Effects of Kaempferia parviflora Extract on Glucose Transporters in Human Renal Proximal Tubular Cells
Kaempferia parviflora Wall. Ex. Baker is the one herb widely used as food supplements and for therapeutic purposes, including antioxidant, anti-inflammation, antiobesity, and antidiabetes. Kidney plays a crucial role in glucose reabsorption which is mainly mediated by the function of glucose transporters named sodium glucose co-transporter 2 (SGLT2) and facilitated glucose transport 2 (GLUT2). Therefore, blocking of SGLT2 is a potential target of anti- diabetes. This study was performed to determine whether K. parviflora extract (KPE) and its active compound (5, 7-dimthoxyflavone; DMF) inhibit SGLT2 and GLUT2 in human renal proximal tubular cells (HK-2 cells). The effects of KPE and DMF on SGLT2- and GLUT2-mediated [3H]-2-deoxyglucose (2DG) uptake were measured. The results showed that KPE inhibited SGLT2- and GLUT2-mediated [3H]-2-DG uptake with half maximal inhibition concentrations (IC50) of 124 μg/ml and 62 μg/ml, respectively. In addition, DMF at 50 μM significantly inhibited SGLT2 and GLUT2 transport functions. Treating the cells with KPE for 24 hours inhibited SGLT2 and GLUT2 transports. The inhibitory effects of KPE and DMF were not the results from cytotoxicity as the evidence showed that KPE and DMF did not reduce cell viability. In conclusion, KPE and DMF inhibit SGLT2- and GLUT2-mediated glucose transport in human renal proximal tubule.