Fig. 4. Effects of RSV, R3G and R4G treatment on cellular glucose uptake, glycogen synthesis and ROS levels in insulin-resistant HepG2 cells. After cells were incubated with 1 × 10⁻⁶ mol L⁻¹ insulin for 24 h, the medium was discarded and was further grown with 1 μM of RSV, R3G and R4G for another 24 h, respectively. Panel A showed glucose uptake expressed as percentage of control in insulin-resistant HepG2 cells. Panel B showed glycogen content expressed as percentage of control. Panel C showed ROS levels expressed as mean fluorescence intensity. Values shown are means ± SD from three separate determinations. *p < 0.05; ^#p < 0.05 vs. only insulin-resistant HepG2 cells.