Hypoglycemic Effect Of Ginsenoside Compound K On Type2Diabetic Metlitus And Regulation Of Hepatic Gluconeogenesis

Generally, type2Diabetes mellitus (T2DM), one of most critical diseases, threatenshuman health in the world. Research hotspots, controlling fasting blood glucose andimprovement of insulin resistance for T2DM, has gained attention in recent years. Diabetesmellitus is namely Xiaokezheng, a disease with the symptom of frequent drinking andurination in traditional Chinense medicine. The main clinical manifestations of diabetes arethe symptoms of polydipsia, polyphagia, polyuria and thin body. This chronic disease needslong treatment. As for diabetes, in addition to drug treatment and getting rid of bad habits, itis necessary for diabetical patients to take functional food with little side effects. Currently,in order to improve life quality of DM patients, more and more researchers are seekingsupplementary treatment agents. Recently, many scientists are paying attention tosupplementary treatment agents with medicinal plant resources.Ginseng, the roots and rhizomas of Panax ginseng, is considered as the king of herbs. Inthe Shengnongbencaojing, ginseng was listed as the highest grade. It is worth mentioningthat ginseng as a treatment for DM and its complications drug caused great concern in thescientific community and gained considerable development. Modern pharmacologyconfirmed that Ginsenoside are the major active constituents and play a key role of treatmentof DM. Compound K, namely CK, M1and IH-901, was isolated from the metabolites ofhuman intestinal bacteria for the first time. CK was considered the final active substance ofthe PDG. The hypoglycemic effect of CK was increasingly attached researchers' attention.Previous studies have shown that CK was naturally found in ginseng flowers and berries,however, its content is only very few. Thus, given the similarity of the ginsenoside structureswith triterpenoid, CK can be obtained using biotransformation of panaxadiol-typeginsenosides (PDG). In this work, the authors employed snailase to bioconvert PDG toprepare ginsenoside CK. The influence factors of biotransformation were determined byusing response surface methodology (RSM). After ANOVA analysis, the optimum processparameters were determined as follows: enzymatical temperature of41°C, enzymatical loadof17.5%and enzymetical time of18h, pH value of4.5. Under the optimal conditions, thecontent of CK was14mg/mL. The experimental value is well in close agreement with the value predicted by the model. In conclusion, RSM method fully was applicable to theenzymatic conversion of preparation of CK.In this work, the therapeutic usefulness of CK and PDG in type2diabetical ICR mice, amore prevalent form of diabetes, was investigated for the first time. Type2diabetes wasinduced in male ICR mice by combining of streptozotocin. The male ICR mice fed withHFD for4weeks received100mg/kg of STZ injected intraperitoneally. After4weeks,diabetic mice processed symptoms of polydipsia, polyphagia, polyuria and thin body. CKtreatment at the30mg/kg/d doses was able to lower (p <0.05) fasting blood glucose levelsat week4. PDG treatment at300mg/kg/d dose also showed a significant effect on fastingblood glucose levels. Moreover, CK and PDG significantly (p <0.05) reduced TG and TClevels, respectively compared to diabetic control. In addition, treatment with CK led tosignificant increases in islet insulin content and the maximum insulin secretion capacity indiabetic mice and shown significant improvement in glucose tolerance after CK and PDGtreatment. Interestingly, CK work better than PDG on anti-diabetes. We think thathypoglycemic effect of PDG is partly responsible for CK action and CK is final active formof PDG.The main reason leading to T2DM is insulin resistance (IR) in peripheral tissue and therelative insufficience of insulin secretion. In other words, on one hand, the ability of fat andskeletal muscle loaded on glucose uptake was decreased. On the other hand, inhibition effectof hepatic gluconeogenesis weakened by insulin was weakened, which leading to excessivehepatic gluconeogenesis. Namely, insulin resistance can result in gluconeogenesis disorders.Recently, one of the most hot research fields for prevention and treatment of diseases of liverinsulin resistance has been to find herbal chemical constituents.According to statistics, about over50%of glucose consumption and the energy supply ofthe vital organs depending on gluconeogenesis. Hepatic gluconeogenesis as an importantpart of glucose metabolism plays a significant role. Factually, gluconeogenesis disorder isclosely related with diseases of insulin resistance, which can lead to diabetes, obesity,non-alcoholic fatty liver and other metabolic diseases. Inhibition of excessive hepaticgluconeogenesis and reducing of endogenous glucose production has been one of the moseimportant targets for treatment of T2DM and other metabolic diseases. As all we know,hepatic gluconeogenesis is regulated by a series of transcription factors including HNF4α,GR, PGC-1α and FOXO1. These transcription factors interacted with hormone andgluconeogenesis enzymes such as PEPCK and G6Pase, two key rate-limiting enzymes. The key point of their gene encoding crosstalk is to decide the start of gluconeogenesis.To date, hypoglycemic molecular mechanism of CK has been focused on insulin secretion.However, there is no report on hepatic gluconeogenesis of CK action. In this work, theauthors investigated the molecular mechanism of CK on HFD/STZ-induced ICR mice for thefirst time. Hypoglycemic effect of CK was mainly related to regulation of gluconeogenesissignaling pathway via activation of AMPK and suppression of PEPCK and G6Paseexpression.In the present study, the effect of CK on signaling pathway of liver gluconeogenesis wasinvestigated for the fisrt time. After injection of STZ for4weeks, protein expression ofG6Pase and PEPCK increased abnormally in type2diabetic mice. The result indicatedexcessive hepatic gluconeogenesis in diabetic mice. CK can suppress protein expression ofG6Pase and PEPCK after4-week treatment. Meanwhile, CK can also inhibit proteinexpression of PGC-1α. In addition, CK can inhibit glucose production with dose-dependentmaner on normal cultured HepG2hepatocytes. Compared with control, CK can inhibitprotein expression of G6Pase and PEPCK. Hypoglycemic effect of CK depends on hepaticgluconeogenesis via suppression of G6Pase, PEPCK and PGC-1α. At the least, anti-diabetesactivity of CK is partly by the regulation of hepatic gluconeogenesis signaling pathway.In the past years, AMP-activated protein kinase (AMPK), an important protein kinase, hasbecome one of most targets for the prevention and treatment of diabetes. The author detectedprotein expression of AMPK and p-AMPK in the livers of diabetic mice induced byHFD/STZ. The results indicated that STZ injection after8week, the activity of AMPK indiabetial mice was inhibited significantly. After CK treatment for4weeks, CK can activateAMPK and enhance the ratio of p-AMPK/AMPK in liver tissues. Experiment on HepG2hepatocytes in vitro indicated that CK and AICAR (an AMPK activator) can activate AMPKin normal HepG2hepatocytes. Meanwhile, Compound C (an AMPK inhibitor) can inhibitactivity of AMPK and the activation of CK was partly reversed by Compound C. In addition,CK can also suppress protein expression of the key nuclear factors including PGC-1α,FOXO1and HNF4α, and these inhibition effect was decreased in the presence of CompoundC. From the experiments in vivo and in vitro, suppression of hepatic gluconeogenesis waspartly related to activation of AMPK signaling pathway.In a word, we employed RSM to optimize snailase preparation of ginsenoside CK fromPDG. The optimum biotransformation condition was obtained via model construction. PDGand CK can lower fasting blood glucose and TG and TC level on type2diabetic mice induced by HFD/STZ. In addition, CK and PDG can improve glucose tolerance and insulinresistance, and enhance insulin sensitivity index. What's more, CK can activate AMPKactivity and inhibit protein expression of G6Pase, PEPCK, FOXO1, PGC-1α, and HNF4α.Excessive hepatic gluconeogenesis was inhibited and endogenous glucose production waslowered. Hypoglycemic effect of ginsenoside Compound K on T2MD was partly related tosuppression of hepatic gluconeogenesis via regulation of AMPK/PEPCK/G6Pase signalingpathway.