Protective effect of Insect tea primary leaf ( Malus sieboldii (Regal) Rehd.) extract on H 2 O 2 -induced oxidative damage in human embryonic kidney 293T cells

In this study, Insect tea primary leaf (Malus sieboldii (Regal) Rehd.) was used as the research object to investigate the protective effect of Insect tea primary extract (ITPLE) on hydrogen peroxide (H2O2)-induced oxidative damage in human embryonic kidney 293T cells (HEK 293T cells) and the mechanism of action of the main active components. The 3-(4,5-dimethyl-2-thiazolyl)- 2,5-diphenyl-2-H-tetrazolium bromide (MTT) assay was used to determine the toxicity of ITPLE to HEK 293T cells in vitro as well as its protective effect against (H2O2)-induced oxidative damage in HEK 293T cells. In addition, various assay kits were used to measure oxidation-related indicators in HEK 293T cells, and quantitative polymerase chain reaction (qPCR) analysis was used to determine the mRNA expression levels of oxidation-related genes in HEK 293T cells. High performance liquid chromatography (HPLC) analysis was used to characterize active components in ITPLE. The experimental results revealed that the ITPLE had no toxic effect on cells in the range of 0–200 μg/mL, and, in this range, exhibited a concentration-dependent protective effect against H2O2-induced oxidative damage in HEK 293T cells. It was also found that the ITPLE can reduce the malondialdehyde (MDA) level and increase the levels of superoxide dismutase (SOD), glutathione (GSH), glutathione peroxidase (GSH-Px), and catalase (CAT)in oxidative damage HEK 293T cells. The qPCR analysis results also showed that the ITPLE upregulated the mRNA expression levels of SOD, CAT, GSH and GSH-Px in HEK 293T cells damaged by H2O2-induced oxidative stress. The HPLC analysis identified 7 bioactive components in the ITPLE, including neochlorogenic acid, cryptochlorogenic acid, rutin, kaempferin, isochlorogenic acid B, isochlorogenic acid A and hesperidin. This study reveals that ITPLE is rich in active compounds and has good antioxidant effect in vitro, thus it has the potential to be developed into a traditional Chinese medicine and functional drinks.