Evaluation of the role of nitric oxide and antioxidation in the antiulcer activity of Ocimum sanctum leaves: an experimental study

Ocimum sanctum Linn. (O. sanctum) is a plant used in the traditional systems of medicine for healing several ailments. In the present study, the antiulcer activity of 50, 100, and 200 mg/kg doses of the aqueous extract (AE) of O. sanctum leaves was evaluated using ethanol and aspirin-induced ulcer models. The role of nitric oxide (NO) in the antiulcer activity of O. sanctum was evaluated by administering Nω-nitro-L-arginine-methyl ester hydrochloride (L-NAME), a NO synthase inhibitor, to AE treated rats before inducing ulcers by ethanol. The myeloperoxidase (MPO) and malonylaldehyde (MDA) levels were measured in AE treated rats in the aspirin-induced ulcer model so as to evaluate the role of antioxidation in the antiulcer activity. AE showed a dose-dependent and significant (p < 0.05) decrease in the ulcer index (UI) and increase in the percentage protection (PP) compared to the control group, in both the animal models employed. L-NAME pretreatment did not cause any significant (p < 0.05) change in the antiulcer activity of AE. The levels of MPO and MDA were significantly (p < 0.05) reduced by 100 and 200 mg/kg doses of the AE suggesting an antioxidant mechanism in its antiulcer activity. The bioactive phytochemicals isolated from the leaves may be responsible for the gastroprotective action of O. sanctum. The results of the study confirm the ethnopharmacological claim of O. sanctum leaves being effective in the treatment of peptic ulcer disease.