Glucose Enzymatic Modulation by Vernonia amygdalina in Streptozotocin- Diabetic Wistar Rats

The present study examines the effect of some bioactive constituents of Vernonia amygdalina crude extract and fractions on enzymes involved in glucose metabolism and treatment of Diabetes Mellitus. Fresh Vernonia amygdalina leaves were extracted using ethanol. Four fractions from this extract were obtained by liquid-liquid fractionation technique using solvents of varying polarity and the bioactive compounds were identified by Gas Chromatography–Mass Spectrum (GC-MS) analysis. Resultant fractions were administered at 300 mg/kgBW to streptozotocin (60 mg/kg) induced diabetic wistar rats. The results shows that various fractions produced a fall in the fasting blood glucose level in diabetic rats; Chloroform (65.85%), ethyl acetate (69.65%) Benzene (45.59%) and Butanol (37.31%) and all fractions showed increase in the activity of glucose metabolic enzymes (hexokinase, pyruvate kinase, Glucose-6-phosphate dehydrogenase (G6PDH) and Diaphorase (NADPH) between 20–81%, significantly higher than that of the metformin (reference drug at 50 mg/kg). Administration of Crude ethanolic leaf extracts of Vernonia amygdalina at dose of 300 mg/kg produced a fall (81.45%) in the fasting blood glucose level and subsequent increase in glucose metabolic enzyme activity (hexokinase, pyruvate kinase, Glucose-6-phosphate dehydrogenase (G6PDH) and Diaphorase (NADPH) (20–35%) in the diabetic Wistar rats after 28 days of treatment. GC-MS analysis showed that the plant and its fractions possess hypoglycaemic bioactive constituents such as Phytol, Palmitic acid, stearic acid and oxirane. The findings suggest that Vernonia amygdalina extract reduced the hyperglycaemic effect of streptozotocin-induced diabetes through its effect on glucose metabolism by promoting enzymes of the glycolytic and the pentose phosphate pathway, a property attributable to its active chemical constituents.