Anticancer and antimutagenic activity of Silybum marianum L. and Eucalyptus camaldulensis Dehnh. against skin cancer induced by DMBA: In vitro and in vivo models.

The current study investigated the prospective effect of Silybum marianum L. and Eucalyptus camaldulensis Dehnh extracts against skin cancer. Skin cancer was induced by 7,12-dimethylbenz(a) anthracene (DMBA) in young Balb/c mice. Plant extracts were administered to animals orally, once/day (100mg/kg, 5 days/week) for the 20 weeks. Anticancer activity was examined via tumor progression, where antimutagenic activity was measured using 8-OHdG and sister chromatid exchange (SCE) levels. Eucalyptus camaldulensis Dehnh. leaves extract and Silybum marianum L. leaves extract significantly reduced 8-OHdG in cultured human lymphocytes in a dose-response manner (P<0.05). Similarly, the leave extracts of both plants significantly reduced chromosomal damage as measured by SCE levels (P<0.05). In the skin painting assay, the leave extracts of both plants significantly delayed the onset of tumors compared to DMBA treated group (P<0.05). The Silybum marianum leaves extract significantly reduced tumor incidence (P<0.01) and papilloma frequency (P<0.01) induced by DMBA. The Eucalyptus camaldulensis leaves extract significantly reduced the number of tumors per animal (P<0.05) and incidence of tumors (P<0.001). The in vitro and in vivo findings showed that leaves of Silybum marianum L. and Eucalyptus camaldulensis Dehnh. extracts might be a promising source for anticancer and antimutagenic agents against human cancer.