Chemical Constituents Of Two Endophytes Derived From Semi-mangrove Plant Hibiscus Tiliaceus

B0Culture conditions have a major impact on the growth and production of microbial metabolites. Our prior chemical study of the endophytic fungal strain Eurotium rubrum G2, which was obtained from the semi-mangrove plant Hibiscus tiliaceus, have afforded a variety of biologically active metabolites. To identify more active components, this fungus was refermented using the other fermentation culture. Meanwhile, another endophytic fungal strain Penicillium commune G2M, which was also obtained from Hibiscus tiliaceus, was selected and inoculated in sterilized solid medium for the investigation of its secondary metabolites. Some of the isolated compounds were evaluated for their bioactivities.The compounds were isolated by repeated column chromatography (CC) on silica gel, RP-18, and Sephadex LH-20, as well as by preparative thin layer chromatography (prep-TLC) and recrystallization. The structures of the isolated compounds were elucidated by means of spectroscopic methods including IR, UV, MS, 1D-NMR and 2D-NMR, as well as by comparison with authentic standards or with literature reports. Chemical investigation of Eurotium rubrum G2 afforded 32 compounds (2 were found to be new structures) including 1 benzaldehyde derivative (GH30), 11 anthraquinone derivatives (GH1~ GH11), 18 dioxopiperazine alkaloids (GH12~GH2), 1 triterpene (GH31), and 1 cholesterol (GH32). In addition, 14 compounds (with one new structure) were isolated and structurally elucidated from the extract of Penicillium commune G2M. Among them, 2 were multi-substituted benzenoid derivatives (PC5, PC 6), 2 were indole alkaloids (PC3, PC 4), 3 were nucleosides (PC8~ PC10), 4 were steroids (PC11~ PC14) and 3 were other types (PC1, PC2, PC7).Some of the purified compounds were evaluated for their cytotoxic activities, antibacterial and antifungal activities. Nine compounds displayed cytotoxic activities against 7 tumor cell lines. Among them, GH24 showed cytotoxic activity against human hepatoma cell line SMMC-7721 (IC50 of 11μg/mL). GH30 displayed cytotoxic activities against human cholangiocarcinoma cell sw1990 and human prostate cancer cell Du145 (IC50 of 10, 15μg/mL, respectively). The new compound GH11 exhibited weak inhibitory activity against E. coli.