Radical scavenging and gastroprotective activity of methanolic extract of Gmelina arborea stem bark

Abstract

Background: Gmelina arborea (GA) is widely used in traditional medicine for treating a number of ailments including gastrointestinal tract disorders.

Objective: To evaluate the gastroprotective effect of GA stem bark against ethanol-induced gastric ulcer in Wistar rats.

Materials and methods: All animals were fasted for 36 h and received GA extract 250 and 500 mg/kg body weight (bw), 1 h before the administration of ethanol. The animals received ranitidine 50 mg/kg bw which served as the standard. The rats were sacrificed after 4 h. Then, the injuries to the gastric mucosa were estimated through gross evaluation of ulcer lesions and histology. The antioxidant parameters such as level of lipid peroxidation, superoxide dismutase (SOD), reduced glutathione (GSH), and glutathione peroxidase (GPx) in gastric tissue were also determined.

Results: GA treatment at a dose of 500 mg/kg bw offered 91.98% inhibition of ulcer formation, which is higher than that of ranitidine. The ethanol treatment extensively increased lipid peroxidation and it was significantly (P < 0.01) reduced in GA-treated group that eventually helped to prevent free radical accumulation. The GA enhanced the gastric mucosal antioxidant system, as indicated by a dose-dependent increase in the level/activities of GSH, GPx, and SOD. GA also attenuated the severity of histological signs of cell damage. Further, GA extract showed in-vitro 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity with IC50 value of 124.39 μg/ml.

Conclusion: The results indicate that the gastroprotective effect of GA is probably related to its antioxidant activities that protect gastric mucosa against oxidative damage and antilipid peroxidative activity that maintain membrane integrity.

Keywords: Antioxidant system; Ethanol; Gastric ulcer; Gmelina arborea; Lipid peroxidation.

Fig. 1

Effect of Gmelina arborea on 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity. Values are expressed as mean ± standard deviation for six animals.

Fig. 2

Effect of Gmelina arborea on the prevention of gastric ulcer. Gastric mucosa of (A) normal animals showing absence of ulcers; (B) ethanol alone administered control animals showing severe ulceration as reddish mucosal lesions; (C) standard drug ranitidine (50 mg/kg bw.) treated animals with less intense ulceration; (D) G. arborea extract low concentration (GALC – 250 mg/kg bw.) showing mild ulceration with short mucosal lesions; (E) G. arborea extract high concentration (GAHC – 500 mg/kg bw.) displaying minor ulceration.

Fig. 3

The protective effect of Gmelina arborea on histological evaluation of rats' stomach in ethanol-induced ulcer model. Microscopic appearance of H & E stained (×400) gastric mucosa of (A) normal animals showing normal appearance (B) ethanol alone administered control animals displaying severe erosions associated with vacuole formation, inflammatory changes, and severe necrosis. (C) standard drug ranitidine (50 mg/kg bw.) treated animals showing mild vacuolation and inflammatory changes, but no necrosis (D) G. arborea extract low concentration (GALC – 250 mg/kg bw.) treated animals showing mild necrosis and vacuolation (E) G. arborea extract high concentration (GAHC – 500 mg/kg bw.) treated animals showing almost normal appearance of gastric mucosa.