Berberine is a benzyl tetra isoquinoline alkaloid which is widely used as an antimicrobial and an antidiarrhoeal. As berberine containing plants are virtually used in all forms of traditional medicine, our study aimed to examine the antioxidant activity of berberine using 2,2-diphenyl 1-picrylhydrazyl (DPPH) radical scavenging, nitric oxide scavenging, lipid peroxidation, superoxide scavenging, iron chelating activity and 2,2-azino bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) radical scavenging methods. The IC 50 values for all the models were calculated by regression analysis. In all the models tested, berberine showed its ability to scavenge the free radicals in a concentration dependent manner. The present study thereby justifies the therapeutic potential of berberine.

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Alcoholic extract of the stems of Coscinium fenestratum, a medicinal plant indigenous to India and Sri Lanka used in ayurveda and siddha medicine for treating diabetes, was studied for its carbohydrate metabolism effect and antioxidant status in streptozotocin–nicotinamide induced type 2 diabetic rats. Oral administration of C. fenestratum stem extract in graded doses caused a significant increase in enzymatic antioxidants such as catalase, superoxide dismutase, glutathione synthetase, peroxidase, and glutathione peroxidase and in the nonenzymatic antioxidants ascorbic acid, ceruloplasmin and tocopherol. Effects of alcoholic extract on glycolytic enzymes such as glucose-6-phosphate dehydrogenase, lactate dehydrogenase and hexokinase showed a significant increase in their levels, whereas a significant decrease was observed in the levels of gluconeogenic enzyme, glucose-6-phosphatase and alanine aminotransferase in treated diabetic rats. Serum creatinine and urea levels also declined significantly. This investigation demonstrates significant antidiabetic activity of C. fenestratum.

The antidiabetic potential of the alcohol root extract of Holostemma annulare Schum. (Asclepiadaceae), a medicinal plant widely used in more than 34 Ayurvedic preparations, was evaluated in the streptozotocinnicotinamide-induced type 2 diabetic model. Graded doses of the alcohol root extract were administered to normal and experimental diabetic rats for 15 days. A significant (p < 0.05) reduction was observed in the fasting blood glucose levels of normal as well as diabetic rats. Serum insulin levels were stimulated in the diabetic animals treated with the extract. Body weight, serum lipid profiles, serum urea and creatinine levels were estimated in extract-treated normal and diabetic rats. In addition, glycosylated hemoglobin and liver glycogen levels assessed in the extract-treated diabetic rats were compared with diabetic control and normal animals. Significant results were observed in the estimated parameters, thereby justifying the use of the plant in the treatment of diabetes mellitus.

The antihyperglycemic potential of the aqueous stem extract of Coscinium fenestratum Colebr. (Menispermaceae), a medicinal plant widely used in traditional Ayurveda and Siddha systems of medicine for the treatment of diabetes mellitus, was evaluated in the streptozotocinnicotinamide-induced type 2 diabetic model. Graded doses of the aqueous stem extract were administered to normal and experimental diabetic rats for 12 days. In extract-treated diabetic rats, an insulin-independent action with significant reduction in blood glucose, serum triglyceride, and cholesterol levels was observed. In addition, other parameters like change in body weight, thiobarbituric acid reactive substance levels, glycosylated hemoglobin and liver glycogen levels, assessed in the extract-treated diabetic rats, were compared with diabetic control and normal animals. Significant results were observed in the above parameters thereby justifying the use of the plant in the indigenous system of medicine.