Aqueous root extracts of Dicoma anomala (Sond.) extenuates postprandial hyperglycaemia in vitro and its modulation on the activities of carbohydrate-metabolizing enzymes in streptozotocin-induced diabetic Wistar rats

Abstract

Dicoma anomala Sond (Asteraceae) is widely incorporated as a treatment for diabetes mellitus among the Basotho tribe of the Eastern Free State Province, South Africa. The study examined the antidiabetic effect of the plant via the in vitro inhibition of α-amylase, and α-glucosidase as well as against streptozotocin (STZ)-induced diabetic Wistar rats. The in vitro antidiabetic activity of the plant is via the inhibition of α-amylase, and α-glucosidase using water, ethanol, hydro-ethanol and methanol extracts. The effect of administration of aqueous root extract of Dicoma anomala (AQRED) at 125, 250, and 500mg/kg bodyweight (b.w.) on water consumption, feed intake, body-weight, blood glucose, carbohydrate-metabolizing enzymes, antioxidant enzymes, glycosylated haemoglobin and lipid profiles was determined in STZ (60mg/kg b.w.)-induced diabetic rats with comparison with glibenclamide (5mg/kg b.w.). While all the extracts of D. anomala showed activity against α-amylase and α-glucosidase, water extract revealed the most effective inhibition with an IC50 of 51.90 and 27.41μg/mL respectively. The water extract displayed competitive and non-competitive inhibitors of α-amylase and α-glucosidase respectively. AQRED reversed towards normal control the elevated food/water intake, blood glucose levels, lipid peroxidation, lipid profiles, glycosylated haemoglobin and activities of gluconeogenesis enzymes with a concomitant decrease in body-weight, activities of enzymatic antioxidants, glycolytic enzymes as well as the high-density lipoprotein-cholesterol level brought-about by STZ administration. The result of our findings proved the antihyperglycaemic activity of the plant and therefore validates the folkloric usage of the herb.