Improvement of Flavonoids in Lemon Seeds on Oxidative Damage of Human Embryonic Kidney 293T Cells Induced by H(2)O(2)

In this study, flavonoids in lemon seeds (FLS) were used to assess its improvement on the oxidative damage of human embryonic kidney 293T cells (HEK 293T cells) induced by H(2)O(2). In vitro experiments showed that the survival rates of HEK 293T cells treated with different flavonoid concentrations (50 μg/mL, 100 μg/mL, and 150 μg/mL) exceeded 95%, indicating no significant toxic effect. Compared with the normal group, H(2)O(2) (0.3 mmol/L) resulted significantly in oxidative stress injury of HEK 293T cells. The survival rate of the damaged cells increased after treatment with flavonoids, and the survival rate of cells treated with a high concentration (150 μg/mL) of flavonoids was 76.2%. Flavonoids also effectively inhibited H(2)O(2)-induced apoptosis. At the same time, flavonoid treatment significantly reduced the malondialdehyde content in cells and increased the levels of catalase (CAT), superoxide dismutase (SOD), glutathione (GSH), and glutathione peroxidase (GSH-Px). Quantitative polymerase chain reaction (qPCR) and Western blot analysis also suggested that FLS upregulated mRNA and protein expressions of CAT, SOD (SOD1, SOD2), GSH (GSH1), and GSH-Px in H(2)O(2)-induced oxidative damage of HEK 293T cells. The high-performance liquid chromatography analysis demonstrated that FLS contained six compounds, including gallocatechin, caffeic acid, epicatechin, vitexin, quercetin, and hesperidin. FLS were proven to have a good antioxidant capacity in vitro and improve significantly the oxidative damage of HEK 293T cells induced by H(2)O(2). The biological activity value warrants investigation in additional studies.