Five novel norcembranoids from Sinularia leptoclados and S. Parva

Three new norcembrane-based diterpenoids, leptocladolides A (), B () and C (), along with five known metabolites , have been isolated from the dichloromethane extract of a Taiwanese soft coral Sinularia leptoclados. Furthermore, a chemical investigation on the dichloromethane extract of S. parva has resulted in the isolation of two new related isomers, 1-epi-leptocladolide A () and 7E-leptocladolide A (), in addition to and . The structures of new metabolites were elucidated on the basis of extensive spectroscopic analyses and their relative stereochemistries were determined by NOESY experiments. The new metabolites and have been shown to exhibit significant cytotoxic activity against KB and Hepa59T/VGH cancer cell lines.