Comparison Of Oxidative Stress Damage Of HepG2 Cells Between Phlorizin And Phloretin

Phlorizin and phloretin are flavonoids with dihydrochalcone structures.They have many biological activities,such as regulating blood glucose levels,antioxidant,anti-inflammatory,anti-cancer activities and so on.The chemical structure of phlorizin possesses one more glucoside than that of phloretin,which might makes the biological activities of phloretin differ from that of phlorizin.In the present study,the human hepatoma cell line(HepG2)model was established to evaluate the antioxidant activities of phlorizin and phloretin in vitro and the molecular mechanism of their effects was investigated.It is important for rational utilization of phlorizin and phloretin.In this study.MTT method was used to detect the effect of phlorizin,phloretin and oleic acid on the cell viability of HepG2 cells and oleic acid oxidative model was established.Intracellular ROS accumulation was evaluated by DCFH-DA fluorescent probe,and the GSH content in cell was determined by the MCB fluorescent probe.The antioxidant enzymes were determined using the related kits.The comet assay was conducted to detect the nuclear DNA damage,furthermore,cell apoptosis was detected by flow cytometry.The mRNA expression level of related antioxidative genes was determined by RT-PCR.The docking experiment was performed using AutoDock 4.2.6 to study the interaction between two compounds of phlorizin and phloretin and Nrf2 protein.The results showed that phlorizin and phloretin could significantly reduce ROS level,increase GSH content,increase antioxidant enzyme activity and decrease MDA content induced by oleic acid in cells as model objects,which illustrated that the oleic acid-induced oxidative damage model was successfully constructed,confirming that phlorizin and phloretin possess significant antioxidant effect.A certain dose of phlorizin and phloretin could alleviate DNA damage in nucleus and reduce the total apoptotic rate of cells.The genes expression levels of Nrf2,HO-1 in phlorizin and phloretin groups were up-regulated,suggesting that a certain dose of phlorizin and phloretin could activate the transduction of Nrf2/HO-1 oxidative damage pathway.The up-regulation of other antioxidant related genes such as CnZn-SOD,Mn-SOD,GCLC,GCLM,GSS and GSR in the phlorizin and phloretin groups confir-med the protective effect of phlorizin and phloretin on oxidative damage of cells.According to the results of molecular docking,the binding conformation energy of phloretin and Nrf2 was lower than that of phlorizin,that is,the structure is more stable,inferring that phloretin has better antioxidant effect in Nrf2 signaling pathway.It can be seen from the comparison of the effects of two substances that the protective effect of phloretin on oleic acid-induced oxidative damage of cells is more significant than phlorizin,that is to say.phloretin possesses stronger antioxidant capacity.