Altohyrtins B and C and 5-desacetylaltohyrtin A, potent cytotoxic macrolide congeners of altohyrtin A, from the okinawan marine sponge Hyrtios altum.

Abstract

Following the characterization of altohyrtin A (1), altohyrtins B (2) and C (3) and 5-desacetylaltohyrtin A (4) have been isolated from the Okinawan marine sponge Hyrtios altum and their plane structures and parts of their relative configurations elucidated. Three congeneric macrolides (2, 3, and 4) exhibit extremely potent cytotoxicities similar to those of 1 against KB cells with IC50 values of 0.02, 0.4, and 0.3 ng/ml, respectively.