Lesion of the gastric mucosa is the most prevalent side effect of aspirin. Flavonoids with actions such as antioxidant, free radical scavenger and lipid peroxidant inhibitor can prevent mucosal lesion caused by aspirin. In this research effect of quercetin, as the most abundant flavonoid in human diet, was investigated on preventing ulcerogenic effect of aspirin or Acetyl Salisylic Acid(ASA).

Eighteen male Wistar rats (220-330gr) were randomly divided into 3 groups (6 in each group). In all groups consumption materials were adminstrated only once in acute form. First and second groups, as control groups, received ASA vehicle (1ml, orally) and ASA suspension (300mg/kg, 1ml, orally) respectively. The third group had a pretreatment with quercetin (200mg/kg) half an hour before consumption of 300mg/kg ASA. After consumptiom the materials animals were kept 3hours, after that stomach was removed and was assessed for macroscopic and microscopis stomach mucosal lesions.

          Our results showed that, oral adminstration of ASA (300mg/kg) caused considerable stomach mucosal lesions (P<0.05) and pretreatment with quercetin decreased the lesions (P<0.05).

        Therefore quercetin can be effecttive in protecting stomach mucosa against ulcers caused by ASA. Although the mechanism of quercetin action is not known, it might be used for mucosal protection with further investigations.