Abstract: OBJECTIVE: To investigate the efficacy of the extract from Ononis spinosa L.(O. spinosa) on ethanol-induced gastric ulcer in rats.METHODS: Phytochemical constituents of the extract from O. spinosa were analyzed using liquid chromatography-mass spectrometry. Rats were classified into 4 equal groups; ulcer control received oral vehicle; positive control was administered with 40 mg/kg esomeprazole(standard drug)and 2 groups received 0.5 and 1 g/kg of O. spinosa extract, respectively. Gastric ulcer was induced by absolute ethanol(5 mL/kg) orally to all groups.Measurement of ulcer index, cyclooxygenase-2(COX-2) expression and determination of total glutathione level in gastric mucosa were performed.RESULTS: Oral administration of the extract from O. spinosa at doses 0.5 and 1 g/kg lowered the ulcer indices by 80.39% and 98.71%, respectively,compared to 67.89% by esomeprazole(40 mg/kg).Histologically, treatment with the extract decreased necrosis and hemorrhage in mucosa and edema and infiltration by inflammatory cells in submucosa. Using immunohistochemical technique, it was demonstrated that COX-2 expression increased in mucosa of animals treated with the extract as well as by esomeprazole. O. spinosa and esomeprazole increased total glutathione level in the stomach compared to control. Ononin was the major compound of the extract followed by trifolirhizin, myricitrin, gentisic acid, cycloartenol and quercetin.CONCLUSION: The present study demonstrated that the extract from O. spinosa was able to protect gastric mucosa from ethanol injury by at least 2 mechanisms, namely the induction of COX-2 and decreasing oxidative stress in the stomach.

Key words: Ononis;;Stomach ulcer;;Cyclooxygenase 2;;Ethanol;;Ulcer index