Protective and antioxidant effects of Rhizophora mangle L. against NSAID-induced gastric ulcers

The bark of Rhizophora mangle, the red mangrove, has been used traditionally in folk medicine of Caribbean countries due to its antiseptic, astringent, haemostatic and antifungal properties. Aqueous extracts are rich in tannins and have been proven experimentally to possess antibacterial, wound healing and antiulcerogenic effects. This work was designed to determine the gastroprotective effect of Rhizophora mangle in a model of diclofenac-induced ulcers in rats and to study the mechanisms involved, using the proton pump inhibitor omeprazole as a comparison. The lyophilized extract was given by oral gavage (125 and 62.5mg/kg) three times at 12h intervals before administering diclofenac 100mg/kg. Pretreatment with the extract resulted in a significant decrease of the ulcerated area (P<0.01). Rhizophora mangle induced a recovery of PGE(2) levels, which had been depleted by diclofenac. No anti-inflammatory effect was observed ex vivo or in vitro. The highest dose of the extract provoked a marked increase in glutathione peroxidase and superoxide dismutase activity, which was comparable to omeprazole. Furthermore, lipid peroxidation levels were inhibited in a dose-dependent manner. These results suggest that the gastroprotective effect of Rhizophora mangle in this experimental model appears through an antioxidant and prostaglandin-dependent way.