In Vitro Anticancer and Proapoptotic Activities of Steroidal Glycosides from the Starfish .

New marine glycoconjugates-the steroidal glycosides designated as anthenosides V⁻X (⁻)-and the seven previously known anthenosides E (), G (), J (), K (), S1 (), S4 (), and S6 () were isolated from the extract of the tropical starfish . The structures of ⁻ were elucidated by extensive NMR and ESIMS techniques. Glycoside contains a rare 5α-cholest-8(14)-ene-3α,7β,16α-hydroxysteroidal nucleus. Compounds and were isolated as inseparable mixtures of epimers. All investigated compounds (⁻) at nontoxic concentrations inhibited colony formation of human melanoma RPMI-7951, breast cancer T-47D, and colorectal carcinoma HT-29 cells to a variable degree. The mixture of and possessed significant anticancer activity and induced apoptosis of HT-29 cells. The molecular mechanism of the proapoptotic action of this mixture was shown to be associated with the regulation of anti- and proapoptotic protein expression followed by the activation of initiator and effector caspases.