Two new hirsutane-type sesquiterpenoids chondrosterins N and O from the marine fungus Chondrostereum sp.

The marine fungus Chondrostereum sp. was collected from a soft coral Sarcophyton tortuosum from the South China Sea. This fungus was cultured in glucose-peptone-yeast (GPY) medium and the culture broth was extracted with EtOAc. By the method of 1H NMR pre-screening and tracing the diagnostic proton signals of the methyl groups, two new hirsutane-type sesquiterpenoids, chondrosterins N and O (1 and 2) were isolated from the metabolite extracts. Their structures were elucidated on the basis of MS, 1D and 2D NMR data.