A new cytotoxic calyculinamide derivative, geometricin A, from the Australian sponge Luffariella geometrica.

Geometricin A (1), together with the known compounds (7E,12E,18S,20Z)-variabilin (2), clathryimine A (3), tryptophol (4), and L-tryptophan, has been isolated from the methanol extract of the Australian sponge Luffariella geometrica. The structure of the new compound geometricin A (1) was elucidated by employing spectroscopic techniques (NMR, MS, UV, and IR) and by comparison of its NMR data with those of the calyculins and calyculinamides. Geometricin A (1) was found to be moderately cytotoxic toward the tumor cell lines HM02 and HEPG2 with GI50's of 1.7 and 2.8 microg/mL, respectively, and to have antialgal activity (growth inhibition zone 5 mm at the 50 microg level).