Inhibitory effects of Azadirachta indica on DMBA-induced skin carcinogenesis in Balb/c mice

Male Balb/c mice were divided into four groups on the basis of their respective treatments wherein mice of Group I served as controls. For induction of skin tumors, mice of Group II and IV were injected sub-cutaneously with 7,12-dimethylbenz(a)anthracene (DMBA). Mice of Group III and IV were administered aqueous Azadirachta indica leaf extract (AAILE) thrice a week throughout the experiment. After 14 weeks of the first DMBA injection, Group II and IV mice developed tumors. In the tumor-bearing mice that received AAILE (Group IV), a significant reduction in mean tumor burden and tumor volume was observed. The tumors were confirmed to be papillomas and interestingly, the extent of hyper-chromatia was observed to be much more in skin tumors of Group II mice vis a vis the mice receiving AAILE. An increase in the extent of lipid peroxidation was observed in tumorous tissue of Group IV when compared to that of Group II mice. Glutathione (GSH) content and the activities of GSH-based antioxidant enzymes viz. glutathione peroxidase (GPx) and glutathione reductase (GR) increased significantly in the skin tissues of all the groups of mice when compared to control counterparts. Catalase activity was found to decrease significantly in the skin of mice, which received AAILE treatment only (Group III). Activity of super-oxide dismutase (SOD) decreased significantly in all the tumorous tissues (Group II and IV mice). In light of the above observations, the role of AAILE in inhibition of DMBA-induced skin carcinogenesis is discussed in the present study.