NOVEL BIOACTIVE STYRYL-LACTONES - GONIOFUFURONE, GONIOPYPYRONE, AND 8-ACETYLGONIOTRIOL FROM GONIOTHALAMUS-GIGANTEUS (ANNONACEAE) - X-RAY MOLECULAR-STRUCTURE OF GONIOFUFURONE AND OF GONIOPYPYRONE

By use of brine shrimp lethality for activity-directed fractionation, three novel styryl-lactones which are cytotoxic to human tumour cells, goniofufurone, goniopypyrone, and 8-acetylgoniotriol, have been isolated from ethanolic extracts of the stem bark of Goniothalamus giganteus Hook, f., Thomas (Annonaceae). The structures were elucidated by IR, mass, 1H NMR, 13C NMR, and 2D NMR (1H-1H COSY, and 1H-13C HETCOR) spectra. The structures of goniofufurone and goniopypyrone, which represent unusual natural skeletons, were confirmed by X-ray crystallographic analysis, to help establish the relative configurations. Goniopypyrone was the most bioactive, showing nonselective ED50 values of ∼6.7 x 10-1 μg/ml in each of our three human tumour cell lines.