Comparison of antioxidant activity of insulin, Ocimum gratissimum L., and Vernonia amygdalina L. in type 1 diabetic rat model.

Diabetes mellitus (DM) is known to be associated with increase of oxidative stress products. The direction of effect of any treatment on these products could therefore be a reliable measure of its efficacy on DM. So the aim of this study was to investigate the activity of insulin, Ocimum gratissimum L. (OG) and Vernonia amygdalina L. (VA) on oxidative stress products.

Thirty-six female Wistar rats weighing 150-200 g were randomly divided into six groups of six rats each. Thirty rats were induced for type 1 DM (DM1) with a single intraperitoneal administration of 65 mg/kg body weight of streptozotocin. Group 1 was normal control and was administered distilled water while Group 2 served as DM1 control group; Groups 3, 4, 5 and 6 were diabetic rats treated with 208 mg/kg OG (DM1 + OG), 52 mg/kg VA (DM1 + VA), 208 mg/kg OG + 52 mg/kg VA (DM1 + OG + VA) and 0.16 IU insulin (DM1 + insulin) respectively. Determination of methemoglobin and sulfhemoglobin was achieved by the absorption spectrum principle. Red blood cell (RBC) catalase was assayed by continuous spectrophotometric method.

The RBC catalase concentration was significantly decreased in the DM1 and DM1 + VA groups when compared with the normal control. DM1 + OG significantly increased RBC-catalase when compared to DM1. The methemoglobin concentration was significantly reduced in the DM1, DM1 + VA, DM1 + OG + VA and DM1 + insulin groups when compared to the normal control group. The sulfhemoglobin concentration was significantly increased in the diabetic control and the diabetic treated groups when compared to the normal control. DM1 + OG reduced the sulfhemoglobin concentration when compared to DM1. The blood glucose concentration of all the diabetic groups was significantly raised compared to normal control. OG, VA and insulin significantly reduced the blood glucose concentration with the efficacy of OG and VA higher than insulin.

Adverse alteration of oxidative indices were observed in type 1 DM model. Treatment with OG and insulin showed potent antioxidant activity, while the hypoglycemic efficacy of OG and VA were higher than insulin.