Paeonin extracted from potatoes protects gastric epithelial cells from H 2 O 2 -induced oxidative damage in vitro by PI3K/Akt-mediated Nrf2 signaling pathway

In this study, it is aimed to investigate the antioxidant mechanism of new extracts from potatoes. Four pigments, namely, Petunin, Paeonin, Malvidin and Pelargonidin, were extracted from potatoes by high performance liquid chromatography (HPLC). Our results showed that the cellular morphology and cell viability were significantly altered in gastric mucosal epithelial cells (GES-1) treated with different hydrogen peroxide (H 2 O 2 ) concentrations over time ( P < 0.05). Paeonin presented the strongest anti-oxidative effects on H 2 O 2 -treated cells, in both a dose- and time-dependent manner, determined by ARE-luciferase activity and HO-1 mRNA expression. After pre-treatment with Paeonin in H 2 O 2 -exposed cells, Keap1, Nrf2, HO-1 and NQO1 protein expressions were remarkably up-regulated. Furthermore, immunostaining of Nrf2 expression was obviously elevated in the H 2 O 2 + Paeonin group over time. The GSH content in the H 2 O 2 + Paeonin group was notably lower than that in the H 2 O 2 + Paeonin + GSK690693 group. Paeonin promoted cell cycle with augmented Cyclin D1 and p27 protein expressions. Moreover, Paeonin suppressed apoptosis with increased Bcl2, total Caspase3 and total Caspase8 protein expressions and decreased Bax, p-Caspase3 and p-Caspase8 protein expression in H 2 O 2 -treated cells. These results suggested that Paeonin might exert an anti-oxidative role by activating Nrf2 signaling pathway with the changes of cell cycle and apoptosis.