Five new polyacetylenes from a sponge of the genus petrosia

Petrocortynes D-H, novel C46 polyacetylenes, were isolated from a sponge of the genus Petrosia collected from Keomun Island, Korea. Petrocortyne D (2) is a 4,5-dihydro derivative of a diastereomer of petrocortyne A (1), and petrocortynes E-H (3-6) possess an additional allylic-hydroxyl group. The structures of these compounds were determined by combined chemical and spectral methods, and absolute configurations of most of the asymmetric carbon centers were determined by the modified Mosher's method. Limitations on the application of Mosher's method to allylic alcohols is discussed. Petrocortynes D-H exhibited moderate cytotoxicity and inhibitory activity against PLA2.