Protective effect of a water-soluble polysaccharide from Salvia miltiorrhiza Bunge on insulin resistance in rats

Oxidative stress is associated with insulin resistance (IR) and is thought to contribute to the development and progression toward type 2 diabetes (T2DM). This study was undertaken to isolate the bioactive polysaccharide (SMPW1) from Salvia miltiorrhiza Bunge and investigated its protective effects on IR model in rats induced by tert-butyl hydroperoxide (t-BHP). In vivo animal experiments showed that SMPW1 (50 and 100 mg/kg) possessed high antioxidative and protective capacity against the injury induced by t-BHP, as reflected in the increased expression or activities of catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), and the decreased formation of malondialdehyde (MDA) in serum and liver homogenates. In addition, SMPW1 (50 and 100 mg/kg) also attenuated IR and the morphological injury of liver and pancreas induced by t-BHP, and improved insulin sensitivity index. In conclusion, SMPW1 can protect against the development of T2DM and improve IR via reduction of oxidative stress.