Dactylolide, a new cytotoxic macrolide from the Vanuatu sponge Dactylospongia sp.

Dactylolide (1), a new cytotoxic 20-membered macrolide, was isolated from a marine sponge of the genus Dactylospongia collected off the coast of the Vanuatu islands. It co-occurred with other known bioactive macrolides: latrunculin A (2), laulimalide (3), isolaulimalide (4) and with the anthelminthic mycothiazole (5). The structure of 1, which is a minor metabolite, was elucidated by spectroscopy (mainly by 1D/2D NMR and MS techniques). It showed cytotoxic activity against the L1210 and SK-OV-3 tumor cell lines (63% and 40% inhibition at 3.2 mug/mL).