Effect of an antidiabetic extract of Catharanthus roseus on enzymic activities in streptozotocin induced diabetic rats

Hypoglycemic activity was detected in dichloromethane:methanol extract (1:1 ) of leaves and twigs of Catharanthus roseus (family Apocynaceae), a tradit ionally used medicinal plant, using streptozotocin (STZ) induced diabetic r at model. Extract at dose 500 mg/kg given orally for 7 and 15 days showed 4 8.6 and 57.6% hypoglycemic activity, respectively. Prior treatment at the s ame dose for 30 days provided complete protection against STZ challenge (75 mg/ka/i.p. x 1). Enzymic activities of glycogen synthase, glucose 6-phosph ate-dehydrogenase, succinate dehydrogenase and malate dehydrogenase were de creased in liver of diabetic animals in comparison to normal and were signi ficantly improved after treatment with extract at dose 500 mg/kg p.o. for 7 days. Results indicate increased metabolization of glucose in treated rats . Increased levels of lipid peroxidation measured as 2-thiobarbituric acid reactive substances (TBARS) indicative of oxidative stress in diabetic rats were also normalized by treatment with the extract. (C) 2001 Elsevier Scie nce Ireland Ltd. All rights reserved.