Protective effects of Mentha piperita Linn on benzo[a]pyrene-induced lung carcinogenicity and mutagenicity in Swiss albino mice

The chemopreventive and antimutagenic effects of an aqueous extract of Mentha piperita leaves were evaluated by using 9 week medium term model of benzo[a]pyrene (BP)-induced lung tumors. Lung tumors were induced by a single subcutaneous injection in the scapular region with BP in newborn Swiss albino mice (<24 h old). The oral administration of Mentha extract (ME) showed a significant reduction in the number of lung tumors from an incidence of 67.92% in animals given only BP to 26.31%. The inhibition rate was 61.26% in ME treated group with respect to reference group (BP-alone). However, tumor multiplicity was reduced from 0.83 in the BP-alone group to 0.31 in the BP+ME group. Also, ME treatment reduced the frequency of BP-induced chromosomal aberrations and micronuclei in bone marrow cells and decreased the levels of lipoperoxides and increased sulfhydryl groups in liver as well as lung. In cell-free assays, ME showed strong scavenging activity for both the DPPH* and ABTS*+ radicals. ME had an IC50 value of 272 microg/ml in the DPPH* assay. The chemopreventive action and antimutagenic effects observed in the present study is attributed to the antioxidative and radical scavenging properties of ME.