Tumor chemopreventive activity of 3-O-acylated (−)-epigallocatechins

In order to seek promising cancer chemopreventive agents, we assessed the antitumor promoting activities of 3-O-octanoyl- or 3-O-(2-methyloctanoyl)-(−)-epigallocatechins, inhibiting markedly the activation of Epstein–Barr virus early antigen, in a two-stage mouse skin carcinogenesis assay. As a result, these derivatives inhibited a papilloma formation 1.3–1.6-fold more strongly than (−)-epigallocatechin gallate well established as anti-tumor promoter.