Cancer chemopreventive activity of phenylpropanoids and phytoquinoids from Illicium plants

In our joint project involving search of anti-tumor promoters from natural plant sources, six phenylpropanoids and seven phytoquinoids isolated from three Illicium plants (Illiciaceae) were tested for their inhibitory activities against Epstein-Barr virus early antigen (EBV-EA) activation induced by 12-O-tetradecanoyl phorbol-13-acetate in Raji cells. All tested compounds showed inhibitory activity against the EBV-EA activation even at 1 X 10 mol ratio, and the inhibitory activity of their compounds was found to be more than that of beta-carotene. Two pherylpropanoids having prenyl group, 4-allyl-2-methoxy-6-(3methyl-2-butenyl)phenol (3) and 4-allyl-2,6-dimethoxy-3-(3-methyl-2-butenyl)phenoI (4), showed more potent activities as anti-tumor promoters (IC50 224 and 217 mol ratio/TPA, respectively). The presence of a prenyl moiety in the phenylpropanoids plays an important role in anti-tumor promoting activity as xanthone, coumarin and flavonoid previously reported. This investigation indicated that prenylated pherylpropanoids might be valuable as potential cancer chemopreventive agents. (C) 2004 Elsevier Ireland Ltd. All rights reserved.