Study On The Differences And Mechanisms Of Hypoglycemic Effects Of Sesamol And Sesamin In Sesame Oil In Vitro

Sesame lignans are special lipid components in sesame oil,mainly including sesamol and sesamin.In recent years,sesamol and sesamin can inhibit the activity ofα-glucosidase and have the effect of improving the blood sugar level and insulin resistance in rat.However,the differences between sesamol and sesamin and their corrresponding specific mechanism of actions remaind to be further studied.Therefore,this paper first used meta-analysis to confirm that sesamol and sesamin in sesame lignans had significant hypoglycemic effects.Subsequently,the in vitro inhibition ofα-glucosidase model and Hep G2 cell insulin resistance model were used to systematically explore the hypoglycemic effects and related mechanisms of sesamol and sesamin.Finally,the improvement effect of sesame oil containing the above two active substances on insulin resistance was evaluated.The main research content and results of this paper were as follows:Firstly,systematic review and meta-analysis were used to summarize and analyze the data from animal studies,and then to explore the effect of sesame lignans on diabetes.The results of meta-analysis showed that sesamol and sesamin in sesame lignans had an effect on the blood glucose[SMD=-3.58（-4.55,-2.60）,P<0.00001;SMD=-2.59（-3.80,-1.39）,P<0.0001],serum total cholesterol[SMD=-2.39（-3.10,-1.68）,P<0.00001;SMD=-3.10（-5.14,-1.06）,P=0.003]and serum triglycerides[SMD=-3.06（-4.03,-2.10）,P<0.00001;SMD=-1.80（-2.65,-0.96）,P<0.0001].All results suggested that sesamol and sesamin could significant improve the diabetes.Secondly,the inhibitory effect of sesamol and sesamin onα-glucosidase and its related mechanisms were investigated.The results showed that both sesamol and sesamin were non-competitive inhibitors ofα-glucosidase with IC₅₀ values of 0.96 m M and 0.33 m M,respectively,and inhibition constants K_i values were 4.02×10^-3 mol/L and 1.48×10^-3 mol/L,respectively.The results of fluorescence spectra and thermodynamic indicated that both sesamol and sesamin quenched their fluorescence by static quenching mechanism.TheirΔG°<0,indicated that their binding toα-glucosidase occurred spontaneously.TheΔH°andΔS°values of sesamol and sesamin were-9.94 k J·mol^-1,-37.86 k J·mol^-1 and 36.23 J·mol^-1·K^-1,-52.40 J·mol^-1·K^-1,respectively.The results showed that the main forces among sesamol and sesamin and enzymes were hydrogen bond,hydrophobic interaction and van der Waals force,hydrogen bond,respectively.The results of synchronous fluorescence,three-dimensional fluorescence and circular dichroism spectroscopy indicated that both sesamol and sesamin could change the conformation ofα-glucosidase.The results of molecular docking showed that sesamol formed hydrogen bonds with residues ASP-242 and SER-241,while sesamin formed hydrogen bonds with residues LYS-16,SER-298 and THR-274.The above results indicated that sesamol and sesamin had the potential asα-glucosidase inhibitors,and the effect of sesamin was better than that of sesamol,which may be caused by their different structures and their different binding sites withα-glucosidase.Thirdly,the improvement effect of sesamol and sesamin on insulin resistance was investigated by establishing an in vitro cellular insulin resistance model.The results showed that compared to the model group,the glucose consumption levels of IR-Hep G2 cells were increased by 29.21%and 56.42%（P<0.05）and glycogen levels were increased by 15.47%and 54.75%（P<0.05）after the intervention of sesamol and sesamin,respectively.Meanwhile,both sesamol and sesamin inhibited the activity of G6Pase and PEPCK,the key enzymes for gluconeogenesis.Sesamol and sesamin could reduce G6Pase enzyme activity by 24.35%and28.17%（P<0.05）,and reduced PEPCK enzyme activity by 15.05%and 25.23%（P<0.05）,respectively,when comparing with the model group.In addition,the gene expression levels of PI3K,AKT,INSR and IRS-1 increased in IR-Hep G2 cells treated with sesamol and sesamin,so it is proposed that sesamol and sesamin may regulate glucose metabolism in Hep G2 cells by activating the PI3K/AKT signaling pathway.Finally,we evaluated the effects of sesame oil containing the above two active substances on insulin resistance by IR-Hep G2 cells.The results showed that after treating with sesame oil and reverse addition of sesame oil,the glucose consumption of the cells was increased by 75.90%and 62.32%（P<0.05）,and the glycogen content levels recovered to8.21±0.19μg/mg pro and 7.19±0.14μg/mg pro,respectively,compared to the model group.The above results showed that sesame oil containing sesamol and sesamin also had an improved effect on insulin resistance.In conclusion,this study systematically elucidated the in vitro hypoglycemic mechanisms of sesamol and sesamin from two hypoglycemic dimensions:reducing blood glucose production to delay carbohydrate digestion and absorption and increasing the route of blood glucose to improve insulin resistance,which could lay a theoretical foundation for their subsequent use as potential hypoglycemic natural substances,as well as being of great significance for improving the application range of sesame lignans.