Swertiamarin and quercetin combination ameliorates hyperglycemia, hyperlipidemia and oxidative stress in streptozotocin-induced type 2 diabetes mellitus in wistar rats

Ethnopharmacological relevance: Swertiamarin (Sw) and quercetin (Qu) have been isolated from different plants and are reported for their antidiabetic activities. The plants from which swertiamarin and quercetin were isolated are also traditionally used in the treatment of diabetes mellitus. Aim of the study: The present study is aimed to evaluate the synergistic effect of a combination of swertiamarin and quercetin (CSQ) on alpha-amylase in vitro and on streptozotocin (STZ) induced diabetes mellitus in vivo. Methods: Swertiamarin was isolated from the plant Enicostemma axillare and quercetin was procured in its pure form. Sw, Qu and CSQ were evaluated for in vitro alpha-amylase inhibitory activity. Based on the in vitro study results, CSQ was assessed for in vivo streptozotocin induced diabetes mellitus in Wistar rats. The effect of CSQ on blood glucose levels, body weight, serum biochemical parameters and antioxidant enzymes such as glutathione (GSH), superoxide dismutase (SOD), catalase, glutathione peroxidase (GPx) and lipid peroxide levels were estimated. The histopathological observations of pancreatic tissues were also made. Results: The purity of swertiamarin was confirmed by HPLC. The results showed that CSQ was found to possess high percentage of inhibition in an in vitro alpha-amylase inhibitory study. In a STZ-induced type 2 diabetes mellitus (T2DM), body weight of rats in CSQ treated and control groups were unaltered. A marked reduction in the blood glucose levels was observed in the CSQ treated groups on 14th and 28th day. Decrease in the levels of low-density lipoprotein (LDL), triglycerides, total cholesterol and an increase in high-density lipoprotein (HDL) cholesterol level was observed in a dose dependant in CSQ treated groups. However, CSQ treated groups could significantly improve antioxidant protection by increasing the levels of serum GSH, SOD, Catalase and GPx and decreasing the levels of lipid peroxide (p<0.05). In the histopathological study, the pancreatic islets of Langerhans and vacuolization have shown significant increase in both the treated groups. Conclusions: The combination of swertiamarin and quercetin (CSQ) has proven a preventive and therapeutic effect against T2DM and suggests that this is a potential combination of phytoconstituents for excellent hypoglycemic activity in T2DM.