Inhibition of tumour promotion and cell proliferation by plant polyphenols

The plant polyphenols: 2-hydroxy chalcone, quercetin and tannic acid exhibited varying antiproliferative effects on two mouse cell lines—NIH 3T3 and L929. Whilst 2-hydroxy chalcone and tannic acid (at 250 μM concentration) were able to exert 90% and 56% growth inhibition, respectively, quercetin at the same concentration had no effect on NIH 3T3 cells. However, these test compounds could exert significant growth inhibition on L929 cells at a concentration as low as 50 μM. At the highest concentration tested (250 μM), 2-hydroxy chalcone, quercetin and tannic acid showed 87%, 61% and 78% growth inhibition, respectively. The observed difference in potencies of the test compounds for the two cell lines indicated that their actions are cell line specific. When tested in vivo on mice, the order of potency of the test compounds in inhibiting benzo[a]pyrene-induced mouse skin carcinogenesis was tannic acid > 2-hydroxy chalcone > quercetin. No correlation was observed between the efficacy of the test compounds and lipid peroxidation in vivo.