Mechanism of action of antiulcer activity of bark extracts of Manilkara hexandra against experimentally induced gastric ulcers in rats.

The present study was designed to explore the mechanism of action of bark extracts of Manilkara hexandra Roxb. against experimentally-induced gastric ulcers. The bark extracts were tested against aspirin- and ethanol-induced gastric ulcer models and histamine infusion-induced gastric acid secretion model in rats. The acetone aqueous extract (AE) of the drug (500-800 mg/kg) and ether insoluble extract (E2) (500-800 mg/kg) were administered orally against all the above mentioned models. The bark extracts have been found to be very effective in inhibiting gastric ulceration induced by aspirin and ethanol. This is evident from reduction (p< 0.001) in ulcer index parameter. In addition, extract E2 significantly reduced stomach thiobarbituric acid reactive substance (TBARs) in above models indicating free radical scavenging property of the drug. Extract E2 showed significant gastro protective effect against histamine infusion-induced gastric ulceration as evident from reduction in ulcer index. Besides, significant reduction in acid secretory parameters such as total acidity, total acid output and volume of gastric secretion were also observed at every 30 min. interval and at the end of 2 hours of experiment. Along with this parameters, mucin activity (TC: PR ratio) was also found to be significantly increased leading to gastric mucosal protection. It is concluded from this study that the drug possesses antiulcer activity in different gastric ulcer models. The antiulcer activity of the drug can be attributed to free radical scavenging property, inhibition of acid secretory parameters and strengthening of gastric mucosal barrier.