Effect of dietary Polyphenon E and EGCG on development of benzo[ a]pyrene induced lung tumors in A/J mice

Abstract

In this study, we compared the chemopreventive activities of Polyphenon E (Poly E), (−)-epigallocatechin-3-gallate (EGCG) and Polyphenon E without EGCG (Poly E-EGCG) on the development of benzo(a)pyrene (B( a)P)-induced lung tumors in A/J mice. One week after carcinogen treatment, A/J mice were fed with 0.975% (wt/wt) EGCG, 0.525% (wt/wt) Poly E-EGCG or 1.5% (wt/wt) Poly E in AIN-76A purified powder diet for 24 weeks. Poly E significantly decreased both tumor multiplicity (52.2%, p<0.001) and tumor load (64.0%, p<0.001), while EGCG or Poly E-EGCG did not significantly inhibit lung tumor multiplicity. EGCG was more stable in a complex mixture (Poly E) than as a pure compound. EGCG was ineffective when administered by diet likely due to its instability. Thus, the efficacy of EGCG on lung tumorigenesis requires the presence of other tea catechins.