Nardosinane Sesquiterpenoids from the Formosan Soft Coral Lemnalia flava

Four new nardosinane-type sesquiterpenoids, flavalins A−D (1−4), have been isolated from the Formosan soft coral Lemnalia flava. The structures of the new metabolites were determined by extensive spectroscopic analysis, and the structure of 2 was confirmed by X-ray diffraction analysis. A plausible biosynthetic pathway to 1 and 2 is proposed. Compound 1 was found to display dose-dependent inhibition of iNOS protein expression, and 1 and 2 were shown to possess significant neuroprotective activity.