Clavuridins A and B, two new trinor-guaiane sesquiterpenes isolated from the Xisha soft coral Clavularia viridis

In the present study, two new trinor-guaiane sesquiterpenes, named clavuridins B ( 1 ), and A ( 2 ), along with three known sesquiterpenes ( 3 - 5 ), were isolated from the Xisha soft coral Clavularia viridis. Their structures and absolute configurations were determined on the basis of spectroscopic analysis, X-ray diffraction analysis with Cu Kα radiation and by comparison with related model compounds. Compounds 1 and 3 - 5 were evaluated for their cytotoxic activity.