RESUMEN
In the present study, a hydroalcoholic extract of ocimum sanctum leaves has been investigated for its antioxidant activity in animal models of peptic ulcer with the aim of exploring a possible correlation between its antioxidant and antiulcer activities. Gastric ulcers were produced in rats by ethanol treatment and pyloric ligation whereas duodenal ulcers were produced in guinea pigs by histamine treatment. The animals were divided into six groups of six animals each in all these three models of peptic ulcer. Group I served as diseased control in which distilled water (10 ml/kg) orally was administered as placebo. Group II, III and IV received the test drug (ocimum sanctum leaf extract) in doses of 50 mg/kg, 100 mg/kg and 200 mg/ kg respectively orally once daily for 7 days. Group V was administered ranitidine (10 mg/kg orally) once daily for 7 days and served as standard for comparison. Group VI consisted of healthy control for baseline malondialdehyde (MDA) and superoxide dismutase (SOD) levels. The antioxidant activity was by evaluated estimating plasma MDA in ethanol treated rats and histamine treated guinea pigs and estimating SOD in pyloric ligated rats and histamine treated guinea pigs. In ethanol treated rats, ocimum sanctum leaf extract (100 mg/kg & 200 mg/kg) significantly decreased the levels of MDA to 2.45 +/- 0.29 nmole/ml and 2.40 +/- 0.14 nmole/ml respectively in comparison to 4.87 +/- 0.06 in the diseased control. Similarly, in the histamine treated guinea pig group, the same doses of the extract significantly lowered the levels of MDA to 2.45 +/- 0.12 nmole/ml and 2.37 +/- 0.16 nmole/ml respectively when compared to 4.66 +/- 0.11 in the diseased control. The extract (100 mg/kg & 200 mg/ kg) also increased the levels of SOD in pyloric ligated rats to 1.78 +/- 0.12 U/ml and 1.89 +/- 0.08 U/ml respectively when compared to 1.29 +/- 0.06 U/ml in the diseased control. In the histamine treated guinea pig group also, the same doses of the extract produced a rise in the SOD levels to 2.10 +/- 0.11 U/ml and 2.20 +/- 0.14 U/ml respectively when compared to 1.32 +/- 0.07 in the diseased control. Since lowered levels of MDA and increased levels of SOD signify antioxidant activity, the antiulcer activity of ocimum sanctum might be due to this mechanism.