Chemoenzymatic Asymmetric Synthesis of Chiral Triazole Fungicide (R)-Tebuconazole in High Optical Purity Mediated by an Epoxide Hydrolase from Rhodotorula paludigensis.

Tebuconazole is a chiral triazole fungicide used globally in agriculture as a racemic mixture, but its enantiomers exhibit significant enantioselective dissimilarities in bioactivity and environmental behaviors. The steric hindrance caused by the tert-butyl group makes it a great challenge to synthesize tebuconazole enantiomers. Here, we designed a simple chemoenzymatic approach for the asymmetric synthesis of (R)-tebuconazole, which includes the biocatalytic resolution of racemic epoxy-precursor (2-tert-butyl-2-[2-(4-chlorophenyl)ethyl] oxirane, rac-1a) by Escherichia coli/Rpeh whole cells expressed epoxide hydrolase from Rhodotorula paludigensis (RpEH), followed by a one-step chemocatalytic synthesis of (R)-tebuconazole. It was observed that (S)-1a was preferentially hydrolyzed by E. coli/Rpeh, whereas (R)-1a was retained with a specific activity of 103.8 U/g wet cells and a moderate enantiomeric ratio (E value) of 13.4, which was remarkably improved to 43.8 after optimizing the reaction conditions. Additionally, a gram-scale resolution of 200 mM rac-1a was performed using 150 mg/mL E. coli/Rpeh wet cells, resulting in the retention of (R)-1a in a 97.0% ees, a 42.5% yields, and a 40.5 g/L/d space-time yield. Subsequently, the synthesis of highly optical purity (R)-tebuconazole (>99% ee) was easily achieved through the chemocatalytic ring-opening of the epoxy-precursor (R)-1a with 1,2,4-triazole. To elucidate insight into the enantioselectivity, molecular docking simulations revealed that the unique L-shaped substrate-binding pocket of RpEH plays a crucial role in the enantioselective recognition of bulky 2,2-disubstituted oxirane 1a.

Effect of Different Carbon Sources on Antioxidant Properties of Exopolysaccharides Produced by Scleroderma areolatum (Agaricomycetes).

Five kinds of exopolysaccharides (EPS) were obtained by fermentation of Scleroderma areolatum Ehrenb. with sucrose, glucose, maltose, lactose, and fructose as carbon sources. Antioxidant abilities of the obtained EPSs were evaluated by inhibiting AAPH, HO·, and glutathione (GS·) induced oxidation of DNA and quenching 2,2'-azinobis (3-ethylbenzothiazoline-6-sulfonate) cationic radical (ABTS· and galvinoxyl radicals. The effects of carbon sources on the antioxidant properties of EPSs could be examined. The results showed that five EPSs can effectively inhibit radicals induced oxidation of DNA, and the thiobarbituric acid reactive substances (TBARS) percentages were 44.7%-80.8%, 52.3%-77.5%, and 44.7%-73.3% in inhibiting AAPH, HO·, and GS· induced oxidation of DNA, respectively. All five EPSs could scavenge ABTS· and galvinoxyh, and exhibit superior activity in scavenging free radicals. Antioxidant abilities of EPS with fructose as carbon source were highest among five EPS.

Circ_0001861 facilitates trophoblast cell proliferation, migration, invasion and epithelial-mesenchymal transition via the miR-296-5p/forkhead box protein 1 pathway in preeclampsia.

BACKGROUND: Preeclampsia (PE) is one of the leading causes of maternal mortality and placental trophoblastic disorders. Recent studies reported that circular RNAs (circRNAs) were involved in PE pathogenesis. However, the role of circ_0001861 in PE progression is largely unknown. METHODS: The RNA expression of circ_0001861, forkhead box protein 1 (FOXP1) and microRNA-296-5p (miR-296-5p) was detected by quantitative real-time polymerase chain reaction (qRT-PCR) assay. Western blot assay was performed to examine the protein levels of FOXP1 and epithelial-mesenchymal transition (EMT) markers. Cell viability, proliferation, migration and invasion were detected by cell counting kit-8, 5-ethynyl-2'-deoxyuridine, and transwell assays. Luciferase reporter assay, RNA pull-down assay, and RNA immunoprecipitation (RIP) assay were conducted to explore the interaction between miR-296-5p and circ_0001861 or FOXP1. RESULTS: Circ_0001861 and FOXP1 were downregulated but miR-296-5p was upregulated in PE placenta. Upregulation of circ_0001861 facilitated trophoblast cell proliferation, migration, invasion and EMT. Mechanistically, circ_0001861 sponged miR-296-5p to elevate FOXP1 expression, thus promoting trophoblast cell progression. CONCLUSION: The circ_0001861/miR-296-5p/FOXP1 axis plays a critical role in trophoblast cell proliferation, migration, invasion and EMT, which may provide a novel insight into developing potential therapeutic targets for PE.

Antibacterial metabolites from the beetle-associated fungus Penicillium chrysogenum.

The antibacterial secondary metabolites of the fungus Penicillium chrysogenum associated with the beetle Aspongopus chinensis were investigated through chromatographic fractionation methods of ethyl acetate extracts of the fungal cultures. Five compounds were isolated, and their structures were determined as emodin, 4-(methoxymethyl)benzoic acid, isoochracinic acid, secalonic acid D, and dicerandrol A using mass spectroscopy and nuclear magnetic resonance spectroscopic analyses. Emodin exhibited strong antimicrobial activity, especially against Staphylococcus aureus even when growing on cooked pork, with a minimal inhibitory concentration (MIC) of 6.3 µg/mL. Dimeric tetrahydroxanthones, such as secalonic acid D and dicerandrol A, also exhibited potent activity, with MIC values ranging from 9.5 to 28.5 µg/mL. In summary, P. chrysogenum was isolated as a symbiotic fungus of the beetle A. chinensis for the first time and this strain could generate antibacterial secondary metabolites, which could potently inhibit gram-positive bacteria growth in vitro.

Large-scale genomic and transcriptomic profiles of rice hybrids reveal a core mechanism underlying heterosis.

BACKGROUND: Heterosis is widely used in agriculture. However, its molecular mechanisms are still unclear in plants. Here, we develop, sequence, and record the phenotypes of 418 hybrids from crosses between two testers and 265 rice varieties from a mini-core collection. RESULTS: Phenotypic analysis shows that heterosis is dependent on genetic backgrounds and environments. By genome-wide association study of 418 hybrids and their parents, we find that nonadditive QTLs are the main genetic contributors to heterosis. We show that nonadditive QTLs are more sensitive to the genetic background and environment than additive ones. Further simulations and experimental analysis support a novel mechanism, homo-insufficiency under insufficient background (HoIIB), underlying heterosis. We propose heterosis in most cases is not due to heterozygote advantage but homozygote disadvantage under the insufficient genetic background. CONCLUSION: The HoIIB model elucidates that genetic background insufficiency is the intrinsic mechanism of background dependence, and also the core mechanism of nonadditive effects and heterosis. This model can explain most known hypotheses and phenomena about heterosis, and thus provides a novel theory for hybrid rice breeding in future.

Structure Characterization and Anti-Inflammatory Activity of Polysaccharides from Lingzhi or Reishi Medicinal Mushroom Ganoderma lucidum (Agaricomycetes) by Microwave-Assisted Freeze-Thaw Extraction.

A water-soluble polysaccharide (GLP-2) was isolated and purified from Ganoderma lucidum by the microwave-assisted freeze-thaw method. Microwave-assisted rapid thawing treatment can greatly improve the extraction yield of polysaccharides. The chemical structure of GLP-2 was analyzed with FT-IR, HPLC, GC-MS, and NMR spectrometry. It was proved that GLP-2 is mainly composed of ß-1,3-glucose and ß-1,6-glucose. The chain conformation of GLP-2 was analyzed by SEC-MALLS-RI, indicating that GLP-2 adopts semi-rigid chain conformation. Its molecular weight is 16.7 × 104, and its molecular size is about 61.2 nm. MTT assay indicated that GLP-2 was non-toxic to RAW 264.7 cells in vitro. The results of anti-inflammatory studies showed that GLP-2 can inhibit the production of NO, TNF-α, IL-1ß, and IL-6 in RAW 264.7 macrophage stimulated by lipopolysaccharide (LPS). The above data showed that the extraction method used in this study can obtain a high-yield polysaccharide with anti-inflammatory activity.

Novel kojic acid derivatives with anti-inflammatory effects from Aspergillus versicolor.

Two novel kojic acid derivatives, kojicones A and B (1 and 2), along with the precursors kojic acid (3) and (2R,4R)-4-hydroxy-5-methoxy-2,4-dimethyl-2- [(2R)-2-methylbutyryloxy]-5-cyclohexen-1,3-dione (4), were isolated from a fungal strain Aspergillus versicolor. Their structures and absolute configurations were accurately confirmed by HRESIMS data, NMR analysis, and electronic circular dichroism (ECD) calculations. Kojicones A and B were the first examples of kojic acid adducts with cyclohexen-1,3-dione possessing unprecedented tricycle skeletons. Compounds 1-3 were found to have inhibition on the NO production of murine RAW 264.7 cells. They can also reduce the mRNA expression of four cytokines (IL-6, IL-1ß, TNF-α, and iNOS) and promote the expression of IL-4 at 20 µM. Moreover, kojic acid (3) could treat the DSS (dextran sulfate sodium)-induced colitis on mice with the effectiveness similar to that of the positive control. The results suggested that kojic acid and its derivatives could be a promising anti-inflammatory source for the medicinal and cosmetic industry.

Effect of tween 40 and ethanol on the secretion, structure and antioxidant activities of exopolysaccharides from Inonotus rickii.

In this study, the effects of Tween 40 and ethanol supplementation on the secretion, structure and antioxidant activities of exopolysaccharide (EPS) from Inonotus rickii were investigated. It was observed that Tween 40 and ethanol displayed a stimulatory effect on EPS secretion. The EPSs obtained by the addition of Tween 40 (EPS-T), ethanol (EPS-E) and control (EPS-C) were purified by Sepharose CL-6B gel chromatography and molecular weights of EPS-T, EPS-E and EPS-C were estimated to be 22.1, 30.0, and 40.5 kDa, respectively. Monosaccharide composition analysis indicated that EPS-T, EPS-E and EPS-C were mainly composed of mannose and glucose. Furthermore, EPS-E exhibited better OH• and DPPH scavenging activities than those of EPS-C and EPS-T, which might be associated with its molecular characterization.

Effect of Carbon Source on Properties and Bioactivities of Exopolysaccharide Produced by Trametes ochracea (Agaricomycetes).

The effects of carbon source on properties and bioactivities of exopolysaccharide (EPS) produced by Trametes ochracea were investigated in this study. The results indicated that EPS production varied with five different carbon sources. After a fermentation period of 8 days, sucrose was the most suitable carbon source for biomass and EPS production. The predominant carbohydrate compositions in EPSs identified were glucose and mannose. The EPS fermented by sucrose has the highest glucose content. Then, FT-IR spectral analysis revealed prominent characteristic groups in EPSs. Each particular EPS possessed the specific bands at 808-809 cm-1 and 914-922 cm-1, indicating both α- and ß-configurations of the sugar units. Furthermore, thermogravimetric analysis (TGA) indicated the EPS with sucrose and glucose as carbon source showed different degradation behavior compared with the other three EPSs. The variation also affects antioxidant and antihyperlipemia activities investigated using hydroxyl and DPPH radical scavenging assay, and in hyperlipemia mice. Sucrose was the best carbon source from the viewpoint of OH and DPPH radical scavenging activities, and antihyperlipemia activity, probably due to the relatively high glucose content in EPS.

Synthesis of gold-silver nanoalloys under microwave-assisted irradiation by deposition of silver on gold nanoclusters/triple helix glucan and antifungal activity.

Polysaccharides are ideal green synthetic raw materials to improve the biocompatibility of metal nanoparticles. However, polysaccharides generally have weak reducibilities, being challenging supports for the direct preparation of Ag nanoparticles. In this work, gold nanoclusters were prepared using a triple helix glucan (Lentinan) via microwave-assisted synthesis and subsequently employed as seeds for the synthesis of a series of Ag-Au alloy nanoparticles (Ag-AuNPs). The results showed that gold nanoclusters can remarkably speed up the preparation of Ag-AuNPs without the addition of any other chemicals. The particle size of Ag-AuNPs increased at increasing Ag contents in the alloy. Results of UV-vis, transmission electron microscope (TEM) and inductively coupled plasma mass spectrometry (ICP-MS) suggested that Ag+ was quickly reduced to irregular silver nanoparticles (with gold nanoparticles as seeds), then gradually form more regular nano-alloys. Additionally, X-ray diffraction (XRD) and zeta potential results suggested that Ag-AuNPs could entrap the hydrophobic cavity of triple helix polysaccharides during the renaturation process. The nanocomposites exhibited good antifungal activity and low cytotoxicity to RAW264.7, Hela and LO2 cell lines in vitro.

Antioxidant coumarin and pyrone derivatives from the insect-associated fungus Aspergillus Versicolor.

Two new compounds, versicolones A and B (1 and 2), and three known pyrone derivatives (3-5) were isolated from the insect-associated fungus Aspergillus versicolor. Their structures were elucidated through a combination of HRESIMS and NMR spectroscopic analysis. Versicolone A (1) was revealed as a coumarin derivative with the rare 5-alkyl side chain substitution. Compound 5 exhibited significant antioxidant activity with EC50 value of 8.0 µM in the ABTS (2,2-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid) assay, which was more than 2-fold potency of the positive control trolox.

Antifungal Macrocyclic Trichothecenes from the Insect-Associated Fungus Myrothecium roridum.

Three new macrocyclic trichothecenes possessing rare 6'-ketal moieties, roridoxins A-C (1-3), and five known compounds (4-8) were isolated from the insect-associated fungus Myrothecium roridum. Their structures were confirmed by a combination of NMR and HRESIMS data, while their absolute configurations were unambiguously determined by single-crystal X-ray analysis and electronic circular dichroism experiments. Trichothecenes 1 and 3 showed potent antifungal activities against four strains of phytopathogenic fungi. In addition, 1, 3, 5, and 6 were found to significantly inhibit the cell growth of Candida albicans with minimal inhibitory concentration values from 8.8 to 18.5 µg/mL. Moreover, they were able to inhibit the biofilm formation of C. albicans better than the positive control.

Production, structural characterization, and antiproliferative activity of exopolysaccharide produced by Scleroderma areolatum Ehrenb with different carbon source.

The effects of different three carbon sources, that is, glucose, fructose, and sucrose, on production, molecular properties and antiproliferative activity of exopolysaccharide (EPS), were evaluated in the submerged culture of Scleroderma areolatum Ehrenb. Among carbon sources examined, the addition of sucrose maximizes the mycelia production, while fructose could maximize the EPS yield. Although the predominant carbohydrate compositions identified were gluconic acid and mannose, the monosaccharide composition of EPSs was also different significantly. FT-IR spectral analysis revealed there was no significant difference among the prominent characteristic groups in three EPSs. The molecular weight of EPSs was also affected by carbon source, being generally lower compared with that with glucose. However, all EPSs molecule existed as nearly globular shape form in aqueous solution. The variation of carbon sources also affected antiproliferative activity examined in vitro using cell proliferation assay. Fructose was optimal carbon source giving higher antiproliferative activity probably due to the relatively high contents of xylose in the EPS with low molecular weight.

Characterization and Antioxidant Activity of an Exopolysaccharide Produced by Rigidoporus microporus (Agaricomycetes).

In this investigation we developed an optimal fermentation medium to produce an exopolysaccharide (EPS) with antioxidant activity from Rigidoporus microporus. Lactose and tryptone were chosen as the optimal carbon and nitrogen sources, respectively, for EPS production, with a 6-day cultivation cycle. After removing proteins through the use of the Sevag method, one EPS fraction was purified from the culture filtrates by gel filtration chromatography on a Sepharose CL-6B column. The preliminary chemical structure of the EPS fraction was determined by Fourier transform infrared spectroscopy, gas chromatography-mass spectrometry, and nuclear magnetic resonance. The results indicated that the main structure of the EPS consisted of ß-glucopyranose and mannopyranose. Furthermore, conformational parameters such as molecular weight (Mw), intrinsic viscosity ([η]), mean-square radii of gyration (Rg), and hydrodynamic radius (Rh) of the EPS were characterized using a size exclusion chromatography-multiangle light scattering-refractive index viscometry method. It showed that the EPS was a kind of water-soluble polysaccharide with a moderate molecular weight (34.1 × 104) and a flexible, linear random coil chain structure. The antioxidant activity tests suggested that the EPS has great potential application as a natural antioxidant material in foods and medicines.

Molecular Characterization of Two Polysaccharides from Phellinus vaninii Ljup and their Cytotoxicity to Cancer Cell Lines.

BACKGROUND: Phellinus vaninii, a medicinal basidiomycete fungus, is often confused with Phellinus igniarius and Phellinus linteus. Polysaccharides extract from P. igniarius and P. linteus are reported to stimulate humoral immunity and inhibit tumor growth However, available literature reviewed no information on the relationship between bioactivities and structures of polysaccharides from the fruit body of P. vaninii. METHODS: Two water-soluble polysaccharides (PV-W, PV-B) were isolated and purified from fruiting bodies of P. vaninii by hot water and sodium hydroxide solution, respectively. The chemical structures of PV-W, PV-B were analyzed by FT-IR, GC-MS analysis and 13C NMR spectra. And, their molecular conformations were analyzed by viscosity method and SEC-MALLS-RI. Finally, their inhibition of cancer cells was investigated using MTT assay. RESULTS: The results illustrated that PV-W was a heteropolysaccharide, mainly composed of mannose, glucose, arabinose and galactose. PV-B was a ß-1, 3-D-glucan branched with ß-1, 6-D-glucose. The results of viscometry proved that PV-W and PV-B could be molecularly dispersed in water without aggregation. The results of SECMALLS- RI indicated that the two polysaccharides had the similar Mw but different molecular conformation. That is, PV-W existed as a stable globular shape, while PV-B presented a more expanded flexible random coils conformation. MTT assay indicated that PV-B showed higher inhibition effect on HepG2 and HeLa cells than PV-W in vitro. CONCLUSION: This work provided the important information of active components from P. vaninii and its potential applications in the food and medicine industry.

Effect of carbon source on production, characterization and bioactivity of exopolysaccharide produced by Phellinus vaninii Ljup.

The effect on different three carbon source (i.e. glucose, fructose and sucrose) on production, chemical characterization and antioxidant activity of exopolysaccharide (EPS) produced by Phellinus vaninii Ljup was investigated in this study. Amongst carbon sources examined, glucose and sucrose were favorable for the mycelia growth, while the maximum EPS yield was achieved when sucrose was employed. The predominant carbohydrate compositions in EPSs identified were gluconic acid, glucose, mannose and galactose acid. Then, FT-IR spectral analysis revealed prominent characteristic groups in EPSs. EPSs molecule exist as nearly globular shape form in aqueous solution. The variation also affects antioxidant activities by investigated by using hydroxyl and DPPH radical scavenging assay. Sucrose was best carbon source from the viewpoint of antioxidant activity due to the relatively high contents of galactose in the EPS with moderate molecular weight and polydispersity.

Sulfation of the Extracellular Polysaccharide Produced by the King Oyster Culinary-Medicinal Mushroom, Pleurotus eryngii (Agaricomycetes), and Its Antioxidant Properties In Vitro.

Extracellular polysaccharide from Pleurotus eryngii was sulfated; the optimum reaction conditions used pyridine as the reaction solvent, a temperature of 80°C, and a reaction time of 90 minutes. The structure and antioxidant activity of the sulfated and original polysaccharides (designated as SF-1 and Fr-1, respectively) were investigated. The main functional groups of polysaccharides were determined by Fourier transform infrared, and the chain conformation was determined by size-exclusion chromatography with laser light scattering and viscometry. Fourier transform infrared spectra indicated that the sulfated group was linked to the polymer. The molecular weight of SF-1 was much lighter than that of Fr-1, which suggested that degradation occurred during sulfation. The stable globular shape conformation of Fr-1 was changed to the random coil conformation of SF-1 in the aqueous solution. Moreover, the sulfated derivative SF-1 was found to have a better scavenging ability on hydroxyl radicals and DPPH free radicals than Fr-1. It seems that the chemical modification of P. eryngii polysaccharides by sulfation effectively enhances their antioxidant activity.

Effect of carbon source on production, characterization and bioactivity of exopolysaccharide produced by Phellinus vaninii Ljup

ABSTRACT The effect on different three carbon source (i.e. glucose, fructose and sucrose) on production, chemical characterization and antioxidant activity of exopolysaccharide (EPS) produced by Phellinus vaninii Ljup was investigated in this study. Amongst carbon sources examined, glucose and sucrose were favorable for the mycelia growth, while the maximum EPS yield was achieved when sucrose was employed. The predominant carbohydrate compositions in EPSs identified were gluconic acid, glucose, mannose and galactose acid. Then, FT-IR spectral analysis revealed prominent characteristic groups in EPSs. EPSs molecule exist as nearly globular shape form in aqueous solution. The variation also affects antioxidant activities by investigated by using hydroxyl and DPPH radical scavenging assay. Sucrose was best carbon source from the viewpoint of antioxidant activity due to the relatively high contents of galactose in the EPS with moderate molecular weight and polydispersity.

Construction of selenium nanoparticles/ß-glucan composites for enhancement of the antitumor activity.

We report on a green procedure for the stabilization of selenium nanoparticles (SeNPs) by a naturally occurring ß-glucan with triple helical conformation known as Lentinan (t-LNT) in water after denaturing into single chains (s-LNT) at 140 °C. The results demonstrated that the s-LNT can interact with SeNPs through Se-O-H interaction. Transmission electron microscopy (TEM), energy dispersive X-ray (EDX) spectra, UV/vis, X-ray diffraction (XRD) and dynamic light scattering (DLS) showed that s-LNT coated SeNPs to form a stable nano-composite Se/s-LNT, leading to good dispersion of SeNPs. Especially, the as-prepared Se/s-LNT composite in the solution could remain homogeneous and translucent for 30 days without any precipitates. Different size distribution of SeNPs was prepared by simply controlling the concentrations of selenite sodium and the corresponding reducing agent ascorbic acid. The size effect of SeNPs on anti-tumor activity was revealed that the SeNPs with more evenly particle size distribution show the higher anticancer activity.

Optimization, Purification, Characterization, and Antioxidant Activity of Exopolysaccharide Produced by the Northern Tooth Mushroom, Climacodon septentrionalis (Basidiomycota).

The optimization, purification, and characterization of exopolysaccharide (EPS) from Climacodon septentrionalis were investigated. The results showed that the optimal incubation time was 8 days for EPS production by C. septentrionalis; maltose and soy extract were the best carbon and nitrogen sources, respectively. One kind of EPS fraction was purified; it had a molecular weight of about 3.4 × 10(5) Da and mainly comprised glucose (98%). The main structure of EPS is α-glucopyranose. In addition, the EPS showed good antioxidant properties in vitro. The thermal stability of EPS also was investigated, and the results suggest that to maintain its bioactivity the processing temperature of EPS should not be more than 200°C. The structural characteristics of EPS, such as molecular weight, functional groups, monosaccharide constituents, and configuration of the glycosidic bond give EPS great potential for application as a natural antioxidant material in health, food, and therapeutics.