Ameliorative effect of Ruellia tuberosa L. on hyperglycemia in type 2 diabetes mellitus and glucose uptake in mouse C2C12 myoblasts

Ruellia tuberosa L. (RTL) exhibits a wide range of phytochemical activities, for example, on treatment of diabetes mellitus (DM), in Orient. There is, however, few study regarding the effect of RTL on glycemic‐related homeostasis in type 2 DM (T2DM). We investigated the effect of RTL aqueous and ethanolic extracts on hypoglycemia in high‐fat diet (HFD)‐fed plus streptozotocin (STZ)‐induced T2DM rats, and examined the effect of RTL on glucose uptake in tumor necrosis factor‐α‐induced insulin‐resistant mouse C2C12 myoblasts, a mouse skeletal muscle cell line. The administration of 100 or 400 mg kg BW(−1) day(−1) of RTL aqueous or ethanolic extracts once a day for 4 weeks significantly ameliorated hyperglycemia, hyperinsulinemia, and the insulin resistance (IR) index in diabetic rats. RTL either aqueous or ethanolic extract at a concentration of 25–800 μg/ml significantly improved glucose uptake in insulin‐resistant mouse C2C12 myoblasts, indicating inhibiting the IR in skeletal muscles. These evidences suggest that RTL ameliorates hyperglycemia in HFD/STZ‐induced T2DM rats may be attributed to the alleviation of IR in skeletal muscles.