Studies on possible protective effect of plant derived phenols and the vitamin precursors—β-Carotene and α-tocopherol on 7,12 dimethylbenz (a) anthracene induced tumour initiation events

Our earlier experiments have shown that the plant phenols—hydroxychavicol, eugenol, catechin, curcumin, and the vitamins—β-carotene and α-tocopherol—are potent inhibitors of polycyclic aromatic hydrocarbon (PAH) induced mutagenesis and carcinogenesis. In an attempt to elucidate their mode of action, we studied their effect on mouse skin DNA synthesis following 7,12 dimethylbenzanthracene (DMBA) treatment and ³H-7,12 dimethylbenzanthracene—DNA interaction in vitro (in the presence of mouse skin S9). With the exception of eugenol, all the phenols and vitamins tested inhibited ³H-DMBA-DNA interaction in vitro. In the DNA biosynthesis assay, of the chemopreventive agents tested only β-carotene effectively modulated DMBA suppressed DNA synthesis in the mouse skin. Our results indicate that the assay of DNA biosynthesis is not of predictive value with respect to the chemopreventive effect of a chemical, while assay of carcinogen—DNA interaction shows correlation between the chemopreventive property and the inhibition of the interaction of carcinogen with DNA.