Protective role of luteolin on the status of lipid peroxidation and antioxidant defense against azoxymethane-induced experimental colon carcinogenesis

The modifying effect of dietary exposure to a flavonoid, luteolin (LUT) during the azoxymethane (AOM)-induced colon carcinogenesis was investigated in this study. Aberrant crypt foci (ACF), lipid peroxidation (LPO), enzymic and non-enzymic antioxidants and histopathological analysis were performed. Colon carcinogenesis was induced by injecting 15 mg/body kg weight of AOM, intraperitoneally (i.p.), once in a week for 3 weeks in male Balb/c mice. AOM-induced mice were treated with LUT (1.2 mg of LUT/kg body weight/day orally). After the experimental period, frequency of ACF, levels of thiobarbutaric acid reactive substances (TBARS) and hydroxy radical (OH˙) were found to be increased, whereas glutathione (GSH), Vitamins C, E and A were decreased in the plasma and colon of AOM-induced mice. However, LUT treatment to AOM-induced mice significantly decreased the incidence of ACF, levels of TBARS and OH˙ with a concordant increase in non-enzymic antioxidants in plasma and colon tissue. The activities of the antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione reductase (GR) were found to be decreased due to the induction of colon cancer in mouse. LUT treatment ameliorated the activities of these antioxidant enzymes. The histological study revealed a significant increase in the enlarged nuclei and hyperchromatism of cells in AOM-induced mice whereas LUT significantly reduced the signs in the colon. The immunohistochemical expression of MDA-DNA adduct was studied. In AOM-induced group, the expression was increased and treatment with LUT decreased significantly. The present study depicts that LUT can act as an effective chemopreventive agent against colon cancer.