[Secondary metabolites from Rhododendron molle endophyte Penicillium sp. RM and their inhibitory effects on tumor...

This study investigated the secondary metabolites of the endophytic fungus Penicillium sp. RM isolated from the toxic plant Rhododendron molle. Ten compounds were isolated and purified from the ethyl acetate extract of the fungal fermentation broth by silica gel column chromatography, gel column chromatography, and semi-preparative HPLC. The structures of these compounds were elucidated by comprehensive spectroscopic analyses, including NMR, MS, UV, IR, and CD. The identified compounds were as follows: penicidienone A(1), diversonol(2), alternariol(3), alternariol 9-methyl ether(4), methylated dechloromonilicin(5), norliquexantona(6), alternethanoxin A(7), α-diversonolic ester(8),(±)-asperlone A(9), and verruculotoxin(10). Compound 1 was identified as a new cyclopentenone derivative. Compound 9 showed inhibitory activity against the proliferation of HepG2(IC_(50)=9.7 μmol·L~(-1)), HGC27(IC_(50)=9.3 μmol·L~(-1)), and U251(IC_(50)=8.4 μmol·L~(-1)) cell lines.