New polyhydroxylated sterols from Palythoa tuberculosa and their apoptotic activity in cancer cells.

The chemical study on the total extract of the zoanthid Palythoa tuberculosa, collected from the Red Sea, resulted in the isolation of seven polyhydroxylated sterols (1-7), six of which, palysterols A-F (2-7), are new. Their chemical structures were elucidated on the basis of extensive analysis of their 1-, 2D NMR and MS spectroscopic data. This is the first chemical investigation on the species collected from Red Sea.

Bioactive terpenoids from the Red Sea soft coral Sinularia polydactyla.

Chemical investigation of an ethyl acetate soluble fraction of Sinularia polydactyla (Ehrenberg) led to the isolation of three known terpenoides, two of them sterols, 24-methylcholestane-3β,5α,6β,25-tetrol 25-monoacetate (1), 24-methylcholestane-5-en-3β,25-diol (2), in addition to a cembranoid diterpene, durumolide C (3), for the first time. The cytotoxicity and antimicrobial activities of the ethyl acetate extract and the isolated compounds 1-3 were evaluated in vitro. Durumolide C (3) showed selective cytotoxicity against HepG2 (IC50 1.