Flabelliferins A and B, Sesterterpenoids from the South Pacific Sponge <i>Carteriospongia flabellifera</i>

Abstract

Two new sesterterpenoids named flabelliferins A (<b>1</b>) and B (<b>2</b>) were isolated from the lipophilic extract of the sponge <i>Cateriospongia flabellifera,</i> collected in the South Pacific near Vanuatu. The structure and absolute configuration of these two compounds were assigned by a combination of one- and two-dimensional NMR spectroscopy and by Mosher’s ester analysis. Flabelliferin A (<b>1</b>) has a rare 25-homocheilanthane carbon skeleton, while flabelliferin B (<b>2</b>) is a 24-nor-25-homoscalarane sesterterpenoid