Anti-tumor promoting effects of naphthoquinone derivatives on short term Epstein-Barr early antigen activation assay and in mouse skin carcinogenesis

In continuation of our studies of natural and synthetic products as cancer chemopreventive agents, we have examined a number of naphthoquinone derivatives including monomeric, dimeric and tetrameric naphthaquinones occurring in the Diospyros and other selected plant genera. Several synthetic naphthoquinones were also evaluated. Initially these compounds were tested for in vitro anti-tumor promoting effect on Epstein-Barr virus early antigen activation produced by the tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) and thereafter in in vivo on two-stage mouse skin carcinogenesis. Our studies show some of these compounds have potent anti-tumor promoting activity.