BIOACTIVE ISOQUINOLINE QUINONE FROM AN UNDESCRIBED PHILIPPINE MARINE SPONGE OF THE GENUS XESTOSPONGIA

An undescribed Philippine marine sponge of the genus Xestospongia affo rded four isoquinoline quinones: the new N-ethylene methyl ketone deri vative of renierone (1), as well as the known compounds methyl-7-metho xy-5,8-dihydroisoquinoline-5,8-dione (2), renierone (3), and mimosamyc in (4). Compound 2 exhibited insecticidal activity toward neonate larv ae of the polyphagous pest insect Spodoptera littoralis (EC(50) of 35 ppm and LC(50) of 521 ppm) when incorporated into artificial diet. Com pounds 1 and 3 were only weakly active toward S. littoralis, while com pound 4 was found to be inactive. All four isolated compounds were act ive against the Gram-positive bacteria Bacillus subtilis and Staphyloc coccus aureus. Compound 4 was also active against the fungus Cladospor ium cucumerinum.