A new alpha,beta,gamma,delta-unsaturated carboxylic acid and three new cyclic peroxides from the marine sponge, Monotria japonica, which selectively lyse starfish oocytes without affecting nuclear morphology.

The marine sponge Monotria japonica contains cytolytic constituents, which have been fractionated to a new alpha,beta,gamma,delta-unsaturated carboxylic acid designated monotriajaponide A (1) and three new cyclic peroxides designated monotriajaponides B (2), C (3), and D (4), in addition to a known peroxide (5) and a known alpha,beta-unsaturated ester (6). The structures were determined on the basis of spectroscopic data. Compounds 1-5 lysed immature starfish (Asterina pectinifera) oocytes without affecting nuclear morphology at the minimum effective concentrations of 50, 6.3, 6.3, 6.3, and 13 microg/mL, respectively. On the other hand, compound 6, at the minimum effective concentration of 25 microg/mL, lysed both oocyte's plasma membrane and the nuclear envelope.