Petrocortynes and petrosiacetylenes, novel polyacetylenes from a sponge of the genus Petrosia

Petrocortynes A-C (1-3) and petrosiacetylenes A-D (4-7), novel long-chain polyacetylenes and related metabolites have been isolated from a sponge of the genus Petrosia. Compounds 1 and 2 are C-46 linear tetraacetylenes structurally related to petroformynes while 3 possesses an unusual gamma-pyrone ring formed by an oxidative cyclization of a diacetylenic carbinol functionality. Compounds 4-7 are highly symmetric C-30 linear polyacetylenes in that 6 and 7 were isolated as unseparable mixtures of diastereomers. The structures of these compounds have been elucidated by combined chemical and spectral methods. Absolute stereochemistry has been determined by the modified Mosher's method. These compounds exhibited significant brine-shrimp lethality, RNA-cleaving activity, and/or moderate inhibitory activity against PLA(2) and Na+/K+ ATPase. (C) 1997 Elsevier Science Ltd. All rights reserved.