The Indo-Pacific marine sponge Ircinia ramosa has been found to contain two powerful (GI50 from 0.001 to <0.0001 microg/mL) murine and human cancer cell growth inhibitors. Both were isolated (10(-3)-10(-4)% yields) by cancer cell line bioassay-guided techniques and named irciniastatins A (1) and B (2). Structural elucidation by a combination of spectral analyses, primarily high resolution mass and 2D-NMR (principally APT, HMQC, HMBC, and ROESY) spectroscopy, revealed the unusual structures 1 and 2.

As an extension of structure/activity investigations of resveratrol (1), phenstatin (2c), and the cancer antiangiogenesis drug sodium combretastatin A-4 phosphate (2b), syntheses of certain related stilbenes (14) and benzophenones (16) were undertaken. The trimethyl ether derivative of (Z)-resveratrol (4a) exhibited the strongest activity (GI(50) = 0.01-0.001 microg/mL) against a minipanel of human cancer cell lines. A monodemethylated derivative (14c) was converted to prodrug 14n (sodium resverastatin phosphate) for further biological evaluation. The antitubulin and antimicrobial activities of selected compounds were also evaluated.

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