20-nor-Isopimarane and isopimarane diterpenoids produced by Aspergillus sp. WT03.

Five new uncommon 20-nor-isopimarane diterpenoids, aspewentins N-R (1-5), and three related known congeners (6-8), along with an isopimarane diterpenoid, sphaeropsidin C (9), were isolated from a Coptis chinensis Franch. rhizosphere soil-derived fungal strain, Aspergillus sp. WT03. The structures of compounds 1-9 were characterized based on the comprehensive analysis of the spectroscopic data, and their absolute configurations were elucidated by single crystal X-ray diffraction and time-dependent density functional theory (TDDFT)-ECD calculations. Compounds 1-5 represent rare examples of 20-nor-isopimarane analogues featuring a 1,2,3,4-tetrahydronaphthalene and 3,4-dihydronaphthalen-1(2H)-one moiety. The biosynthetic pathway of these diterpenoids was also proposed. Additionally, compounds 1, 3 and 4 showed moderate cytotoxic activity against MCF-7, A549 and HT-29 cell lines.

New curtachalasin from the Xylaria sp. DO 1801.

One new cytochalasin, named curtachalasin Q (1), together with 8 known cytochalasins were isolated from the ethyl acetate extract of the Xylaria sp. DO1801. The structure of the new compound was elucidated on the basis of IR, UV, HR-ESI-MS, NMR spectra and X-ray diffraction. Compound 1 and 2 were not cytotoxic (IC50>50uM) against four tumour cell lines (SW-1990, ASPC-1, HepG2 and Hep3B).