Acute toxicity and anti-ulcerogenic activity of an aqueous extract from the stem bark of Terminalia superba Engl. and Diels (Combretaceae)
Terminalia superba is a plant used in traditional medicine to treat many illnesses particularly gastro-intestinal disorders. This study was aimed to evaluate the acute toxicity and gastric anti-ulcer activity of an aqueous extract of Terminalia superba (AETs). The LD50 was determined by the graphic method of Miller and Tainter (1944) and the calculation method of Dragsted and Lang (1957) in mice. The preventive anti-ulcerogenic action of the extract was assessed using four models of gastric ulcer induction namely HCl/Ethanol solution, indomethacin solution, pylorus ligation and cold restraint stress in rats. The LD50 obtained by the oral administration of AETs was 12.2 ± 0.21 g/kg b.w. and 12.33 ± 0.87 g/kg b.w. by the graphic method and the calculation method respectively. The administration of AETs intraperitoneally gave 1.97 ± 0.29 g/kg b.w. (graphic method) and 1.93 ± 0.21 g/kg b.w. (calculation method) as LD50s. The preventive gastric anti-ulcer study revealed that for doses ranging from 125 to 500 mg/kg body weight, EATs significantly (P<0.05) inhibited ulcers induced in the four models. The inhibition values were 96.25, 96.01, 98.10 and 96.75 % on ulcerations induced respectively by HCl/Ethanol, indomethacin, pylorus ligation and cold restraint stress at the dose of 500 mg/kg b. w. At the same dose, AETs significantly (P < 0.05) increased mucus production and reduced gastric acid secretion. Phytochemical screening of the aqueous extract of the stem bark of Terminalia superba showed the presence of polyphenols, tannins, flavonoids, quinones, coumarines, saponins, reduced sugar, sterols and polyterpenes. These results suggested that the preventive anti-ulcer activity of AETs may be due to a cytoprotective effect. The LD50s found indicated that the extract was not toxic and that the phytochemical coumpounds present in EATs could be responsible for its effects. In conclusion, the preventive gastric anti-ulcer and the non toxic effects of the aqueous extract of Terminalia superba could justify the use of this plant in traditional medicine to treat abdominal disorder and pains.
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