Hypoglycemic Mechanisms Of Polyphenol-rich Vinegar Extract In Insulin-resistant Cells

With the improvement of people’s living standards,the morbidity of diabetes mellitus(DM)is increasing year by year,and insulin resistance has attracted much attention as an important pathogenesis of DM.At present,exercise and diet are important means to prevent DM,and polyphenols in plants and food provide effective strategy for the prevention of DM.Vinegar is rich in polyphenols and has antioxidant activity.In this study,we investigated the hypoglycemic effects and molecular mechanisms of Zhenjiang aromatic vinegar extract(ZAVE)on high glucose induced insulin resistant Hep G2 cells.Firstly,polyphenols of ZAVE were extracted with ZAV and ethanol at a volume ratio of 1:2.The results of in vitro antioxidant activity assay showed that the antioxidant activity values of ZAVE were 31.576 ± 2.573 m M Trolox/L(ABTS assay),39.173 ± 1.288 m M Trolox/L(DPPH assay)and 22.141 ± 1.030 m M Trolox/L(FRAP assay),respectively.The antioxidant activity of ZAVE was higher than that of ZAV.8 and 21 polyphenols were detected in ZAVE by HPLC and GC-MS,respectively.Secondly,high glucose-induced insulin resistant model of Hep G2 cells was established.Cell viability was detected by CCK-8 method,and the results showed that ZAVE had no tonic effect on Hep G2 cells at low concentration(100-400 μg/m L).Therefore,ZAVE concentration of 100-400 μg/m L was selected for subsequent experiments.Kits assay showed that ZAVE could increase glucose consumption and glycogen synthesis,and reduce glucose production.The hypoglycemic effect of 400 μg/m L ZAVE was better than other concentrations of ZAVE.The fluorescent probe 2-NBDG was used to detected that ZAVE could enhance glucose uptake.The results showed that ZAVE has a hypoglycemic effect on Hep G2 cells induced by high glucose.Finally,ZAVE inhibited ROS generation in cells were measured by fluorescent probe DCFH-DA.ZAVE inhibited the expressions of JNK and IRS-1 proteins,and increased the the expressions of PI3 K and Akt proteins in cells were detected by Western blot.The results showed that ZAVE could activate JNK-mediated glucose metabolism signaling pathway.In addition,insulin resistant cells were treated with ZAVE alone or in combination with the JNK inhibitor SP600125.Western blot measured showed that ZAVE down-regulated the expressions of JNK,IRS-1,and GS proteins,and up-regulated the expression of GSK3β protein.RT-q PCR detected showed that ZAVE inhibited the m RNA expressions of G6 Pase and PEPCK.The results showed that ZAVE could inhibit the JNK/IRS-1 signaling pathway and further activate the PI3K/Akt signaling pathway to exerts hypoglycemic effect on high glucose induced insulin resistant Hep G2 cells.The results of study indicate that ZAVE is rich in polyphenols and has strong antioxidant activity,and exerts a hypoglycemic effect on insulin resistant Hep G2 cells by activating IRS-1/PI3K/Akt signaling pathway.The results will provide theoretical basis and ideas for the research of polyphenols to prevent DM,which has important clinical significance and application value.