Search Results (65)

Enhancing the oxidation resistance of copper nanoparticles (CuNPs) is a crucial objective in plasmonic photocatalytic reactions. In this study, a series of Cu/X catalysts was synthesized using semiconductor nanomaterials (X = TiO₂, ZnO, BN, TiN, SiC, and C₃N₄) as supports for CuNPs. These catalysts were systematically evaluated in visible-light-driven photocatalytic oxidative homocoupling of phenylacetylene (OHA). Comprehensive characterization revealed distinct metal-support interactions and nanostructure evolution during repeated catalytic cycles. The photocatalytic performance, copper leaching, and structural stability of the catalysts were compared. Cu/TiO₂ achieved the highest 1,3-diyne yield (up to 93%) in the first two cycles. In contrast, Cu/ZnO showed minimal copper leaching and excellent recyclability, retaining high activity over three consecutive cycles without the need for reduction pretreatment. Comparative studies revealed that the combination of localized surface plasmon resonance (LSPR) and efficient electron transfer within the Cu⁰-Cu₂O-CuO composite was a key factor in enhancing the photocatalytic activity and stability. These findings provide new insights into the rational design of durable CuNP-based photocatalysts for visible-light-driven organic transformations. Full article

Cytisine, a naturally occurring alkaloid and partial agonist of nicotinic acetylcholine receptors (nAChRs), has long been used as a smoking cessation aid and serves as the pharmacophore for varenicline. Recent research has expanded its therapeutic scope to neurodegenerative and neurological disorders, motivating the development of new cytisine derivatives. Among these, N-propargylcytisine combines the biological activity of the parent compound with the synthetic versatility of the terminal alkyne group. Herein, we report the synthesis and characterization of N-propargylcytisine, and its symmetrical dimer linked through 1,3-diyne moiety obtained via a copper-mediated Glaser–Hay oxidative coupling. The products were analyzed by NMR, FT-IR, and mass spectrometry, confirming the introduction of the propargyl moiety and the formation of the diyne bridge. Solvatochromic study of both compounds were performed using UV-VIS absorption spectroscopy in solvents of varying polarity, including protic solvents capable of hydrogen bonding. The 1,3-diyne motif, commonly found in bioactive natural products, endows the resulting dimer with potential for further derivatization and biological evaluation. This study demonstrates the utility of the Glaser–Hay reaction in the functionalization of alkaloid scaffolds and highlights the prospects of N-propargylcytisine derivatives in drug discovery targeting the central nervous system. Full article

The cationic chloro-P-{[4-(diphenylphosphanyl)phenyl]-N,N-dimethylmethanammonio(norbornadiene)rhodium(I) complex was encapsulated inside a self-assembled hexameric capsule. This capsule was obtained through a reaction involving 2,8,14,20-tetra-undecyl-resorcin[4]arene and water in chloroform. The formation of an inclusion complex was deduced from a combination of spectral measurements (UV-visible spectroscopy, ¹H, ³¹P{¹H} NMR and DOSY). The rhodium complex was evaluated in the [2+2+2] cycloaddition between N,N-dipropargyl-p-toluenesulfonamide and arylacetylene derivatives. In the presence of two equivalents of arylacetylenes in water-saturated chloroform at 60 °C for 24 h, the 4-methyl-N-(prop-2-yn-1-yl)-N-((2-tosylisoindolin-5-yl)methyl)benzenesulfonamide, the homocycloaddition product of 1,6-diyne is predominantly formed. In the presence of the supramolecular capsule, a selectivity inversion in favor of 5-aryl-2-tosylisoindoline is observed, with heterocycloaddition products formed in proportions between 53 and 69%. Full article

Objectives. The relationships among neuropathic pain, gut microbiota, microbiome-derived metabolites, and neuropathology have received increasing attention. This study examined the effects of two dosages of gingerol-enriched ginger (GEG) on mechanical hypersensitivity, anxiety-like behavior, gut microbiome composition and its metabolites, and neuropathology markers in female rats in the spinal nerve ligation (SNL) model of neuropathic pain. Methods. Forty female rats were assigned to 4 groups: sham-vehicle, SNL-vehicle, SNL+GEG at 200 mg/kg BW, and SNL+GEG at 600 mg/kg BW via oral gavage. All animals were given an AIN-93G diet for 5 weeks. Mechanical hypersensitivity was assessed by the von Frey test. Anxiety-like behavior was assessed by the open field test. Fecal microbiota composition and metabolites were determined using 16S rRNA gene sequencing and GC-MS, respectively. Neuropathology gene expression profiling of the amygdala was assessed by an nCounter^® Neuropathology pathway panel. Results. Both GEG-treated groups showed decreased mechanical hypersensitivity and anxiety-like behavior in the SNL model. Gut microbiome diversity in both GEG groups was decreased compared with untreated SNL rats. In the SNL model, phyla such as Bacteroidota, Proteobacteria and Verrucomicrobiota were decreased. Compared with the untreated SNL group, both GEG groups exhibited increased abundance of the phyla Bacteroidota (i.e., Rikenella, Alistipes, Muribaculaceae, Odoribacter), Firmicutes (i.e., UBA1819, Ruminococcaceae, Oscillospiraceae, Roseburia), and Verrucomicrobiota (i.e., Victivallis). GEG groups had higher levels of nine hydrophilic positive metabolites [val-glu, urocanic acid, oxazolidinone, L-threonine, L-norleucine, indole, imino-tryptophan, 2,3-octadiene-5,7-diyn-1-ol, and (2E)-3-(3-hydroxyphenyl) acrylaldehyde] and two hydrophilic negative metabolites [methylmalonic acid and metaphosphoric acid], as well as lower levels of five hydrophilic metabolites [xanthine, N-acetylmuramic acid, doxaprost, adenine, and 1-myristoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine]. Among the 770 neuropathology genes, 1 gene (PLA2G4A) was upregulated and 2 genes (CDK5R1 and SHH) were downregulated in SNL rats. GEG caused the upregulation of nine genes (APC, CCNH, EFNA5, GRN, HEXB, ITPR1, PCSK2, TAF9, and WFS1) and downregulation of three genes (AVP, C4A, and TSPO) in the amygdala. Conclusions. GEG supplementation mitigated pain-associated behaviors in female rats with neuropathic pain, in part by reversing the molecular neuropathology signature of the amygdala. This was associated with changes in the gut microbiome composition and fecal metabolites, which could play a role in mediating the effects of GEG on neuropathic pain. Full article

We report the topochemical solid-state polymerization of different series of symmetrical diacetylenes (DAs) and asymmetrical chlorodiacetylenes (ClDAs), whose members differ in their alkyl spacing lengths of one to four methylene units (n = 1, 2, 3, 4) between the diyne and carbamate functionalities. Structure determination by single-crystal X-Ray diffraction (SCXRD) confirms that in each of these series, at least 50% of the analyses show monomers with a particular stacking pattern presenting two potential directions of polymerization simultaneously. An organization of a crystalline polydiacetylene (PDA) with an oblique chain orientation with respect to the network of cooperatives hydrogen bonds is rather rare in the literature (only two cases), and here we have obtained two more examples of this type of structural motif (supported by SCXRD analysis of the polymer). Orientation control is essential to optimize the performance of conjugated polymers, and a spacer length modification strategy presents a potential way to achieve this in the case of PDA. Full article

One novel C₁₀ polyacetylene rhamnoside, 4,6,8-decatriyne-1-O-α-L-rhamnopyranoside, named xylariside A (1), together with two novel C₁₀ polyacetylene quinovopyranosides, 4,6,8-decatriyne-1-O-α-D-quinovopyranoside, xylariside B (2), and 8E-decaene-4,6-diyne-1-O-α-D-quinovopyranoside, xylariside C (3), were obtained from the solid fermentation of Xylaria sp. VDL4, an endophytic fungus isolated from Vaccinium dunalianum wight (Ericaceae). Their chemical structures were elucidated through a combination of spectroscopic techniques. The antifungal activities of these compounds were evaluated in vitro against four phytopathogenic fungi (Fusarium oxysporum, Botrytis cinerea, Phytophthora capsici, and Fusarium solani). Compound 2 demonstrated significant antifungal activities, with minimum inhibitory concentration (MIC) values ranging from 3.91 to 7.81 μg/mL. Compound 2’s effectiveness levels were similar to those of the reference drugs thiabendazole and carbendazim (each MIC = 0.98−15.62 μg/mL). Xylariside B (2) was further evaluated against B. cinerea in vivo. It exhibited remarkable efficacy in both the prevention and treatment of tomato and strawberry gray mold. Molecular docking studies confirmed the antifungal mechanism of compound 2 by revealing its binding interactions with key enzyme targets in B. cinerea, thereby supporting the observed in vitro and in vivo results. Additionally, compound 2 showed effective inhibition of α-glucosidase, with IC₅₀ values of 5.27 ± 0.0125 μg/mL. Full article

The emergence of RNA viruses driven by global population growth and international trade highlights the urgent need for effective antiviral agents that can inhibit viral replication. Nucleoside analogs, which mimic natural nucleotides, have shown promise in targeting RNA-dependent RNA polymerases (RdRps). Starting from protected 5-iodouridine, we report the synthesis of hitherto unknown C5-substituted-(1,3-diyne)-uridines nucleosides and their phosphoramidate prodrugs. The modifications at C5 include 4-(trifluoromethyl)benzene (a), 4-pentyl-benzene (b), 3,5-dimethoxy-benzene (c), 4-(trifluoromethoxy)benzene (d), 3-aniline (e), 4-pyridine (f), 3-thiophene (g), C₆H₁₃ (h), 2-pyrimidine (i), cyclopropyl (j), and phenyl (k) groups. These compounds were synthesized using Sonogashira palladium-catalyzed reactions and nickel–copper-catalyzed C-H activation between various alkynes, yielding between 25% and 67%. The antiviral activities of obtained compounds were measured through HTS against RNA viruses including influenza H1N1 and H3N2, human respiratory syncytial virus (RSV), SARS-CoV-2, Zika, hepatitis C virus (HCV), Hepatitis E virus (HEV), as well as against coronavirus (HCoV-229E). Unfortunately, none of them showed promising antiviral activity, with less than 85% inhibition observed in the cell viability screening of infected cells. Full article

As an extension of our study of the reactivity of derivatives of 3,3,4,4-tetraethoxybut-1-yne, attempts have been made to achieve acid-catalyzed deacetalization of the diethoxymethyl moieties in 5-diethoxymethyl-1,1,2,2-tetraethoxyundeca-3,6-diyn-5-ol. That was not achieved; instead, only deketalization occurred and afforded the title compound, indicating that the triple bond activates the propargylic diethoxy moiety relative to the other acetal groups. Full article

Background/Objectives: Bacterial resistance and virulence are challenges in treating bacterial infections, especially in Klebsiella pneumoniae. Plants of the Launaea Cass. genus are used traditionally to address a variety of diseases, including infections, but the potential bioactive compounds are unknown. Our goals were to verify the potential contribution of two major polyacetylene glycosides isolated from our previous study, (3S,6E,12E)-6,12-tetradecadiene-8,10-diyne-1-ol 3-O-β-D-glucopyranoside (1) and bidensyneoside A (syn. gymnasterkoreaside A) [(3R,8E)-3-hydroxy-8-decene-4,6-diyn-1-yl β-D-glucopyranoside] (2), to the anti-infective properties of Launaea capitata and to develop a dependable HPLC method for their quantification; Methods: On a panel of K. pneumoniae clinical isolates, the antibacterial action of 1, 2, and the methanol extract of the whole L. capitata plant were evaluated by broth microdilution assay, while their antibiofilm action was evaluated by the crystal violet assay. qRT-PCR investigated luxS, mrkA, wzm, and wbbm genes that encode biofilm formation and quorum sensing (QS). The antibacterial activity of 1 was revealed by employing mice infection. Chromatographic separation was conducted using isocratic elution on a Hypersil BDS C18 column using a photodiode array (PDA) detector; Results: Compound 1 showed antibacterial activity with MIC values of 16–128 µg/mL. It remarkably reduced strong and moderate biofilm-forming bacterial isolates from 84.21% to 42.1% compared with the extract (68.42%) and 2 (78.95%). Compound 1 also downregulated the QS genes, luxS, mrkA, wzm, and wbbm, and exhibited in vivo antibacterial action through the enhancement of the histological construction of the liver and spleen, decreased TNF-α immunoreaction, bacterial burden, and the inflammatory mediators IL-1β and IL-6. A successful HPLC-PDA approach was developed to separate the binary mixture of 1 and 2 in less than 10 min with high sensitivity, with detection limits down to 0.518 and 0.095 µg/mL for 1 and 2, respectively; Conclusions: Compound 1 exhibited remarkable antibacterial and antibiofilm properties and may contribute to the anti-infectious traditional uses of L. capitata, meriting further clinical studies and serving as a reliable quality control biomarker for the plant. Full article

For their great structural versatility, thiophene-based π-conjugated systems have been widely exploited in the preparation of low band gap materials. Here, we report the synthesis of a highly conjugated tetrathiophene system, namely 1,4-di([2,2′-bithiophen]-3-yl)buta-1,3-diyne (1), that presents two bithiophene units connected at position 3 by a butadiynylene spacer. Single-crystal X-ray diffraction (SC-XRD) analysis elucidated the structure of 1, confirming the planarity of the molecule. The molecule was then electropolymerized onto the surface of a gold-coated piezoelectric quartz crystal, showing a high reactivity that is ascribable to the extended conjugation. The frontier molecular orbital energies of 1 were obtained via DFT optimization performed on the crystal structure-derived molecular geometry. Finally, DFT was also used to estimate the polymer band gap. Full article

Clickable nucleosides, most often 5-ethynyl-2′-deoxyuridine (EtU), are widely used in studies of DNA replication in living cells and in DNA functionalization for bionanotechology applications. Although clickable dNTPs are easily incorporated by DNA polymerases into the growing chain, afterwards they might become targets for DNA repair systems or interfere with faithful nucleotide insertion. Little is known about the possibility and mechanisms of these post-synthetic events. Here, we investigated the repair and (mis)coding properties of EtU and two bulkier clickable pyrimidine nucleosides, 5-(octa-1,7-diyn-1-yl)-U (C8-AlkU) and 5-(octa-1,7-diyn-1-yl)-C (C8-AlkC). In vitro, EtU and C8-AlkU, but not C8-AlkC, were excised by SMUG1 and MBD4, two DNA glycosylases from the base excision repair pathway. However, when placed into a plasmid encoding a fluorescent reporter inactivated by repair in human cells, EtU and C8-AlkU persisted for much longer than uracil or its poorly repairable phosphorothioate-flanked derivative. DNA polymerases from four different structural families preferentially bypassed EtU, C8-AlkU and C8-AlkC in an error-free manner, but a certain degree of misincorporation was also observed, especially evident for DNA polymerase β. Overall, clickable pyrimidine nucleotides could undergo repair and be a source of mutations, but the frequency of such events in the cell is unlikely to be considerable. Full article

Sensory attributes strongly influence consumers’ preferences for products. The inoculation of the Klebsiella variicola H8 strain in a reconstituted tobacco leaf concentrate (RTLC) solution increased neutral aroma-enhancing compound (NAEC) production by 45%, decreased the nicotine level by 25%, decreased the water-soluble total sugar content by ~36%, and improved the sensory quality by 5.71%. The production of NAECs such as dihydrokiwi lactone (DHKL: 192.86%), 1,2,3,4-tetrahydro-1,1,6-trimethylnaphthalene (THTMN: 177.77%), 2,4-di-tert-butylphenol (DTBP: 25%), 4-oxoisofolkone (OIFK: 116.66%,) 1,9-heptadecadiene-4,6-diyn-3-ol (HDD: 116.67%), β-damastrone (BDS: 116.67), and megastigmatrienone A (MSTA: 116.67%) was increased. A metagenomics analysis of the microbial community in the fermented RTLC (FRTLC) was performed to elucidate the mechanism by which NAECs were produced. As a result, 24 groups of functional genes were identified, and among them, five families of carbohydrate-active enzymes, (i) glycoside hydrolase (GH), (ii) glycosyltransferase (GT), (iii) polysaccharide lyase (PL), (iv) carbohydrate esterase (CE), and (v) auxiliary active enzyme (AA), were found to be positively correlated with the production of NAECs. However, among the GHs, the GHs annotated from the H8 strain chromosome displayed the highest relative abundance and a positive correlation with the production of NAECs. Specifically, the GH13-14, GH13-20, GH13-38, GH13-25, GH13-10, GH42, and GH28 genes of the H8 strain were relatively more abundant and were key contributors to the production of NAECs. The correlation analyses revealed that the H8 strain plays a leading role among all the microorganisms in FRTLC in the production of NAECs. Our findings support the application of Klebsiella variicola in NAEC production and a reduction in nicotine content in tobacco products. Full article

We present the first example of visible-light-mediated multicomponent annulation of 1,7-diynes by taking advantage of quadruple cleavage olf carbon-halogen bonds of BrCCl₃ to generate a C1 synthon, which was adeptly applied to the preparation of skeletally diverse 3-benzoyl-quinolin-2(1H)-one acetates in moderate to good yields. Controlled experiments demonstrated that H₂O acted as both oxygen and hydrogen sources, and gem-dichlorovinyl carbonyl compound exhibited as a critical intermediate in this process. The mechanistic pathway involves Kharasch-type addition/6-exo-dig cyclization/1,5-(SN”)-substitution/elimination/binucleophilic 1,6-addition/proton transfer/tautomerization sequence. Full article

To achieve the peak of carbon dioxide emission and carbon neutrality, utilizing it as a renewable carbon unit in organic synthesis presents an effective chemical solution for sustainable development. In this study, we report a theoretical investigation into the reaction mechanism and the regiodivergence of the Ni-catalyzed [2+2+2] cycloaddition of unsymmetric diynes and CO₂ by using DFT calculations. The reaction mechanisms can be classified into two types: one is related to the oxidative coupling of the C≡C moiety with CO₂, and the other is related to the oxidative coupling of the two C≡C moieties of diyne. In each type, two possible paths were proposed depending upon the positions of the substituents (H and silyl). Our calculation results indicate that the oxidative coupling of the C≡C moiety and CO₂ favors the positions of H-substituent, while the oxidative coupling of the two C≡C moieties is beneficial for inserting CO₂ at the positions of silyl-substituent. The regiodivergence is controlled by substrate chain-length and ligand in the different reaction mechanisms. Full article

Stereoselective synthesis of (7Z,11Z)-octadeca-7,11-diene-1,18-dioic acid was carried out using a homo-cyclomagnesiation reaction of 2-(nona-7,8-dien-1-yloxy)tetrahydro-2H-pyran. After Steglisch esterification of the synthesized acid and polyester acetylenes in the presence of DCC and DMAP, the corresponding diesters were synthesized in good yields (67–75%). Based on symmetric diesters with terminal triple bonds, polyether macrodiolides containing conjugated triple bonds and pharmacophoric cis,cis-1,5-diene fragments in their structure were synthesized for the first time. Full article