Dietary factors are considered important environmental risk determinants for various diseases. Isoflavones are one of the biologically active polyphenolic plant constituents that possess potential chemopreventive properties against a wide variety of chronic diseases. In the present study we have evaluated the antimutagenic potential of soy isoflavones against benzo(a)pyrene (B[a]P) (125 mg/ kg) induced genotoxicity in Swiss albino mice. The effect of soy isoflavones was studied by in vivo bone marrow chromosomal aberration and micronuclei induction test. Using an alkaline unwinding assay we monitored the DNA strand breaks. Two doses of soy isoflavones (20 and 40 mg/kg b.wt) were given orally for seven days prior to the administration of B[a]P. Soy isoflavone inhibited the genotoxicity of B[a]P in terms of chromosomal aberration and micronucleus formation. DNA strand break levels in only B[a]P treated group remained significantly high f the control values (P <0.001). The pretreatment of soy isoflavone showed gradual reduction in strand breaks significantly (P <0.001) and dose dependently. Soy isoflavone pretreatment also decreased cytochrome P450 (CYP) content. The activity of CYP was also decreased dose dependently by pretreatment with soy isoflavone. The chemopreventive effect of soy isoflavone on the inhibition of CYP activity and DNA integrity mediate the possible mechanism of inhibition of genotoxicity.
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