunori Tanaka, Yukishige Ito, Hui Cai, and Feiqing Ding. 2023. "Recent Progress in 1,2-cis glycosylation for Glucan Synthesis" Molecules 28, no. 15: 5644. https://doi.org/10.3390/molecules28155644

Article Metrics

Back to TopTop