Antioxidant and anti-hyperglycemic potential of pulp extracts of Irvingia wombolu fruits
The present study aimed at evaluating the in vitro antioxidant and in vivo anti-hyperglycemic potential of pulp extracts of Irvingia wombolu fruits on streptozotocin-induced diabetic rats. After phytochemical screening, aqueous and hydroethanolic extracts of I. wombolu were analysed for polyphenol content. Antioxidant activity was assessed using three methods. The capacity of the extracts to scavenge hydroxyl radical and to chelate metal was also evaluated. Diabetes was induced in 25 rats by intravenous administration of streptozotocin (50mg/kg body weight). The effect of the extracts on blood glucose levels of diabetic rats was monitored at various time intervals for 5h after administration of the extract (first single dose of 400 mg/kg/day). In addition, total cholesterol (TC), HDL cholesterol, triglyceride (TG), MDA, hydroperoxides and plasma antioxidant capacity was determined after a three-week period. The aqueous extract showed the higher polyphenol content while the hydroethanolic extract had the best in vitro antioxidant capacity. Glucose levels of treated diabetic rats significantly decreased 3h after administration of extracts (P<0.05). There was no significant difference in TC, HDL and LDL cholesterol between diabetic control and treated diabetic rats. In contrast, extracts significantly reduced triglyceride. Treatment with extracts significantly reduced atherogenic risk predictor indices. Plant extracts significantly reduced MDA and hydroperoxide levels. Antioxidant capacity of blood plasma significantly increased after administration of aqueous extract. This study suggests that I. wombolu pulp not only could be a good source of antioxidants, but might also have glucose lowering property, with the best in vivo activity attributed to aqueous extract.