Bioassay-guided Isolation of the Antidiabetic Active Principle from Salvia miltiorrhiza and its Stimulatory Effects on Glucose Uptake Using 3T3-L1 Adipocytes

Abstract

Natural products, which reduce hyperglycemia by enhancing the glucose uptake in peripheral tissues, have been considered to be effective for treatment of Type-2 Diabetes Mellitus. Salvia miltiorrhiza (Labiatae), danshen, has been widely used traditional Chinese medicine for the treatment of various cardiovascular and cerebrovascular diseases. In the present study, different extracts of Salvia miltiorrhiza root were investigated for their ability to enhance glucose uptake in differentiated 3T3-L1 adipocytes. An in vitro bioassay guided fractionation approach was adapted to isolate the active principle of Salvia miltiorrhiza using extensive column chromatographic techniques. The structure of active compound was elucidated using various spectroscopic methods (ESI-MS, MALDI-ToF, 1H-NMR, 13C-NMR, COSY, TOCSY, HETCOR) and determined to be magnesium salt of salvianolic acid B (SAB). SAB showed concentration dependent increase in glucose uptake in 3T3-L1 adipocytes. The efficacy of the active principle was also evaluated for its antidiabetic activity in streptozotocin-induced diabetic rats. SAB (25 mg/kg) significantly improved the glucose tolerance in diabetic rats (*p<0.05, ** p<0.01). The SAB treatment group showed significantly lower (*p<0.05) blood glucose levels over 120 min as compared to diabetic control group. Thus, these results suggested that SAB has thepotential to be developed as a potential glucose-lowering agent by increasing glucose uptake in peripheral tissues in the treatment of diabetes mellitus.