Nortriterpene glycosides of the sarasinoside class from the sponge Lipastrotethya sp.

Five new nortriterpene glycosides, along with eight known compounds of the sarasinoside class, were isolated from the tropical sponge Lipastrotethya sp. collected from Chuuk, Micronesia. The structures of these new compounds, designated as sarasinosides N-R (9-13), were determined by combined spectroscopic and chemical methods. The aglycone portions of 10-13 were found to be unprecedented among nortriterpeneoids on the basis of extensive NMR analyses. Several of these compounds exhibited cytotoxicity against A549 and K562 cell lines as well as weak inhibitory activity against Na(+)/K(+)-ATPase.