Biological activities of salvianolic acid B from Salvia miltiorrhiza on type 2 diabetes induced by high-fat diet and streptozotocin

Context: Salvia miltiorrhiza Bge. (Labiatae) has been widely used for treating diabetes for centuries. Salvianolic acid B (SalB) is the main bioactive component in Salvia miltiorrhiza; however, its antidiabetic activity and possible mechanism are not yet clear. Objective: To investigate the effects of SalB on glycometabolism, lipid metabolism, insulin resistance, oxidative stress, and glycogen synthesis in type 2 diabetic rat model. Materials and methods: High-fat diet (HFD) and streptozotocin-induced diabetic rats were randomly divided into model group, SalB subgroups (50, 100, and 200 mg/kg), and rosiglitazone group. Results: Compared with the model group, SalB (100 and 200 mg/kg) significantly decreased blood glucose (by 23.8 and 21.7%; p<0.05 and p<0.01) and insulin (by 31.3 and 26.6%; p<0.05), and increased insulin sensitivity index (by 10.9 and 9.3%; p<0.05). They also significantly decreased total cholesterol (by 24.9 and 27.9%; p<0.01), low-density lipoprotein cholesterol (by 56.2 and 64.6%; p<0.01), non-esterified fatty acids (by 32.1 and 37.9%; p<0.01), hepatic glycogen (by 41.3 and 60.5%; p<0.01), and muscle glycogen (by 33.2 and 38.6%; p<0.05), and increased high-density lipoprotein cholesterol (by 50.0 and 61.4%; p<0.05 and p<0.01), which were originally altered by HFD and streptozotocin. In addition, SalB (200 mg/kg) markedly decreased triglyceride and malondialdehyde (by 31.5 and 29.0%; p<0.05 and p<0.01), and increased superoxide dismutase (by 56.6%; p<0.01), which were originally altered by HFD and streptozotocin. Discussion and conclusion: The results indicate that SalB can inhibit symptoms of diabetes mellitus in rats and these effects may partially be correlated with its insulin sensitivity, glycogen synthesis and antioxidant activities.