ROS production induced by
nicotine was attenuated by RES treatment in a dose-dependent
manner, decreasing down to 8.3% at the highest concentration
(250 μM) compared to nicotine only (Figure 3A). Significant inhibition
in ROS production with increasing amount of OXY was
observed, ranging from 2.7% to 8.3% (Figure 3B). ROS scavenging
capacity in combinational treatment of RES and OXY
was stronger than those of individual pretreatment of RES or
OXY (Figure 3C). EESC rich in RES and OXY remarkably decreased
ROS production induced by nicotine by 11% compared
with those of the control (Figure 3D). In addition, ROS scavenging
effect of EESC was significantly higher than those of RES,
OXY, and RES+OXY pretreatment. These results suggest that the
combinational treatment of RES and OXY or EESC enhanced
the ability of individual component to reduce ROS production induced by nicotine in HepG2 cells. In addition, it is possible
that EESC could have other low molecular weight of phenolic
compounds that can be detected by GC-MS rather than LC-MS,
possibly resulting in reduction of ROS induced by nicotine.