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Aims: The study examines effect of aqueous-fraction of ethanolic extract of Balanites aegyptiaca stem-bark on enzymes of glucose metabolism in streptozotocin (STZ)-induced diabetic rats in a bid to ascertain its anti-hyperglycemic and possible mechanism of action.
Methodology: Diabetes was induced in male rats by intra-peritoneal injection of 60 mg/kg body weight of STZ. Dried powdered Balanites aegyptiaca stem-bark was defatted with hexane and extracted using ethanol followed by solvent-solvent fractionation with water and ethyl acetate. The aqueous fraction (ASF) obtained was subjected to acute toxicity on wistar rats using a gradient dosage, where 1/10th of lethal dose was calculated and used for the study. It was orally administered at a dose of 400 mg/kg body weight of diabetic rats, metformin (200 mg/kg body wt) serve as reference drug and diabetic/normal untreated rats received 10% dimethyl sulfurdioxide for the 28 days treatment period. On day 29th, rats were sacrificed; blood and liver samples were collected. Liver tissues were homogenized, centrifuged and the supernatants were used for assay of glucose metabolic enzymes while serum was used for biochemical markers estimations.
Results: Results obtained showed no death or lethal effect in the acute toxicity study up to a dose of 4000 mg/kg body wt. Therefore, the LD50 value was considered to be more than 4000 mg/kg body wt. Streptozotocin-induced diabetic rats treated with ASF showed a significant (P<0.05) reversal effect in activities of the glucose metabolic enzymes assayed compare to untreated diabetic rats. Glucokinase activity was enhanced (2.98±2.23 U/min/mg Protein) against untreated diabetic (2.22±0.02 U/min/mg Protein) as well as glycogen synthase (12.48±0.11 x10-2 U/min/mg Protein) against untreated diabetic (9.41±0.34 x10-2 U/min/mg Protein. Glucose-6-phosphatase activity was suppressed in the diabetic rats received ASF (0.26±0.03 U/min/mg Protein) compare to the untreated diabetic (1.44±0.05 U/min/mg Protein). Glycogen content of the treated diabetic rats was elevated to 13.77±0.32 mg/g liver against the diabetic untreated rats (10.69±0.32 mg/g liver). A significant reduction in fasting blood glucose was recorded from the ASF treated diabetic rats (290.4±18.4 mg/dL) compared to diabetic untreated rats (336.0±11.9 mg/dL).
Conclusion: The study suggested that Balanites aegyptiaca stem-bark may contained compound(s) that has the capacity to reverse the activity of glucose metabolic enzymes to exert antihyperglycemic activity.