Antiparasitic Ovalicin Derivatives from Pseudallescheria boydii,a Mutualistic Fungus of French Guiana Termites

Social insects are in mutualism with microorganisms, contributing to their resistance against infectious diseases. The fungus Pseudallescheria boydii SNB-CN85 isolated from termites produces ovalicin derivatives resulting from the esterification of the less hindered site of the ovalicin epoxide by long-chain fatty acids. Their structures were elucidated using spectroscopic analysis and semisynthesis from ovalicin. For ovalicin, these compounds displayed antiprotozoal activities against Plasmodium falciparum and Trypanosoma brucei, with IC₅₀ values of 19.8 and 1.1 µM, respectively, for the most active compound, i.e., ovalicin linoleate. In parallel, metabolomic profiling of a collection of P. boydii strains associated with termites made it possible to highlight this class of compounds together with tyroscherin derivatives in all strains. Finally, the complete genome of P. boydii strains was obtained by sequencing, and the cluster of potential ovalicin and ovalicin biosynthesis genes was annotated. Through these metabolomic and genomic analyses, a new ovalicin derivative named boyden C, in which the 6-membered ring of ovalicin was opened by oxidative cleavage, was isolated and structurally characterized.     

Two new polyhydroxysterols produced by Fusarium solani,an endophytic fungus from Chloranthus multistachys

A highly antagonistic endophytic fungus, designated strain CL39, was originated from the leaves of Chloranthus multistachys collected in Wulong of Chongqing municipality of China in November 2015. The strain was identified as Fusarium solani based on morphological characteristics, 5.8S gene and internal transcribed spacer sequence analysis. Two new compounds, 2β, 9α-dihydroxy-5α-methoxyergosta-7, 22-diene (1), 2β, 6β-dihydroxy-5α-methoxyergosta-7, 22-diene (2) have been isolated from the culture broth of the strain. Structures of the new compounds were elucidated by detailed analysis of their spectroscopic data aided by the comparison with reported data of related derivatives, and found to belong to the polyhydroxylated steroids with a hydroxyl at C-2 instead of C-3, a rare structure among the steroids. The extract of this strain and all isolated compounds were evaluated for their antagonistic activities.     

New analogues of brefeldin A from sediment-derived fungus Penicillium sp. DT-F29

Four new analogues of brefeldin A named 7, 7-dimethoxybrefeldin C (3), 6β-hydroxybrefeldin C (4), 4-epi-15-epi-brefeldin A (5), 4-epi-8α-hydroxy-15-epi-brefeldin C (6), together with four known analogues (1, 7?9) were isolated from a fermentation of the sediment-derived fungus Penicillium sp. DT-F29. The structures of these compounds were elucidated on the basis of extensive spectroscopic and chemical methods. In the bioactivity assays, only compounds 1 and 8 showed significant inhibitory activities against human lung adenocarcinoma cell. In addition, compound 1 was first reported for the potent ability to reactivate latent HIV with EC₅₀ value of 0.03 μM.     

1H and 13C NMR assignments for 6-demethylvermistatin and two penicillide derivatives from the mangrove fungus Guignardia sp. (No. 4382) from the South China Sea

One new compound 6-demethylvermistatin (1), together with two known compounds, the penicillide derivatives (2) and (3) were isolated from the mangrove fungus Guignardia sp. No. 4382 obtained from the South China Sea. Their structures were assigned using high-resolution electron ionization mass spectrometry(HREIMS), (1)H and (13)C NMR spectra, DEPT, and by 2D COSY, HMQC, and HMBC experiments. The absolute configuration of 1 was established by comparison of its CD with that of vermistatin.     

Blennolide derivatives from the soil-derived fungus Trichoderma asperellum PSU-PSF14

Three new blennolide derivatives, blennolides L-N (1–3), together with five known metabolites were isolated from the soil-derived fungus Trichoderma asperellum PSU-PSF14. Their structures were determined by analysis of spectroscopic data. Their relative configurations were determined by analysis of NOEDIFF data and confirmed by X-ray crystallography for compound 1 whereas the absolute configurations were established by means of experimental and calculated TDDFT ECD data. Compound 1 displayed antifungal activity against Cryptococcus neoformans ATCC90112 and ATCC90113 flucytosine-resistant with the MIC values of 128 and 64?μg/mL, respectively, and was inactive against noncancerous Vero cell lines.     

Withanolide production by fungal endophyte isolated from Withania somnifera

Withanolides, the secondary metabolite from Withania species is used in Ayurvedic medicine and now proved to have potential use in treating cardiovascular, Alzheimer’s disease, etc. Its production in plants varies between genotypes with very low yield. For improved industrial commercialisation, there is a need to increase its production. Endophytic fungi are symbiotically associated with plants and can synthesise the same bioactive compounds and natural products as their host plant. There are no reports available on withanolide-producing (endophytic) fungi. The present study identified an endophytic fungus (Taleromyces pinophilus) from leaves of Withania somnifera which produces withanolides in the medium. The structure of withanolide was confirmed by ¹H NMR, LC-MS analyses and quantified by HPLC analysis. The fungus produces high amount of withanolide when compared to leaf and root of W. somnifera. The fungus can be exploited to produce the withanolide to meet its demand.     

One new cytochalasin metabolite isolated from a mangrove-derived fungus Daldinia eschscholtzii HJ001

One new cytochalasin metabolite [11]-cytochalasa-5(6),13-diene-1,21-dione-7,18-dihydroxy-16,18-dimethyl-10-phenyl-(7S*,13E,16S*,18R*) (1), together with three known compounds (2–4) were obtained from the EtOAc extract of the endophytic fungus Daldinia eschscholtzii HJ001 isolated from the mangrove Brguiera sexangula var. rhynchopetala collected in the South China Sea. Their structures were elucidated by the detailed analysis of comprehensive spectroscopic data. Compounds 1 and 2 were evaluated for their antibacterial and cytotoxic activities.     

Three new aspochalasin derivatives from the marine-derived fungus Spicaria elegans

<正>Three new aspochalsins(R-T)(1-3) were isolated from the marine-derived fungus Spicaria elegans.Their structures were elucidated on the basis of comprehensive spectral analysis including 1D and 2D NMR techniques,and HR-ESI-MS.     

Prenylated indole alkaloids from the marine-derived fungus Paecilomyces variotii

Two new prenylated indole alkaloids, namely, dihydrocarneamide A (1) and iso-notoamide B (2), were isolated from the marine-derived endophytic fungus Paecilomyces variotii EN-291. The structures of these metabolites were determined based on comprehensive spectral analysis, together with chiral HPLC analysis of the acidic hydrolysates. Unlike other prenylated indole alkaloids such as asperparalines, notoamides, and versicolamides, compounds 1 and 2 are the rare examples of C-5 prenylation, forming the fused dimethyldihydropyran ring at C-5 and C-6 of the indole ring. The cytotoxic activity of the isolated compounds was evaluated.     

Benzopyranone,benzophenone, and xanthone derivatives from the soil fungus Penicillium citrinum PSU-RSPG95

Two new benzopyranones, named coniochaetones E (1) and F (2), one new xanthone, penicillone C (3), and one new benzophenone, penicillanone (4), are isolated from the soil fungus Penicillium citrinum PSU-RSPG95, together with ten known compounds. Their structures are identified on the basis of spectroscopic data. The isolated compounds are evaluated for their cytotoxic activity.