Anti-tumor promoting activities of isoflavonoids from Wistaria brachybotrys

Eight minor isoflavonoids (3-10) isolated from the knot of Wistaria brachybotrys were tested for their inhibitory effects on Epstein-Barr virus (EBV) activation induced by the tumor promoter, 12-O-tetradecanoyl-phorbol-13-acetate (TPA), in Raji cells as a primary screening test for anti-tumor-promoters (cancer chemopreventive agents), and all the tested compounds showed inhibitory activity. Of these compounds, pendulone (3) was further examined on the cell cycle of Raji cells, and indicated strong inhibition on the effect of the cell cycle induced by TPA. In addition, the compound showed potent anti-tumor-promoting activity for an in vivo two-stage carcinogenesis test of mouse skin using 7,12-dimethylbenz[a]-anthracene and TPA. Consequently, it suggests that 3 could be a valuable chemopreventive agent in chemical carcinogenesis.