ROLE OF POLYMORPHONUCLEAR LEUKOCYTES AND OXYGEN-DERIVED FREE-RADICALSIN THE FORMATION OF GASTRIC-LESIONS INDUCED BY HCL ETHANOL, AND A POSSIBLE MECHANISM OF PROTECTION BY ANTIULCER POLYSACCHARIDE/

This study examined the role of oxygen-derived free radicals in the pa thogenesis of gastric mucosal lesions induced by HCI/ethanol. Superoxi de dismutase, and catalase, and their combination reduced gastric lesi on formation in mice. Gastric lesions were also reduced in mice treate d with cyclophosphamide or anti-neutrophils, but not in mice treated w ith allopurinol or desulphated-carrageenan. Cobra venom factor did not reduce lesion formation. These results suggested that oxygen-free rad icals may contribute to the formation of gastric mucosal lesions induc ed by HCI/ethanol, and that oxygen radicals were generated from neutro phils but not from xanthine oxidase. Anti-ulcer pectic polysaccharide, bupleuran 2IIc, which was recently isolated from the roots of Bupleur um falcatum L., showed potent inhibition of HCI/ethanol-induced gastri c lesions in mice. Bupleuran 2IIc seemed to scavenge hydroxyl radical effectively. It was suggested that this anti-ulcer polysaccharide may provide protection to the gastric mucosa by scavenging oxygen-free rad icals.