4.5. Glucose Uptake Assay

Glucose uptake in HepG2 cells was assessed by using 2-NBDG (Sigma-Aldrich) according to the previous report [54] with a few modifications. In short, cells cultured in black 96-well plates were treated with PA in the presence of TFs (0–10 µg/mL) or metformin (5 µg/mL, positive control) for 24 h. Then cells were kept in glucose-free DMEM for 4h and stimulated by insulin (500 nM) for another 10 min. Following incubation with 50 nM 2-NBDG in glucose-free DMEM for 30 min, the cells were gently washed twice with cold PBS buffer to terminate reaction. The fluorescence was detected at an excitation wavelength of 485 nm and an emission wavelength of 535 nm.