Triterpene Galactosides of the Pouoside Class and Corresponding Aglycones from the Sponge Lipastrotethya sp.

Nine new triterpene galactosides and aglycones, along with three known compounds from the rare pouoside class, were isolated from the tropical sponge Lipastrotethya sp. collected from Micronesia. The structures of these new compounds were determined by combined spectroscopic methods and designated as pouosides F-I (4, 8, 10, and 12) and pouogenins A-E (5-7, 9, and 11). The absolute configurations of the asymmetric centers and the cyclohexenone moiety, which had been previously undetermined, were assigned by NOESY analyses and Mosher's methods. Several of these compounds exhibited weak cytotoxicity against the K562 cell line.