THE FLAVONOID-RICH FRACTION OF VERNONIA AMYGDALINA LEAF EXTRACT REVERSED DIABETES-INDUCED HYPERGLYCEMIA AND PANCREATIC BETA CELL DAMAGE IN ALBINO WISTAR RATS.

Medicinal plant bioactive constituents are used as complements in the management of diabetes mellitus. This study investigated the effect of treatment with flavonoid-rich fraction of Vernonia amygdalina (VA) on blood glucose and pancreatic islet histopathology of STZ-induced diabetic rats. Forty-eight Wistar rats were randomly assigned to eight treatment groups. Forty two fasted rats were rendered hyperglycemic by a single intraperitoneal injection of STZ (40mg/kg.bw). Methanol crude extract, 30% methanol flavonoid-rich fraction, 50% methanol saponin-rich, 100% methanol glycoside-rich and butanol fractions of VA were administered by gastric intubation to five groups of the hyperglycemic rats at 200mg/kg.bw for crude extract and 75mg/kg.bw for fractions respectively while insulin was given intramuscularly at 5 IU/kg.bw. Diabetic control and normal control groups were administered DMSO. Hyperglycemic rats treated with the crude extracts and fractions were hypoglycemic by the end of the 28 days treatment period. The 30% methanol flavonoid-rich and 100% methanol glycoside-rich fractions showed greater anti-hyperglycemic activity of all the fractions. Pancreatic islet histology of diabetic control rats showed damaged islets shrunken in cell mass compared with the non-diabetic control rats which had numerous islet cell mass and well stained nuclei. Treatment with the flavonoid-rich fraction presented total recovery of the islet cell mass, better than the treatment with insulin and methanol crude extract which showed only partial recovery. This observation indicates that the flavonoid-rich fraction of VA leaf extract reverses hyperglycemia and regenerates pancreatic islet cell mass