Antihyperglycemic and antioxidant effects of Talinum portulacifolium leaf extracts in streptozotocin diabetic rats: A dose-dependent study

Hexane, ethanolic and aqueous extracts of Talinum portulacifolium leaves were prepared and given individually at different doses to normal and streptozotocin (STZ) induced diabetic rats after an overnight fast. The blood glucose levels were measured at 0,1,2,3,4,5 and 6 h after the treatment. The hexane extract at a dosage of 0.5g/kg b.w has shown maximal blood glucose lowering effect (64.7%) in diabetes rats. The same dosage did not produce any hypoglycemic activity in normal rats. The antihyperglycemic activity of hexane extract of Talinum portulacifolium leaves was significantly higher than that of glibenclamide, an oral hypoglycemic agent. All the extracts exhibited dose dependent scavenging activities against 2,2-diphenly-1-picrylhydrazyl (DPPH) radicals, nitric oxide radicals and hydrogen peroxide. Further, all extracts had relatively lower reducing power, compared to that of ascorbic acid. The total phenolic content of hexane, ethanol and aqueous extracts were found to be 61, 100 and 114 mg/gm of the dry extract respectively. TLC of the above extracts using the DPPH as a spraying reagent revealed yellow spots against purple background indicating the presence of potent antioxidant compounds. In conclusion hexane extract of Talinum portulacifolium leaves possess both antihyperglycemic and antioxidant activites, while the ethanol and aqueous extracts possess only antioxidant activity.