Neolemnane-type sesquiterpenoids from a formosan soft coral Paralemnalia thyrsoides

Six new sesquiterpenoids, paralemnolins D-I (1-6), have been isolated from the EtOAc extract of the soft coral Paralemnalia thyrsoides. The structures of these metabolites were determined by extensive spectroscopic analysis and by comparison of their spectral data with those of related metabolites. The absolute stereochemistry of these metabolites was established by application of the Mosher's method on 1 and on the basis of the absolute structures of other related compounds previously isolated from the soft corals of the genera Paralemnalia and Lemnalia. Cytotoxicity of these metabolites toward a limited panel of cancer cell lines also is reported.