An antitumor promoter from Moringa oleifera Lam.

In the course of studies on the isolation of bioactive compounds from Phili ppine plants, the seeds of Moringa oleifera Lam. were examined and from the ethanol extract were isolated the new O-ethyl-4-(alpha-L-rhamnosyloxy)benz yl carbamate (1) together with seven known compounds, 4(alpha-L-rhamnosylox y)-benzyl isothiocyanate (2), niazimicin (3), niazirin (4), beta-sitosterol (5), glycerol-1-(9-octadecanoate) (6), 3-O-(6'-O-oleoyl-beta-D-glucopyrano syl)-beta-sitosterol (7), and beta-sitosterol-3-O-beta-D-glucopyranoside (8 ). Four of the isolates (2, 3, 7, and 8), which were obtained in relatively good yields, were tested for their potential antitumor promoting activity using an in vitro assay which tested their inhibitory effects on Epstein-Ba rr virus-early antigen (EB V-EA) activation in Raji cells induced by the tu mor promoter, 12-O-tetradecanoyI-phorbol-13-acetate (TPA). All the tested c ompounds showed inhibitory activity against EBV-EA activation, with compoun ds 2, 3 and 8 having shown very significant activities. Based on the in vit ro results, niazimicin (3) was further subjected to in vivo test and found to have potent antitumor promoting activity in the two-stage carcinogenesis in mouse skin using 7,12-dimethylbenz(a)anthracene (DMBA) as initiator and TPA as tumor promoter. From these results, niazimicin (3) is proposed to b e a potent chemo-preventive agent in chemical carcinogenesis. (C) 1999 Else vier Science B.V. All rights reserved.