Anti-tumor-promoting effects of phenylpropanoids on Epstein-Barr virus activation and two-stage mouse skin carcinogenesis

In our joint project in the search for anti-tumor promoters from natural pl ant sources, we carried out a primary screening of 12 phenylpropanoids isol ated from Boronia pinnata Sm. (Rutaceae) by examining their possible inhibi tory effects on Epstein-Barr virus early antigen (EBV-EA) activation induce d by 12-O-tetradecanoylphorbol-13-acetate in Raji cells. All tested compoun ds in this study showed inhibitory activity against the EBV activation even at 1 x 10 mol ratio without any cytotoxicity. Among 12 phenylpropanoids te sted, boropinal-C (1), boropinol-A (5), boropinol-C (9) and 3-(3'-methoxy-4 '-prenyloxy)phenyl-1-prop (10), all having a 4'-(3-methylbut-2-enyloxy) gro up, a so-called prenyloxy group, showed more potent activities. Furthermore , 3-(3'-methoxy-4'-prenyloxy)phenyl-1-prop (10) also exhibited remarkable i nhibitory effects on mouse skin tumor promotion in an in vivo two-stage car cinogenesis test. This investigation indicated that certain phenylpropanoid s might be valuable anti-tumor promoters. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.