Alertenone, a dimer of suberosenone from Alertigorgia sp.

Bioassay-guided fractionation of organic extracts of the gorgonian Alertigo rgia sp. has yielded the previously known suberosenone (1), a cytotoxic tri cyclic sesquiterpene of the quadrone class, and alertenone (2), a dimer of suberosenone. The structure of 2 was determined by spectral analysis; the 1 D TOCSY experiment was particularly useful in the structure elucidation. Co mparison of the in vitro cytotoxicity of alertenone and suberosenone reveal ed that the dimeric alertenone was devoid of cytotoxicity below 35 mu g/mL. In a hollow-fiber assay model of in vivo activity, suberosenone exhibited some growth inhibition of two of six tumor cell lines tested.