Abstract: OBJECTIVE: To evaluate the efficacy of Pistacia atlantica Desf. oleoresin essential oil on peptic ulcer(PU) and its antibacterial effect on metronidazole-resistant Helicobacter pylori, as well as chemi-cal composition of the essential oil.METHODS: The essential oil was standardized using gas chromatography mass spectrometry(GC/MS) analysis. Acute toxicity of the essential oil was assessed in animal model. In vitro anti-Helicobacter pylori activity was performed through disc diffusion and minimum inhibitory concentration method. For gastroprotective assay, rats received Pistacia atlantica Desf. essential oil(25, 50 and 100 mg/kg orally) 1 h before induction of ulcer by ethanol.Macroscopic(ulcer index and protection rate) and microscopic examination were performed.RESULTS: The GC/MS analysis of the essential oil led to the identification of twenty constituents andα-pinene is predominant constituent. The essential oil was safe up to 2000 mg/kg. All Helicobacter pylori strains were susceptible to the essential oil and the MIC ranged from 275 to 1100 μg/m L. The ulcer index for treated groups was significantly reduced compared to control(P < 0.001) with EC50 value of 12.32 mg/kg. In microscopic examination, Pistacia atlantica attenuated destruction and necrosis of gastric tissue.CONCLUSION: Current study exhibited protective effect of standardized Pistacia atlantica essential oil against ethanol-induced gastric ulcer and its antibacterial activity on Helicobacter pylori. α-pinene might be the responsible agent.

Key words: Peptic ulcer, Pistacia, Oils, volatile, Oleoresins, Gastroprotective, Helicobacter pylori, Medicine, traditional