Ten new (-) and nine known (-) austocystins, along with four known anthraquinones (-), were isolated from the culture of NRRL 5856 by bioactivity-guided fractionation. The structures of the new compounds were elucidated by spectroscopic data analysis, X-ray crystallographic study, the modified Mosher's method, [Rh(OCOCF3)]-induced ECD spectral analysis, and comparison of the experimental ECD spectra with those of the similar analogues. Compounds - represent the first examples of austocystins with a C-4' oxygenated substitution.
View Article and Find Full Text PDFEight unreported andrastin-type meroterpenoids, namely peniandrastins A-H (1-8), along with six known analogues (9-14), were isolated from the fermentation of a soil-derived fungus Penicillium sp.sb62. Their structures with absolute configurations were elucidated by detailed analyses of the spectroscopic data and single-crystal X-ray diffraction.
View Article and Find Full Text PDFFourteen new [11]-chaetoglobosins (1-14), along with two known congeners, cytochalasins X and Y (15 and 16), were isolated from the cultures of an endophytic fungus Pseudeurotium bakeri P1-1-1. Their structures incorporating absolute configurations were elucidated based on the comprehensive analyses of one- and two-dimensional NMR data, HRESIMS spectrometry, chemical methods, and single-crystal X-ray diffraction analysis (Cu Kα). All isolates were evaluated for their cytotoxic activities and chaetopseudeurin M (1) displayed significant cytotoxic effects against seven human cancer cell lines, with IC values ranging from 5.
View Article and Find Full Text PDFSeven undescribed cytochalasins, multirostratins K - Q (2: -8: ), together with one known analogue, cytochalasin Z3 (1: ), were isolated from the culture of XJ-2-1, an endophytic fungus obtained from the root of . Their structures with absolute configurations were determined by 1D and 2D NMR, high-resolution electrospray ionization mass spectrometry (HRESIMS), electronic circular dichroism (ECD), single-crystal X-ray crystallography, and chemical methods. The structure of ascochalasin was revised from to by detailed analysis of the NMR data and by comparison with the data for 7: .
View Article and Find Full Text PDFThree pairs of new heterodimeric polyketide enantiomers, (±)-usphenethylones A-C (1-3), were isolated from the culture extract of 3.3904. Compounds 1-3 present two heterodimerization patterns by a phenylethyl unit connected to an α-pyrone moiety, of which usphenethylones A-B (1-2) feature a 2,6,18-trioxa-tetracyclo-[8.
View Article and Find Full Text PDFAspersteroid A (), a highly rearranged 1(10 → 6)--18,22-cyclosterol, together with two new 18,22-cyclosterols ( and ), was isolated from the culture extract of NRRL 275. Their structures were determined by spectroscopic analysis, X-ray diffraction, modified Mosher's method, and Rh(OCOCF)-induced electronic circular dichroism experiments. Compound represents a new carbon skeleton with an uncommon 6/6/6/5/5 ring system, which is presumably biosynthesized from A-ring scission, double 1,2-shifts, and C-18/C-22 cyclization.
View Article and Find Full Text PDFPodomycins A-L (1-12), 12 undescribed hypothemycin-type resorcylic acid lactones (RALs), were characterized from Podospora sp. G214, an endophyte harbored in the roots of Sanguisorba officinalis L. Their structures were addressed by spectroscopic data, X-ray crystallography, the modified Mosher's method, together with Mo(OAc)- and Rh(OCOCF)-induced electronic circular dichroism (ICD) experiments.
View Article and Find Full Text PDFTen novel (, , , , , , , , , and ) furancarboxylic acids including four pairs of epimers (, ; , ; , ; , ), together with seven known analogues (, , , , , , and ), were isolated from the fermentation of the soil-derived fungus sp. sb62. Their structures were established on the basis of spectroscopic data analysis, and the absolute configurations were determined by time-dependent density functional theory electronic circular dichroism calculations, comparison of the specific optical rotation values, and modified Mosher's method.
View Article and Find Full Text PDFFour novel rearranged cytochalasans (-) were isolated from an endophytic fungus P2-2-2. Pchaeglobolactone A () possessed an unprecedented 13-aza-21-oxa-tetracyclo-[10.6.
View Article and Find Full Text PDFErgocytochalasin A (1), an unprecedented merocytochalasan formed via Diels-Alder cycloaddition of a cytochalasin with an ergosterol, was isolated from an endophytic fungus Phoma multirostrata XJ-2-1. Compound 1 possessed a unique 5/6/14/6/5/6/6/6 fused octacyclic ring system and its structure was established by detailed NMR and HRESIMS spectroscopic analyses. The absolute configuration of 1 was determined by single-crystal X-ray diffraction.
View Article and Find Full Text PDFTwelve new resorcylic acid lactones (RALs) including three new 16-membered RALs (, and ), eight new 14-membered RALs (-), and one new 12-membered RAL (), along with five known 14-membered RALs (-), were identified from the fermentation of the soil-derived fungus sp. sb65. Their structures were established by detailed analyses of 1D and 2D NMR, HRESIMS, and X-ray diffraction crystallography.
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