Chemomodulatory action of curry leaf (Murraya koenigii) extract on hepatic and extrahepatic xenobiotic metabolising enzymes, antioxidant levels, lipid peroxidation, skin and forestomach papillomagenesis

Curry leaf (Murraya koenigii) is commonly used in India as a natural flavoring agent for various food preparations. Drinking water containing 10% and 20% fresh crude curry leaf aqueous extract was given to Swiss albino mice to investigate its ability to modulate the level/activities of drug metabolising Phase I enzymes (Cytochrome P450, Cytochrome b5, Cytochrome P450 reductase and Cytochrome b5 reductase), Phase II enzymes (Glutathione S- transferase and DT- diaphorase), antioxidant parameters (Reduced glutathione, Superoxide dismutase, Catalase, Glutathione peroxidase, Glutathione reductase), lactate dehydrogenase and lipid peroxidation changes. The level of glutathione, glutathione S-transferase and DT-diaphorase was examined also in the extrahepatic organs viz., forestomach, kidney and lung. There was a significant increase in the activities of acid soluble sulfhydryl (-SH) content (from P < 0.05 to P < 0.001), glutathione- S transferase and DT-diaphorase (from P < 0.005 to P < 0.001). Antioxidative parameters were also elevated above basal value being: superoxide dismutase (P < 0.005), catalase (P < 0.001), Glutathione peroxidase (P < 0.005), and glutathione reductase (P < 0.005). Level of lipid peroxidation and lactate dehydrogenase decreased significantly. Anticarcinogenic potential of curry leaf was evaluated adopting the protocol of Benzo(a)pyrene induced forestomach and 7,12 Dimethylbenz(a)anthracene (DMBA) induced skin papillomagenesis. Chemopreventive response was measured by tumor burden (papillomas/mouse), and by the percentage of tumor bearing animals. Both the investigated dose levels of curry leaf showed a significant reduction in tumor burden (P < 0.001) as well as tumor incidence at both the tumor model system studied. Our studies strongly suggest that the curry leaf can be useful for the prevention of human stomach and skin cancers.