By the method of H NMR prescreening and tracing the diagnostic proton signals of the methyl groups, three additional new triquinane-type sesquiterpenoids - chondrosterins K-M (1-3) and the known sesquiterpenoid anhydroarthrosporone (4) - were isolated from the marine fungus Chondrostereum sp. Their structures were elucidated on the basis of MS, 1D, and 2D NMR data. Chondrosterin K is a rare hirsutane sesquiterpenoid, in which a methyl group was migrated from C-2 to C-6 and has a double bond between C-2 and C-3. Compounds 1-3 showed significant cytotoxicities against various cancer cell lines in vitro.
Huang, L., Lan, W. J., Deng, R., Feng, G. K., Xu, Q. Y., Hu, Z. Y., … Li, H. J. (2016). Additional New cytotoxic triquinane-type sesquiterpenoids chondrosterins K-M from the marine fungus chondrostereum sp. Marine Drugs, 14(9). https://doi.org/10.3390/md14090157