Cytoprotective and Antioxidant Properties of the Stem Bark Aqueous extract of Khaya grandifoliola (Meliaceae) in Rats

Aims: To evaluate the qualitative chemical composition of the aqueous extract of the stem bark of Khaya grandifoliola and test the antiulcer actions on gastric lesions induced by HCl/Ethanol, HCl/Ethanol/Indomethacin, indomethacin, absolute ethanol, cold/restraint stress and pylorus ligation in experimental Wistar rats.

Study Design: Random allocation of male rats to groups of five rats each.

Place and Duration of Study: Department of Animal Biology and Physiology, Animal Physiology Laboratory (Gastroenterology Unit), University of Yaoundé 1, between November 2014 and May 2015.

Methodology: Gastric ulcers were produced in the glandular regions of rat stomachs using standard models of gastric ulcer induction. Ulcers produced were scored and mucus production and the severity of ulceration were compared between control groups and those given the plant extract or reference drugs. Oxidative stress parameters (superoxide dismutase (SOD), malondialdehyde (MDA), reduced glutathione (GSH), catalase (CAT)) were measured in tissue samples of rats subjected to the cold/restraint stress method.

Results: Phenols, saponinins, flavonoids, proteins, acids, anthocyanins, tannins, alkaloids, ketones, sugars, coumarins, quinones, and amino acids were among the phytochemicals detected. The extract (250–500 mg/kg) inhibited the formation of gastric ulcers and significantly reduced the ulcer index in all models used (81.8% (p <0.001) with HCl/ethanol; 88.2% (p <0.001) with absolute ethanol; 100% (p <0.05) with HCl/ethanol/indomethacin; 72.6% with cold/restraint stress ulcers, and 69.6% (P<0.01) with pylorus ligation at the highest dose of 500 mg/kg. Gastric acidity significantly (p<0.01) dropped from 88 mEq/L in the controls to 34 mEq/L at the dose of 500 mg/kg. In cold/restraint-induced stress, K. grandifoliola (500 mg/kg) lowered the increased levels of malondialdehyde (MDA) from 2.90 (control group) to 0.46 nmol/g tissue. The reduced levels of catalase were also significantly improved in rats treated with extract.

Conclusion: K. grandifoliola aqueous extract possesses gastric antisecretory potential. Its cytoprotective activity can be attributed to its ability to increase the antioxidant status and to enhance gastric mucosal defense possibly through the mediation of endogenous prostaglandins.