New cytotoxic constituents from the Formosan soft corals Clavularia viridis and Clavularia violacea.

Three new cytotoxic prostanoids, claviridenone E-G (1-3), and three new cytotoxic steroids, stoloniferone E-G (4-6), were isolated from the methylene chloride solubles of the Formosan soft coral Clavulariaviridis. A cytotoxic cembranoid, claviolide (7), was isolated from the methylene chloride solubles of the Formosan soft coral Clavularia violacea. The structures were elucidated by 1D and 2D NMR spectral analysis, and their cytotoxicity against selected cancer cells was measured in vitro.