IN VIVO AND IN VITRO ANTIOXIDANT ACTIVITIES OF COUMARIN ON CHEMICAL INDUCED HYPERGLYCEMIC RATS

The present study was aimed at investigating the antioxidant activities of coumarin in streptozotocin (STZ)-nicotinamide (NA) induced type 2 diabetic rats. Diabetes was induced in experimental rats by a single intraperitoneal (i.p.) injection of STZ (45 mg/kg body weight (b.w.)), 15 min after the i.p. administration of NA (110 mg/kg b.w.). Diabetic rats were administered coumarin intragastrically at 100 mg/kg b.w. for 45 days. The antioxidant activities of coumarin have been evaluated by using a range of in vivo assays and in vitro assays. In case of in vivo studies the levels of plasma thiobarbituric acid reactive substances (TBARS), lipid hydroperoxides (HP) and conjugated dienes (CD) were measured. The levels of vitamin C, vitamin E and reduced glutathione (GSH) in the plasma and tissues were assayed. In case of in vitro assays 2, 2¢-diphenyl-1-picrylhydrazyl radical (DPPH^•), 2, 2’-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) radical (ABTS^•+), hydroxyl radical, superoxide anion scavenging activity and reducing power were measured. In addition to that ascorbic acid and butylated hydroxyl toluene were used as the reference antioxidant radical scavenger compounds. Among the different concentration (10, 20, 30, 40, 50 μM), 50 μM of coumarin had significantly effective compared to other concentration in all in vitro assay. These findings suggest that coumarin possess in vivo and in vitro antioxidant activity as an effective free radical scavenger augmenting its therapeutic value.