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Molecules, Volume 21, Issue 11 (November 2016)

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Cover Story (view full-size image) Hypervalent pentacoordinated phosphoranes are an interesting class of organophosphorus compounds [...] Read more.
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Open AccessArticle Surface Modification of a Nanoporous Carbon Photoanode upon Irradiation
Molecules 2016, 21(11), 1611; https://doi.org/10.3390/molecules21111611
Received: 30 August 2016 / Revised: 4 November 2016 / Accepted: 15 November 2016 / Published: 23 November 2016
Cited by 3 | PDF Full-text (788 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
The photocorrosion of a nanoporous carbon photoanode, with low surface functionalization and high performance towards the photoelectrochemical oxidation of water using simulated solar light, was investigated. Two different light configurations were used to isolate the effect of the irradiation wavelength (UV and visible
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The photocorrosion of a nanoporous carbon photoanode, with low surface functionalization and high performance towards the photoelectrochemical oxidation of water using simulated solar light, was investigated. Two different light configurations were used to isolate the effect of the irradiation wavelength (UV and visible light) on the textural and chemical features of the carbon photoanode, and its long-term photocatalytic performance for the oxygen evolution reaction. A complete characterization of the carbon showed that the photocorrosion of carbon anodes of low functionalization follows a different pathway than highly functionalized carbons. The carbon matrix gets slightly oxidized, with the formation of carboxylic and carbonyl-like moieties in the surface of the carbon anode after light exposure. The oxidation of the carbon occurred due to the photogeneration of oxygen reactive species upon the decomposition of water during the irradiation of the photoanodes. Furthermore, the photoinduced surface reactions depend on the nature of the carbon anode and its ability to photogenerate reactive species in solution, rather than on the wavelength of the irradiation source. This surface modification is responsible for the decreased efficiency of the carbon photoanode throughout long illumination periods, due to the effect of the oxidation of the carbon matrix on the charge transfer. In this work, we have corroborated that, in the case of a low functionalization carbon material, the photocorrosion also occurs although it proceeds through a different pathway. The carbon anode gets gradually slightly oxidized due to the photogeneration of O-reactive species, being the incorporation of the O-groups responsible for the decreased performance of the anode upon long-term irradiation due to the effect of the oxidation of the carbon matrix on the electron transfer. Full article
(This article belongs to the Special Issue Solar Photocatalysis)
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Open AccessArticle Simultaneous Ultra Performance Liquid Chromatography Determination and Antioxidant Activity of Linarin, Luteolin, Chlorogenic Acid and Apigenin in Different Parts of Compositae Species
Molecules 2016, 21(11), 1609; https://doi.org/10.3390/molecules21111609
Received: 30 September 2016 / Revised: 11 November 2016 / Accepted: 17 November 2016 / Published: 23 November 2016
Cited by 4 | PDF Full-text (969 KB) | HTML Full-text | XML Full-text
Abstract
Linarin (LA), luteolin (LE), chlorogenic acid (CA) and apigenin (AP) are four major flavonoids with various promising bioactivities found in Compositae (COP) species. A reliable, reproducible and accurate method for the simultaneous and quantitative determination of these four major flavonoids by Ultra Performance
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Linarin (LA), luteolin (LE), chlorogenic acid (CA) and apigenin (AP) are four major flavonoids with various promising bioactivities found in Compositae (COP) species. A reliable, reproducible and accurate method for the simultaneous and quantitative determination of these four major flavonoids by Ultra Performance Liquid Chromatography (UPLC) analysis was developed. This method should be appropriate for the quality assurance of COP. The UPLC separation was carried out using an octadecylsilane (ODS) Hypersil (2.1 mm × 250 mm, 1.9 μm) and a mobile phase composed of acetonitrile and 0.1% formic acid in water at a flow rate 0.44 mL/min and ultraviolet (UV) detection 254 nm. Gradient elution was employed. The method was precise, with relative standard deviation below 3.0% and showed excellent linearity (R2 > 0.999). The recoveries for the four flavonoids in COP were between 95.49%–106.23%. The average contents of LA, LE, CA and AP in different parts (flower, leave and stem) of COP were between 0.64–1.47 g/100 g, 0.66–0.89 g/100 g, 0.32–0.52 g/100 g and 0.16–0.18 g/100 g, respectively. The method was accurate and reproducible and it can provide a quantitative basis for quality control of COP. Full article
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Open AccessReview Natural Compound Histone Deacetylase Inhibitors (HDACi): Synergy with Inflammatory Signaling Pathway Modulators and Clinical Applications in Cancer
Molecules 2016, 21(11), 1608; https://doi.org/10.3390/molecules21111608
Received: 28 September 2016 / Revised: 3 November 2016 / Accepted: 3 November 2016 / Published: 23 November 2016
Cited by 13 | PDF Full-text (37116 KB) | HTML Full-text | XML Full-text
Abstract
The remarkable complexity of cancer involving multiple mechanisms of action and specific organs led researchers Hanahan and Weinberg to distinguish biological capabilities acquired by cancer cells during the multistep development of human tumors to simplify its understanding. These characteristic hallmarks include the abilities
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The remarkable complexity of cancer involving multiple mechanisms of action and specific organs led researchers Hanahan and Weinberg to distinguish biological capabilities acquired by cancer cells during the multistep development of human tumors to simplify its understanding. These characteristic hallmarks include the abilities to sustain proliferative signaling, evade growth suppressors, resist cell death, enable replicative immortality, induce angiogenesis, activate invasion and metastasis, avoid immune destruction, and deregulate cellular energetics. Furthermore, two important characteristics of tumor cells that facilitate the acquisition of emerging hallmarks are tumor-promoting inflammation and genome instability. To treat a multifactorial disease such as cancer, a combination treatment strategy seems to be the best approach. Here we focus on natural histone deacetylase inhibitors (HDACi), their clinical uses as well as synergies with modulators of the pro-inflammatory transcription factor signaling pathways. Full article
(This article belongs to the Special Issue Natural Products and Inflammation)
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Open AccessArticle The Draft Genome Sequence of Actinokineospora bangkokensis 44EHWT Reveals the Biosynthetic Pathway of the Antifungal Thailandin Compounds with Unusual Butylmalonyl-CoA Extender Units
Molecules 2016, 21(11), 1607; https://doi.org/10.3390/molecules21111607
Received: 17 October 2016 / Revised: 17 November 2016 / Accepted: 19 November 2016 / Published: 23 November 2016
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Abstract
We report the draft genome sequence of Actinokineospora bangkokensis 44EHWT, the producer of the antifungal polyene compounds, thailandins A and B. The sequence contains 7.45 Mb, 74.1% GC content and 35 putative gene clusters for the biosynthesis of secondary metabolites. There
[...] Read more.
We report the draft genome sequence of Actinokineospora bangkokensis 44EHWT, the producer of the antifungal polyene compounds, thailandins A and B. The sequence contains 7.45 Mb, 74.1% GC content and 35 putative gene clusters for the biosynthesis of secondary metabolites. There are three gene clusters encoding large polyketide synthases of type I. Annotation of the ORF functions and targeted gene disruption enabled us to identify the cluster for thailandin biosynthesis. We propose a plausible biosynthetic pathway for thailandin, where the unusual butylmalonyl-CoA extender unit is incorporated and results in an untypical side chain. Full article
(This article belongs to the Special Issue Genomics-based Discovery of Microbial Natural Products)
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Open AccessArticle Chemical Constituents of Phaius mishmensis
Molecules 2016, 21(11), 1605; https://doi.org/10.3390/molecules21111605
Received: 5 October 2016 / Revised: 18 November 2016 / Accepted: 21 November 2016 / Published: 23 November 2016
Cited by 3 | PDF Full-text (789 KB) | HTML Full-text | XML Full-text
Abstract
The partitioned n-hexane, CHCl3, and EtOAc extracts from the crude MeOH extract of Phaius mishmensis showed considerable cytotoxicities against the human breast carcinoma (MCF-7), lung carcinoma (NCI-H460), and central nervous system carcinoma (SF-268) cell lines. Four new compounds, phaindole (
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The partitioned n-hexane, CHCl3, and EtOAc extracts from the crude MeOH extract of Phaius mishmensis showed considerable cytotoxicities against the human breast carcinoma (MCF-7), lung carcinoma (NCI-H460), and central nervous system carcinoma (SF-268) cell lines. Four new compounds, phaindole (1), (7′R,8′R)-phaithrene (2), methyl 3-hydroxy-4,5-dimethoxypropiophenone (3), and methyl hematinate (4), as well as 44 known compounds were isolated from the MeOH extract of Phaius mishmensis. The structures of the compounds were determined using spectroscopic methods. Full article
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Open AccessArticle AutoDock-GIST: Incorporating Thermodynamics of Active-Site Water into Scoring Function for Accurate Protein-Ligand Docking
Molecules 2016, 21(11), 1604; https://doi.org/10.3390/molecules21111604
Received: 12 October 2016 / Revised: 15 November 2016 / Accepted: 16 November 2016 / Published: 23 November 2016
Cited by 5 | PDF Full-text (5935 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Water plays a significant role in the binding process between protein and ligand. However, the thermodynamics of water molecules are often underestimated, or even ignored, in protein-ligand docking. Usually, the free energies of active-site water molecules are substantially different from those of waters
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Water plays a significant role in the binding process between protein and ligand. However, the thermodynamics of water molecules are often underestimated, or even ignored, in protein-ligand docking. Usually, the free energies of active-site water molecules are substantially different from those of waters in the bulk region. The binding of a ligand to a protein causes a displacement of these waters from an active site to bulk, and this displacement process substantially contributes to the free energy change of protein-ligand binding. The free energy of active-site water molecules can be calculated by grid inhomogeneous solvation theory (GIST), using molecular dynamics (MD) and the trajectory of a target protein and water molecules. Here, we show a case study of the combination of GIST and a docking program and discuss the effectiveness of the displacing gain of unfavorable water in protein-ligand docking. We combined the GIST-based desolvation function with the scoring function of AutoDock4, which is called AutoDock-GIST. The proposed scoring function was assessed employing 51 ligands of coagulation factor Xa (FXa), and results showed that both scoring accuracy and docking success rate were improved. We also evaluated virtual screening performance of AutoDock-GIST using FXa ligands in the directory of useful decoys-enhanced (DUD-E), thus finding that the displacing gain of unfavorable water is effective for a successful docking campaign. Full article
(This article belongs to the collection Molecular Docking)
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Open AccessArticle New Insights into the State Trapping of UV-Excited Thymine
Molecules 2016, 21(11), 1603; https://doi.org/10.3390/molecules21111603
Received: 12 October 2016 / Revised: 15 November 2016 / Accepted: 17 November 2016 / Published: 23 November 2016
Cited by 10 | PDF Full-text (3301 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
After UV excitation, gas phase thymine returns to a ground state in 5 to 7 ps, showing multiple time constants. There is no consensus on the assignment of these processes, with a dispute between models claiming that thymine is trapped either in the
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After UV excitation, gas phase thymine returns to a ground state in 5 to 7 ps, showing multiple time constants. There is no consensus on the assignment of these processes, with a dispute between models claiming that thymine is trapped either in the first (S1) or in the second (S2) excited states. In the present study, a nonadiabatic dynamics simulation of thymine is performed on the basis of ADC(2) surfaces, to understand the role of dynamic electron correlation on the deactivation pathways. The results show that trapping in S2 is strongly reduced in comparison to previous simulations considering only non-dynamic electron correlation on CASSCF surfaces. The reason for the difference is traced back to the energetic cost for formation of a CO π bond in S2. Full article
(This article belongs to the Special Issue Experimental and Computational Photochemistry of Bioorganic Molecules)
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Open AccessArticle Investigating Glycol-Split-Heparin-Derived Inhibitors of Heparanase: A Study of Synthetic Trisaccharides
Molecules 2016, 21(11), 1602; https://doi.org/10.3390/molecules21111602
Received: 25 October 2016 / Revised: 16 November 2016 / Accepted: 18 November 2016 / Published: 23 November 2016
Cited by 1 | PDF Full-text (1951 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Heparanase is the only known endoglycosidase able to cleave heparan sulfate. Roneparstat and necuparanib, heparanase inhibitors obtained from heparin and currently being tested in man as a potential drugs against cancer, contain in their structure glycol-split uronic acid moieties probably responsible for their
[...] Read more.
Heparanase is the only known endoglycosidase able to cleave heparan sulfate. Roneparstat and necuparanib, heparanase inhibitors obtained from heparin and currently being tested in man as a potential drugs against cancer, contain in their structure glycol-split uronic acid moieties probably responsible for their strong inhibitory activity. We describe here the total chemical synthesis of the trisaccharide GlcNS6S-GlcA-1,6anGlcNS (1) and its glycol-split (gs) counterpart GlcNS6S-gsGlcA-1,6anGlcNS (2) from glucose. As expected, in a heparanase inhibition assay, compound 2 is one order of magnitude more potent than 1. Using molecular modeling techniques we have created a 3D model of 1 and 2 that has been validated by NOESY NMR experiments. The pure synthetic oligosaccharides have allowed the first in depth study of the conformation of a glycol-split glucuronic acid. Introducing a glycol-split unit in the structure of 1 increases the conformational flexibility and shortens the distance between the two glucosamine motives, thus promoting interaction with heparanase. However, comparing the relative activities of 2 and roneparstat, we can conclude that the glycol-split motive is not the only determinant of the strong inhibitory effect of roneparstat. Full article
(This article belongs to the collection Advances in Carbohydrate Chemistry)
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Open AccessArticle Damxungmacin A and B, Two New Amicoumacins with Rare Heterocyclic Cores Isolated from Bacillus subtilis XZ-7
Molecules 2016, 21(11), 1601; https://doi.org/10.3390/molecules21111601
Received: 12 October 2016 / Revised: 13 November 2016 / Accepted: 20 November 2016 / Published: 23 November 2016
Cited by 1 | PDF Full-text (1363 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Two new amicoumacins, named Damxungmacin A (1) and B (2), were isolated from the culture broth of a soil-derived bacterium Bacillus subtilis XZ-7. Their chemical structures were elucidated by spectroscopic studies (UV, IR, NMR and HR-ESI-MS). Compound 1 possessed
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Two new amicoumacins, named Damxungmacin A (1) and B (2), were isolated from the culture broth of a soil-derived bacterium Bacillus subtilis XZ-7. Their chemical structures were elucidated by spectroscopic studies (UV, IR, NMR and HR-ESI-MS). Compound 1 possessed a 1,4-diazabicyclo[2.2.1]heptane-2-one ring system in its structure, which was reported for the first time, while 2 had a 1-acetylmorpholine-3-one moiety, which was naturally rare. Compound 1 exhibited moderate to weak cytotoxic activities against three human tumor cell lines (A549, HCT116 and HepG2) with IC50 values of 13.33, 14.34 and 13.64 μM, respectively. Meanwhile, compound 1 showed weak antibacterial activities against some strains of Staphylococcus epidermidis, while compound 2 at 16 μg/mL did not show antibacterial activity. Full article
(This article belongs to the Section Natural Products Chemistry)
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Open AccessReview 1-Deoxynojirimycin: Occurrence, Extraction, Chemistry, Oral Pharmacokinetics, Biological Activities and In Silico Target Fishing
Molecules 2016, 21(11), 1600; https://doi.org/10.3390/molecules21111600
Received: 13 October 2016 / Revised: 15 November 2016 / Accepted: 16 November 2016 / Published: 23 November 2016
Cited by 4 | PDF Full-text (1838 KB) | HTML Full-text | XML Full-text
Abstract
1-Deoxynojirimycin (DNJ, C6H13NO4, 163.17 g/mol), an alkaloid azasugar or iminosugar, is a biologically active natural compound that exists in mulberry leaves and Commelina communis (dayflower) as well as from several bacterial strains such as Bacillus and Streptomyces
[...] Read more.
1-Deoxynojirimycin (DNJ, C6H13NO4, 163.17 g/mol), an alkaloid azasugar or iminosugar, is a biologically active natural compound that exists in mulberry leaves and Commelina communis (dayflower) as well as from several bacterial strains such as Bacillus and Streptomyces species. Deoxynojirimycin possesses antihyperglycemic, anti-obesity, and antiviral features. Therefore, the aim of this detailed review article is to summarize the existing knowledge on occurrence, extraction, purification, determination, chemistry, and bioactivities of DNJ, so that researchers may use it to explore future perspectives of research on DNJ. Moreover, possible molecular targets of DNJ will also be investigated using suitable in silico approach. Full article
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Open AccessArticle Ligustrazine-Oleanolic Acid Glycine Derivative, G-TOA, Selectively Inhibited the Proliferation and Induced Apoptosis of Activated HSC-T6 Cells
Molecules 2016, 21(11), 1599; https://doi.org/10.3390/molecules21111599
Received: 30 August 2016 / Revised: 15 November 2016 / Accepted: 16 November 2016 / Published: 23 November 2016
Cited by 4 | PDF Full-text (6395 KB) | HTML Full-text | XML Full-text
Abstract
Hepatic fibrosis is a naturally occurring wound-healing reaction, with an imbalance of extracellular matrix (ECM) during tissue repair response, which can further deteriorate to hepatocellular carcinoma without timely treatment. Inhibiting activated hepatic stellate cell (HSC) proliferation and inducing apoptosis are the main methods
[...] Read more.
Hepatic fibrosis is a naturally occurring wound-healing reaction, with an imbalance of extracellular matrix (ECM) during tissue repair response, which can further deteriorate to hepatocellular carcinoma without timely treatment. Inhibiting activated hepatic stellate cell (HSC) proliferation and inducing apoptosis are the main methods for the treatment of liver fibrosis. In our previous study, we found that the TOA-glycine derivative (G-TOA) had exhibited more significant inhibitory activity against HepG2 cells and better hydrophilicity than TOA, ligustrazine (TMP), and oleanolic acid (OA). However, inhibiting activated HSC proliferation and inducing apoptosis by G-TOA had not been reported. In this paper, the selective cytotoxicity of G-TOA was evaluated on HSC-T6 cells and L02 cells, and apoptosis mechanisms were explored. It was found that G-TOA could selectively inhibit the proliferation of activated HSC-T6 cells, induce morphological changes, early apoptosis, and mitochondrial membrane potential depolarization, increase intracellular free calcium levels, downregulate the expression of NF-κB/p65 and COX-2 protein, and decrease the ratio of Bcl-2/Bax, thereby inducing HSC-T6 cell apoptosis. Thence, G-TOA might be a potential antifibrosis agent for the therapy of hepatic fibrosis, provided that it exerts anti-fibrosis effects on activated HSC-T6 cells. Full article
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Open AccessArticle Multi-Functional Nanogels for Tumor Targeting and Redox-Sensitive Drug and siRNA Delivery
Molecules 2016, 21(11), 1594; https://doi.org/10.3390/molecules21111594
Received: 4 August 2016 / Revised: 18 October 2016 / Accepted: 16 November 2016 / Published: 23 November 2016
Cited by 5 | PDF Full-text (8019 KB) | HTML Full-text | XML Full-text
Abstract
(1) Background: A new family of nanosystems able to discern between normal and tumor cells and to release a therapeutic agent in controlled way were synthetized by e-beam irradiation. This technique permits to obtain biocompatible, sterile, carboxyl-functionalized polyvinylpyrrolidone (PVP-co-acrylic acid) nanogels (NGs); (2)
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(1) Background: A new family of nanosystems able to discern between normal and tumor cells and to release a therapeutic agent in controlled way were synthetized by e-beam irradiation. This technique permits to obtain biocompatible, sterile, carboxyl-functionalized polyvinylpyrrolidone (PVP-co-acrylic acid) nanogels (NGs); (2) Methods: Here, we performed a targeting strategy based on the recognition of over-expressed proteins on tumor cells, like the folate receptor. The selective targeting was demonstrated by co-culture studies and flow cytometry analysis, using folate conjugated NGs. Moreover, nanoparticles were conjugated to a chemotherapeutic drug or to a pro-apoptotic siRNA through a glutathione sensitive spacer, in order to obtain a controlled release mechanism, specific for cancer cells. The drug efficiency was tested on tumor and healthy cells by flow cytometric analysis, confocal and epifluorescence microscopy and cytotoxicity assay; the siRNA effect was investigated by RNAi experiment; (3) Results: The data obtained showed that the use of NGs permits a faster cargo release in cancer cells, in response to high cytosolic glutathione level, also improving their efficacy; (4) Conclusion: The possibility of releasing biological molecules in a controlled way and to recognize a specific tumor target allows overcoming the typical limits of the classic cancer therapy. Full article
(This article belongs to the Special Issue Stimuli-Responsive Biomaterials in Biomedical Applications)
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Open AccessArticle Synthesis and Antifungal Screening of 2-{[1-(5-Alkyl/arylalkylpyrazin-2-yl)ethylidene]hydrazono}-1,3-thiazolidin-4-ones
Molecules 2016, 21(11), 1592; https://doi.org/10.3390/molecules21111592
Received: 30 September 2016 / Revised: 16 November 2016 / Accepted: 16 November 2016 / Published: 23 November 2016
PDF Full-text (701 KB) | HTML Full-text | XML Full-text
Abstract
Two novel thiosemicarbazones and eight novel 2-{[1-(5-alkyl/arylalkylpyrazin-2-yl)ethylidene]hydrazono}-1,3-thiazolidin-4-ones were prepared and tested against a panel of eight fungal strains–Candida albicans ATCC 44859, Candida tropicalis 156, Candida krusei E 28, Candida glabrata 20/I, Trichosporon asahii 1188, Aspergillus fumigatus 231, Lichtheimia corymbifera 272, and Trichophyton
[...] Read more.
Two novel thiosemicarbazones and eight novel 2-{[1-(5-alkyl/arylalkylpyrazin-2-yl)ethylidene]hydrazono}-1,3-thiazolidin-4-ones were prepared and tested against a panel of eight fungal strains–Candida albicans ATCC 44859, Candida tropicalis 156, Candida krusei E 28, Candida glabrata 20/I, Trichosporon asahii 1188, Aspergillus fumigatus 231, Lichtheimia corymbifera 272, and Trichophyton interdigitale 445. 1,3-Thiazolidin-4-ones exhibited activity against all strains, the most potent derivative was 2-{[1-(5-butylpyrazin-2-yl)ethylidene]hydrazono}e-1,3-thiazolidin-4-one. Susceptibility of C. glabrata to the studied 1,3-thiazolidin-4-ones (minimum inhibitory concentrations (MICs) were in the range 0.57 to 2.78 mg/L) is of great interest as this opportunistic pathogen is poorly susceptible to azoles and becomes resistant to echinocandins. Antifungal potency of thiosemicarbazones was slightly lower than that of 1,3-thiazolidin-4-ones. Full article
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Open AccessArticle Chemoenzymatic Synthesis of trans-β-Aryl-δ-hydroxy-γ-lactones and Enzymatic Kinetic Resolution of Their Racemic Mixtures
Molecules 2016, 21(11), 1552; https://doi.org/10.3390/molecules21111552
Received: 11 October 2016 / Revised: 7 November 2016 / Accepted: 11 November 2016 / Published: 23 November 2016
Cited by 1 | PDF Full-text (953 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Two novel and convenient routes to obtain enantiomerically enriched trans-β-aryl-δ-hydroxy-γ-lactones 5ad with potential antifeedant and anticancer activity were developed. In the first method starting from corresponding enantiomers of γ,δ-unsaturated esters 4ad derived from enzymatically resolved allyl alcohols 1a
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Two novel and convenient routes to obtain enantiomerically enriched trans-β-aryl-δ-hydroxy-γ-lactones 5ad with potential antifeedant and anticancer activity were developed. In the first method starting from corresponding enantiomers of γ,δ-unsaturated esters 4ad derived from enzymatically resolved allyl alcohols 1ad, both enantiomers of hydroxylactones 5ad were synthesized with high enantiomeric excesses (73%–97%). Configurations of the stereogenic centers of the synthesized compounds were assigned based on the mechanism of acidic lactonization of esters 4ad in the presence of m-chloroperbenzoic acid (m-CPBA). An alternative method for the production of optically active trans-β-aryl-δ-hydroxy-γ-lactones 5ad was lipase-catalyzed kinetic resolution of their racemic mixtures by transesterification with vinyl propionate as the acyl donor. The most efficient enzyme in the screening procedure was lipase B from Candida antarctica. Its application on a preparative scale after 6 h afforded unreacted (+)-(4S,5R,6S)-hydroxylactones 5ad and (+)-(4R,5S,6R)-propionates 6ad, most of them with high enantiomeric excesses (92%–98%). Resolution of lactone 5d with bulky 1,3-benzodioxol ring provided products with significantly lower optical purity (ee = 89% and 84% for hydroxylactone 5d and propionate 6d, respectively). The elaborated methods give access to both enantiomers of trans-β-aryl-δ-hydroxy-γ-lactones 5ad with the defined absolute configurations of stereogenic centers, which is crucial requirement for the investigations of relationship: spatial structure–biological activity. Full article
(This article belongs to the Section Organic Chemistry)
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Open AccessArticle Synthesis, Characterization, and Anti-Inflammatory Activities of Methyl Salicylate Derivatives Bearing Piperazine Moiety
Molecules 2016, 21(11), 1544; https://doi.org/10.3390/molecules21111544
Received: 11 October 2016 / Revised: 10 November 2016 / Accepted: 11 November 2016 / Published: 23 November 2016
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Abstract
In this study, a new series of 16 methyl salicylate derivatives bearing a piperazine moiety were synthesized and characterized. The in vivo anti-inflammatory activities of target compounds were investigated against xylol-induced ear edema and carrageenan-induced paw edema in mice. The results showed that
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In this study, a new series of 16 methyl salicylate derivatives bearing a piperazine moiety were synthesized and characterized. The in vivo anti-inflammatory activities of target compounds were investigated against xylol-induced ear edema and carrageenan-induced paw edema in mice. The results showed that all synthesized compounds exhibited potent anti-inflammatory activities. Especially, the anti-inflammatory activities of compounds M15 and M16 were higher than that of aspirin and even equal to that of indomethacin at the same dose. In addition, the in vitro cytotoxicity activities and anti-inflammatory activities of four target compounds were performed in RAW264.7 macrophages, and compound M16 was found to significantly inhibit the release of lipopolysaccharide (LPS)-induced interleukin (IL)-6 and tumor necrosis factor (TNF)-α in a dose-dependent manner. In addition, compound M16 was found to attenuate LPS induced cyclooxygenase (COX)-2 up-regulation. The current preliminary study may provide information for the development of new and safe anti-inflammatory agents. Full article
(This article belongs to the Section Medicinal Chemistry)
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Open AccessArticle Synthesis and Evaluation of New Benzodioxole- Based Thiosemicarbazone Derivatives as Potential Antitumor Agents
Molecules 2016, 21(11), 1598; https://doi.org/10.3390/molecules21111598
Received: 22 July 2016 / Revised: 16 November 2016 / Accepted: 18 November 2016 / Published: 22 November 2016
Cited by 5 | PDF Full-text (2414 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
New benzodioxole-based thiosemicarbazone derivatives were synthesized and evaluated for their cytotoxic effects on A549 human lung adenocarcinoma, C6 rat glioma and NIH/3T3 mouse embryonic fibroblast cells. In order to examine the correlation between anticancer activity and cholinesterases, the compounds were evaluated for their
[...] Read more.
New benzodioxole-based thiosemicarbazone derivatives were synthesized and evaluated for their cytotoxic effects on A549 human lung adenocarcinoma, C6 rat glioma and NIH/3T3 mouse embryonic fibroblast cells. In order to examine the correlation between anticancer activity and cholinesterases, the compounds were evaluated for their inhibitory effects on AChE and BuChE. The most effective anticancer agents were investigated for their effects on DNA synthesis, apoptosis and mitochondrial membrane potential. 4-(1,3-Benzodioxol-5-yl)-1-([1,1′-biphenyl]-4-ylmethylene)thiosemicarbazide (5) was identified as the most promising anticancer agent against C6 and A549 cell lines due to its inhibitory effects on C6 and A549 cells and low toxicity to NIH/3T3 cells. Compound 5 increased early and late apoptosis in A549 and C6 cells. Compound 5 also caused disturbance on mitochondrial membrane potential and showed DNA synthesis inhibitory activity in A549 and C6 cells. Compound 5 was investigated for SIRT1 inhibitory activity to provide mechanistic insight and for that purpose docking studies were also performed for this compound on SIRT1. On the other hand, compound 5 did not show any inhibitory activity against AChE and BuChE. This outcome pointed out that there is no relationship between anticancer activity of compound 5 and cholinesterases. Full article
(This article belongs to the Section Medicinal Chemistry)
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Open AccessArticle Kuwanon G Preserves LPS-Induced Disruption of Gut Epithelial Barrier In Vitro
Molecules 2016, 21(11), 1597; https://doi.org/10.3390/molecules21111597
Received: 6 October 2016 / Revised: 13 November 2016 / Accepted: 17 November 2016 / Published: 22 November 2016
Cited by 8 | PDF Full-text (2433 KB) | HTML Full-text | XML Full-text
Abstract
Defects in the gut epithelial barrier have now been recognized to be responsible for diabetic endotoxemia. In everyday life, Mulberry leaf tea is widely used in Asian nations due to its proposed benefits to health and control of diabetes. Evidence indicates the potential
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Defects in the gut epithelial barrier have now been recognized to be responsible for diabetic endotoxemia. In everyday life, Mulberry leaf tea is widely used in Asian nations due to its proposed benefits to health and control of diabetes. Evidence indicates the potential role of Kuwanon G (KWG), a component from Morus alba L., on blocking the gut epithelial barrier. In lipopolysaccharides (LPS)-damaged Caco-2 cells, it was found that KWG increased the viability of cells in a concentration-dependent manner. KWG administration significantly elevated the anti-oxidant abilities via increasing ratio of superoxidase dismutase (SOD)/malondialdehyde (MDA) and decreasing reactive oxygen species (ROS) within the cells. During KWG incubation, pro-inflammatory cytokines including interleukin (IL)-1β and tumor necrosis factor (TNF)-α were significantly reduced, tight junction proteins including zonula occludens (ZO)-1, intercellular adhesion molecule (ICAM)-1 and Occludin were dramatically increased as detected by immunofluorescence assay, trans-epithelial electrical resistance was significantly increased and the transmission of albumin-fluorescein isothiocyanate (FITC) across the barrier was decreased. In conclusion, the present study demonstrated that KWG could ameliorate LPS-induced disruption of the gut epithelial barrier by increasing cell viability and tight junction between cells, and decreasing pro-inflammatory cytokines and oxidative damage. Full article
(This article belongs to the Special Issue Natural Products and Chronic Diseases)
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Open AccessReview 4-Hydroxyisoleucine from Fenugreek (Trigonella foenum-graecum): Effects on Insulin Resistance Associated with Obesity
Molecules 2016, 21(11), 1596; https://doi.org/10.3390/molecules21111596
Received: 5 September 2016 / Revised: 31 October 2016 / Accepted: 10 November 2016 / Published: 22 November 2016
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Abstract
Obesity and insulin resistance (IR) are interdependent multifactorial processes that cannot be understood separately. Obesity leads to systemic inflammation and increased levels of free fatty acids that provoke IR and lipotoxicity. At the same time, IR exacerbates adipose cell dysfunction, resulting in chronic
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Obesity and insulin resistance (IR) are interdependent multifactorial processes that cannot be understood separately. Obesity leads to systemic inflammation and increased levels of free fatty acids that provoke IR and lipotoxicity. At the same time, IR exacerbates adipose cell dysfunction, resulting in chronic inflammation and major lipotoxic effects on nonadipose tissues. 4-Hydroxyisoleucine (4-OHIle), a peculiar nonprotein amino acid isolated from fenugreek (Trigonella foenum-graecum) seeds, exhibits interesting effects on IR related to obesity. 4-OHIle increases glucose-induced insulin release, and the insulin response mediated by 4-OHIle depends on glucose concentration. The beneficial effects observed are related to the regulation of blood glucose, plasma triglycerides, total cholesterol, free fatty acid levels, and the improvement of liver function. The mechanism of action is related to increased Akt phosphorylation and reduced activation of Jun N-terminal kinase (JNK)1/2, extracellular signal-regulated kinase (ERK)1/2, p38 mitogen-activated protein kinase (MAPK), and nuclear factor (NF)-κB. Here, we present a review of the research regarding the insulinotropic and insulin-sensitising activity of 4-OHIle in in vitro and in vivo models. Full article
(This article belongs to the Special Issue Natural Products in Anti-Obesity Therapy)
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Open AccessArticle New Thiazolyl-triazole Schiff Bases: Synthesis and Evaluation of the Anti-Candida Potential
Molecules 2016, 21(11), 1595; https://doi.org/10.3390/molecules21111595
Received: 31 October 2016 / Revised: 14 November 2016 / Accepted: 17 November 2016 / Published: 22 November 2016
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Abstract
In the context of the dangerous phenomenon of fungal resistance to the available therapies, we present here the chemical synthesis of a new series of thiazolyl-triazole Schiff bases B1B15, which were in vitro assessed for their anti-Candida potential. Compound
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In the context of the dangerous phenomenon of fungal resistance to the available therapies, we present here the chemical synthesis of a new series of thiazolyl-triazole Schiff bases B1B15, which were in vitro assessed for their anti-Candida potential. Compound B10 was found to be more potent against Candida spp. when compared with the reference drugs Fluconazole and Ketoconazole. A docking study of the newly synthesized Schiff bases was performed, and results showed good binding affinity in the active site of co-crystallized Itraconazole-lanosterol 14α-demethylase isolated from Saccharomyces cerevisiae. An in silico ADMET (absorption, distribution, metabolism, excretion, toxicity) study was done in order to predict some pharmacokinetic and pharmacotoxicological properties. The Schiff bases showed good drug-like properties. The results of in vitro anti-Candida activity, a docking study and ADMET prediction revealed that the newly synthesized compounds have potential anti-Candida activity and evidenced the most active derivative, B10, which can be further optimized as a lead compound. Full article
(This article belongs to the Special Issue Sulfur-Nitrogen Heteroaromatics)
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Open AccessArticle Stereoselective Alkane Oxidation with meta-Chloroperoxybenzoic Acid (MCPBA) Catalyzed by Organometallic Cobalt Complexes
Molecules 2016, 21(11), 1593; https://doi.org/10.3390/molecules21111593
Received: 23 October 2016 / Revised: 15 November 2016 / Accepted: 16 November 2016 / Published: 22 November 2016
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Abstract
Cobalt pi-complexes, previously described in the literature and specially synthesized and characterized in this work, were used as catalysts in homogeneous oxidation of organic compounds with peroxides. These complexes contain pi-butadienyl and pi-cyclopentadienyl ligands: [(tetramethylcyclobutadiene)(benzene)cobalt] hexafluorophosphate, [(C4Me4)Co(C6H
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Cobalt pi-complexes, previously described in the literature and specially synthesized and characterized in this work, were used as catalysts in homogeneous oxidation of organic compounds with peroxides. These complexes contain pi-butadienyl and pi-cyclopentadienyl ligands: [(tetramethylcyclobutadiene)(benzene)cobalt] hexafluorophosphate, [(C4Me4)Co(C6H6)]PF6 (1); diiodo(carbonyl)(pentamethylcyclopentadienyl)cobalt, Cp*Co(CO)I2 (2); diiodo(carbonyl)(cyclopentadienyl)cobalt, CpCo(CO)I2 (3); (tetramethylcyclobutadiene)(dicarbonyl)(iodo)cobalt, (C4Me4)Co(CO)2I (4); [(tetramethylcyclobutadiene)(acetonitrile)(2,2′-bipyridyl)cobalt] hexafluorophosphate, [(C4Me4)Co(bipy)(MeCN)]PF6 (5); bis[dicarbonyl(B-cyclohexylborole)]cobalt, [(C4H4BCy)Co(CO)2]2 (6); [(pentamethylcyclopentadienyl)(iodo)(1,10-phenanthroline)cobalt] hexafluorophosphate, [Cp*Co(phen)I]PF6 (7); diiodo(cyclopentadienyl)cobalt, [CpCoI2]2 (8); [(cyclopentadienyl)(iodo)(2,2′-bipyridyl)cobalt] hexafluorophosphate, [CpCo(bipy)I]PF6 (9); and [(pentamethylcyclopentadienyl)(iodo)(2,2′-bipyridyl)cobalt] hexafluorophosphate, [Cp*Co(bipy)I]PF6 (10). Complexes 1 and 2 catalyze very efficient and stereoselective oxygenation of tertiary C–H bonds in isomeric dimethylcyclohexanes with MCBA: cyclohexanols are produced in 39 and 53% yields and with the trans/cis ratio (of isomers with mutual trans- or cis-configuration of two methyl groups) 0.05 and 0.06, respectively. Addition of nitric acid as co-catalyst dramatically enhances both the yield of oxygenates and stereoselectivity parameter. In contrast to compounds 1 and 2, complexes 9 and 10 turned out to be very poor catalysts (the yields of oxygenates in the reaction with cis-1,2-dimethylcyclohexane were only 5%–7% and trans/cis ratio 0.8 indicated that the oxidation is not stereoselective). The chromatograms of the reaction mixture obtained before and after reduction with PPh3 are very similar, which testifies that alkyl hydroperoxides are not formed in this oxidation. It can be thus concluded that the interaction of the alkanes with MCPBA occurs without the formation of free radicals. The complexes catalyze oxidation of alcohols with tert-butylhydroperoxide (TBHP). For example, tert-BuOOH efficiently oxidizes 1-phenylethanol to acetophenone in 98% yield if compound 1 is used as a catalyst. Full article
(This article belongs to the Special Issue Reactions of Hydrocarbons and other C‒H Compounds)
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Open AccessArticle Structural Analysis of Sortase A Inhibitors
Molecules 2016, 21(11), 1591; https://doi.org/10.3390/molecules21111591
Received: 25 October 2016 / Revised: 12 November 2016 / Accepted: 19 November 2016 / Published: 22 November 2016
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Abstract
Bacterial sortases are cysteine transpeptidases that regulate the covalent linkage of several surface protein virulence factors in Gram-positive bacteria. Virulence factors play significant roles in adhesion, invasion of host tissues, biofilm formation and immune evasion, mediating the bacterial pathogenesis and infectivity. Therefore, sortases
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Bacterial sortases are cysteine transpeptidases that regulate the covalent linkage of several surface protein virulence factors in Gram-positive bacteria. Virulence factors play significant roles in adhesion, invasion of host tissues, biofilm formation and immune evasion, mediating the bacterial pathogenesis and infectivity. Therefore, sortases are emerging as important targets for the design of new anti-infective agents. We employed a computational study, based on structure derived descriptors and molecular fingerprints, in order to develop simple classification methods which could allow predicting low active or high active SrtA inhibitors. Our results indicate that a highly active SrtA inhibitor has a molecular weight ranging between 180 and 600, contains one up to four nitrogen atoms, up to three oxygen atoms and under 18 hydrogen atoms. Also the hydrogen acceptor number and the molecular flexibility, as assessed by the number of rotatable bounds, have emerged as the most relevant descriptors for SrtA affinity. The Bemis-Murcko scaffolding revealed favoured scaffolds as containing at least two ring structures bonded directly or merged in a condensed cycle. This data represent a valuable tool for identifying new potent SrtA inhibitors, potential anti-virulence agents targeted against Gram-positive bacteria, including multiresistant strains. Full article
(This article belongs to the Special Issue Frontiers in Antimicrobial Drug Discovery and Design)
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Open AccessArticle Synthesis of a Morpholino Nucleic Acid (MNA)-Uridine Phosphoramidite, and Exon Skipping Using MNA/2′-O-Methyl Mixmer Antisense Oligonucleotide
Molecules 2016, 21(11), 1582; https://doi.org/10.3390/molecules21111582
Received: 21 September 2016 / Revised: 11 November 2016 / Accepted: 16 November 2016 / Published: 22 November 2016
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Abstract
In this study, we synthesised a morpholino nucleoside-uridine (MNA-U) phosphoramidite and evaluated the potential of a MNA-modified antisense oligonucleotide (AO) sequences to induce exon 23 skipping in mdx mouse myotubes in vitro towards extending the applicability of morpholino chemistry with other nucleotide monomers.
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In this study, we synthesised a morpholino nucleoside-uridine (MNA-U) phosphoramidite and evaluated the potential of a MNA-modified antisense oligonucleotide (AO) sequences to induce exon 23 skipping in mdx mouse myotubes in vitro towards extending the applicability of morpholino chemistry with other nucleotide monomers. We designed, synthesised, and compared exon skipping efficiencies of 20 mer MNA-modified 2′-O-methyl RNA mixmer AO on a phosphorothioate backbone (MNA/2′-OMePS) to the corresponding fully modified 2′-O-methyl RNA AO (2′-OMePS) as a control. Our results showed that the MNA/2′-OMePS efficiently induced exon 23 skipping. As expected, the 2′-OMePS AO control yielded efficient exon 23 skipping. Under the applied conditions, both the AOs showed minor products corresponding to exon 22/23 dual exon skipping in low yield. As these are very preliminary data, more detailed studies are necessary; however, based on the preliminary results, MNA nucleotides might be useful in constructing antisense oligonucleotides. Full article
(This article belongs to the Special Issue Nucleic Acid-based Drug)
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Open AccessArticle A Comparative Study of Enantioseparations of Nα-Fmoc Proteinogenic Amino Acids on Quinine-Based Zwitterionic and Anion Exchanger-Type Chiral Stationary Phases under Hydro-Organic Liquid and Subcritical Fluid Chromatographic Conditions
Molecules 2016, 21(11), 1579; https://doi.org/10.3390/molecules21111579
Received: 21 October 2016 / Revised: 15 November 2016 / Accepted: 17 November 2016 / Published: 22 November 2016
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Abstract
The focus of this contribution is a comparative investigation of enantioseparations of 19 Nα-Fmoc proteinogenic amino acids on Quinine-based zwitterionic and anion-exchanger type chiral stationary phases employing hydro-organic and polar-ionic liquid and subcritical fluid chromatographic conditions. Effects of mobile phase
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The focus of this contribution is a comparative investigation of enantioseparations of 19 Nα-Fmoc proteinogenic amino acids on Quinine-based zwitterionic and anion-exchanger type chiral stationary phases employing hydro-organic and polar-ionic liquid and subcritical fluid chromatographic conditions. Effects of mobile phase composition (including additives, e.g., water, basis and acids) and nature of chiral selectors on the chromatographic performances were studied at different chromatographic modes. Thermodynamic parameters of the temperature dependent enantioseparation results were calculated in the temperature range 5–50 °C applying plots of lnα versus 1/T. The differences in standard enthalpy and standard entropy for a given pair of enantiomers were calculated and served as a basis for comparisons. Elution sequence in all cases was determined, where a general rule could be observed, both in liquid and subcritical fluid chromatographic mode the d-enantiomers eluted before the L ones. In both modes, the principles of ion exchange chromatography apply. Full article
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Open AccessArticle Synthesis and Biological Evaluation of Benzimidazole Phenylhydrazone Derivatives as Antifungal Agents against Phytopathogenic Fungi
Molecules 2016, 21(11), 1574; https://doi.org/10.3390/molecules21111574
Received: 13 October 2016 / Revised: 8 November 2016 / Accepted: 12 November 2016 / Published: 22 November 2016
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Abstract
A series of benzimidazole phenylhydrazone derivatives (6a6ai) were synthesized and characterized by 1H-NMR, ESI-MS, and elemental analysis. The structure of 6b was further confirmed by single crystal X-ray diffraction as (E)-configuration. All the compounds were screened
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A series of benzimidazole phenylhydrazone derivatives (6a6ai) were synthesized and characterized by 1H-NMR, ESI-MS, and elemental analysis. The structure of 6b was further confirmed by single crystal X-ray diffraction as (E)-configuration. All the compounds were screened for antifungal activity against Rhizoctonia solani and Magnaporthe oryzae employing a mycelium growth rate method. Compound 6f exhibited significant inhibitory activity against R. solani and M. oryzae with the EC50 values of 1.20 and 1.85 μg/mL, respectively. In vivo testing demonstrated that 6f could effectively control the development of rice sheath blight (RSB) and rice blast (RB) caused by the above two phytopathogens. This work indicated that the compound 6f with a benzimidazole phenylhydrazone scaffold could be considered as a leading structure for the development of novel fungicides. Full article
(This article belongs to the Special Issue Frontiers in Antimicrobial Drug Discovery and Design)
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Open AccessArticle The Protective Effects of Icariin against the Homocysteine-Induced Neurotoxicity in the Primary Embryonic Cultures of Rat Cortical Neurons
Molecules 2016, 21(11), 1557; https://doi.org/10.3390/molecules21111557
Received: 22 July 2016 / Revised: 26 October 2016 / Accepted: 9 November 2016 / Published: 22 November 2016
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Abstract
Icariin, an ingredient in the medicinal herb Epimedium brevicornum Maxim (EbM), has been considered as a potential therapeutic agent for neurodegenerative diseases such as Alzheimer’s disease (AD). Hyperhomocysteinaemia is a risk factor for AD and other associated neurological diseases. In this
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Icariin, an ingredient in the medicinal herb Epimedium brevicornum Maxim (EbM), has been considered as a potential therapeutic agent for neurodegenerative diseases such as Alzheimer’s disease (AD). Hyperhomocysteinaemia is a risk factor for AD and other associated neurological diseases. In this study we aim to investigate whether icariin can reverse homocysteine (Hcy)-induced neurotoxicity in primary embryonic cultures of rat cortical neurons. Our findings demonstrated that icariin might be able restore the cytoskeleton network damaged by Hcy through the modulation of acetyl-α-tubulin, tyrosinated-α-tubulin, and phosphorylation of the tubulin-binding protein Tau. In addition, icariin downregulated p-extracellular signal-regulated kinase (ERK) which is a kinase targeting tau protein. Furthermore, icariin effectively restored the neuroprotective protein p-Akt that was downregulated by Hcy. We also applied RT2 Profiler PCR Arrays focused on genes related to AD and neurotoxicity to examine genes differentially altered by Hcy or icariin. Among the altered genes from the arrays, ADAM9 was downregulated 15 folds in cells treated with Hcy, but markedly restored by icariin. ADAM family, encoded α-secreatase, plays a protective role in AD. Overall, our findings demonstrated that icariin exhibits a strong neuroprotective function and have potential for future development for drug treating neurological disorders, such as AD. Full article
(This article belongs to the Section Natural Products Chemistry)
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Open AccessArticle New Homoisoflavanes, a New Alkaloid and Spirostane Steroids from the Roots of Herreria montevidensis Klotzsch ex Griseb. (Herreriaceae)
Molecules 2016, 21(11), 1589; https://doi.org/10.3390/molecules21111589
Received: 15 September 2016 / Revised: 12 November 2016 / Accepted: 17 November 2016 / Published: 21 November 2016
PDF Full-text (558 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
The roots of the South American vine Herreria montevidensis Klotzsch ex Griseb. (Herreriaceae) are used in traditional medicine by several Amerindian groups of the Paraguayan Chaco. Little is known on the chemistry of the plant, despite its widespread use across the South American
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The roots of the South American vine Herreria montevidensis Klotzsch ex Griseb. (Herreriaceae) are used in traditional medicine by several Amerindian groups of the Paraguayan Chaco. Little is known on the chemistry of the plant, despite its widespread use across the South American Chaco. From the ethyl acetate/methanol 1:1 extract of the roots, four new and one known homoisoflavanoid, two flavan derivatives, a stilbene, a new alkaloid, and three new and four known spirostane steroids were isolated. The corresponding structures were elucidated by spectroscopic and spectrometric means. The homoisoflavonoids of the plant are related to compounds isolated from the Dracaenaceae (formerly Agavaceae) sources of the Chinese crude drug Dragon’s Blood. The new alkaloid is a novel skeleton that can be used as a chemical marker of Herreria. The spirostane steroids suggest chemotaxonomic relations with the Liliales. This is the first comprehensive report on the chemistry of a South American Herreria species. Full article
(This article belongs to the Section Natural Products Chemistry)
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Open AccessReview Structures and Ribosomal Interaction of Ribosome-Inactivating Proteins
Molecules 2016, 21(11), 1588; https://doi.org/10.3390/molecules21111588
Received: 10 October 2016 / Revised: 9 November 2016 / Accepted: 15 November 2016 / Published: 21 November 2016
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Abstract
Ribosome-inactivating proteins (RIPs) including ricin, Shiga toxin, and trichosanthin, are RNA N-glycosidases that depurinate a specific adenine residue (A-4324 in rat 28S ribosomal RNA, rRNA) in the conserved α-sarcin/ricin loop (α-SRL) of rRNA. RIPs are grouped into three types according to the
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Ribosome-inactivating proteins (RIPs) including ricin, Shiga toxin, and trichosanthin, are RNA N-glycosidases that depurinate a specific adenine residue (A-4324 in rat 28S ribosomal RNA, rRNA) in the conserved α-sarcin/ricin loop (α-SRL) of rRNA. RIPs are grouped into three types according to the number of subunits and the organization of the precursor sequences. RIPs are two-domain proteins, with the active site located in the cleft between the N- and C-terminal domains. It has been found that the basic surface residues of the RIPs promote rapid and specific targeting to the ribosome and a number of RIPs have been shown to interact with the C-terminal regions of the P proteins of the ribosome. At present, the structural basis for the interaction of trichosanthin and ricin-A chain toward P2 peptide is known. This review surveys the structural features of the representative RIPs and discusses how they approach and interact with the ribosome. Full article
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Open AccessArticle Structural Investigation of Cell Wall Xylan Polysaccharides from the Leaves of Algerian Argania spinosa
Molecules 2016, 21(11), 1587; https://doi.org/10.3390/molecules21111587
Received: 6 October 2016 / Revised: 16 November 2016 / Accepted: 16 November 2016 / Published: 21 November 2016
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Abstract
Xylan-type polysaccharides were isolated from the leaves of Argania spinosa (L.) Skeels collected in the Tindouf area (southwestern Algeria). Xylan fractions were obtained by sequential alkaline extractions and purified on Sepharose CL-4B. The xylan structure was investigated by enzymatic hydrolysis with an endo-β(1→4)-xylanase
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Xylan-type polysaccharides were isolated from the leaves of Argania spinosa (L.) Skeels collected in the Tindouf area (southwestern Algeria). Xylan fractions were obtained by sequential alkaline extractions and purified on Sepharose CL-4B. The xylan structure was investigated by enzymatic hydrolysis with an endo-β(1→4)-xylanase followed by chromatography of the resulting fragments on Biogel P2, characterization by sugar analysis and matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS ). The results show that the A. spinosa xylan is composed of a β-(1→4)-d-xylopyranose backbone substituted with 4-O-methyl-d-glucuronic acid and L-arabinose residues. Full article
(This article belongs to the Special Issue Natural Polysaccharides)
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Open AccessArticle Bio-Guided Isolation of Methanol-Soluble Metabolites of Common Spruce (Picea abies) Bark by-Products and Investigation of Their Dermo-Cosmetic Properties
Molecules 2016, 21(11), 1586; https://doi.org/10.3390/molecules21111586
Received: 18 October 2016 / Revised: 13 November 2016 / Accepted: 15 November 2016 / Published: 21 November 2016
Cited by 4 | PDF Full-text (2038 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Common spruce (Picea abies L.) is a fast-growing coniferous tree, widely used in several countries for the production of sawn wood, timber and pulp. During this industrial exploitation, large quantities of barks are generated as waste materials. The aim of this study
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Common spruce (Picea abies L.) is a fast-growing coniferous tree, widely used in several countries for the production of sawn wood, timber and pulp. During this industrial exploitation, large quantities of barks are generated as waste materials. The aim of this study was the bio-guided investigation and the effective recovery of methanol-soluble metabolites of common spruce bark for the development of new dermo-cosmetic agents. The active methanol extract was initially fractionated by Centrifugal Partition Chromatography (CPC) using a triphasic solvent system in a step-gradient elution mode. All resulting fractions were evaluated for their antibacterial activity, antioxidant activity and their capability to inhibit tyrosinase, elastase and collagenase activity. In parallel, the chemical composition of each fraction was established by combining a 13C-NMR dereplication approach and 2D-NMR analyses. As a result, fourteen secondary metabolites corresponding to stilbene, flavonoid and phenolic acid derivatives were directly identified in the CPC fractions. A high amount (0.93 g) of E-astringin was recovered from 3 g of crude extract in a single 125 min run. E-Astringin significantly induced the tyrosinase activity while E-piceid, taxifolin, and taxifolin-3′-O-glucopyranoside exhibited significant anti-tyrosinase activity. The above compounds showed important anti-collagenase and antimicrobial activities, thus providing new perspectives for potential applications as cosmetic ingredients. Full article
(This article belongs to the Section Natural Products Chemistry)
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Open AccessArticle Temperature-Triggered Switchable Helix-Helix Inversion of Poly(phenylacetylene) Bearing l-Valine Ethyl Ester Pendants and Its Chiral Recognition Ability
Molecules 2016, 21(11), 1583; https://doi.org/10.3390/molecules21111583
Received: 10 October 2016 / Revised: 15 November 2016 / Accepted: 16 November 2016 / Published: 21 November 2016
Cited by 10 | PDF Full-text (3661 KB) | HTML Full-text | XML Full-text
Abstract
A phenylacetylene containing the l-valine ethyl ester pendant (PAA-Val) was synthesized and polymerized by an organorhodium catalyst (Rh(nbd)BPh4) to produce the corresponding one-handed helical cis-poly(phenylacetylene) (PPAA-Val). PPAA-Val showed a unique temperature-triggered switchable helix-sense in chloroform, while it was not
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A phenylacetylene containing the l-valine ethyl ester pendant (PAA-Val) was synthesized and polymerized by an organorhodium catalyst (Rh(nbd)BPh4) to produce the corresponding one-handed helical cis-poly(phenylacetylene) (PPAA-Val). PPAA-Val showed a unique temperature-triggered switchable helix-sense in chloroform, while it was not observed in highly polar solvents, such as N,N′-dimethylformamide (DMF). By heating the solution of PPAA-Val in chloroform, the sign of the CD absorption became reversed, but recovered after cooling the solution to room temperature. Even after six cycles of the heating-cooling treatment, the helix sense of the PPAA-Val’s backbone was still switchable without loss of the CD intensity. The PPAA-Val was then coated on silica gel particles to produce novel chiral stationary phases (CSPs) for high-performance liquid chromatography (HPLC). These novel PPAA-Val based CSPs showed a high chiral recognition ability for racemic mandelonitrile (α = 2.18) and racemic trans-N,N′-diphenylcyclohexane-1,2-dicarboxamide (α = 2.60). Additionally, the one-handed helical cis-polyene backbone of PPAA-Val was irreversibly destroyed to afford PPAA-Val-H by heating in dimethyl sulfoxide (DMSO) accompanied by the complete disappearance of the Cotton effect. Although PPAA-Val-H had the same l-valine ethyl ester pendants as its cis-isomer PPAA-Val, it showed no chiral recognition. It was concluded that the one-handed helical cis-polyene backbone of PPAA-Val plays an important role in the chiral recognition ability. Full article
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