ISOMETACHROMIN, A NEW CYTOTOXIC SESQUITERPENOID FROM A DEEP-WATER SPONGE OF THE FAMILY SPONGIIDAE

Isometachromin (1), a new sesquiterpene-quinone that is related structurally to metachromin C (2), and the known compounds ilimaquinone (3) and and 5-epi-ilimaquinone (4), were isolated from a deep water sponge in the family Spongiidae; the structure of isometachromin was elucidated by spectral methods. Isometachromin exhibits in vitro cytotoxicity against the human lung cancer cell line A 549 (IC50 = 2.6 mug/ml), but not against P 388 murine leukemia (IC50 greater-than-or-equal-to 10 mug/ml) and also exhibits antimicrobial activity.