Effects Of Lycium Barbarum L.Leaves Flavonoid Extract On Lipid Metabolism Of HepG2 Cells And Microcapsule Preparation

In recent years,the incidence of obesity and hyperlipidemia in China has shown an increasing trend,which seriously threatens people’s health.Lycium barbarum L.Leaves flavonoids(LBLF)are a natural flavonoid compound with a variety of biological activities and great potential for development in lowering lipids and blood sugar.However,LBLF is unstable and susceptible to oxidative decomposition due to temperature,light,food additives and other factors.In this paper,LBLF extract was used as the research object,and the experimental results were as follows:To investigate the effect of LBLF extract on oleic acid(OA)-induced lipid accumulation in HepG2 cells.HepG2 cell viability was determined by CCK-8 experiment,0.4 mM OA was selected for HepG2 cells to be treated for 24 h,and LBLF extract concentration of 40～250 μg/mL had no significant effect on HepG2 cell viability(P>0.05),based on practical considerations,LBLF extracts were selected at doses of 40,60,80 μg/mL to treat HepG2 cells for 24 h,and 0.4 mM orlistat was selected to treat HepG2 cells for 24 h.Compared with the blank control group,it was found that lipid droplet aggregation decreased with the increase of LBLF extract dose.Compared with the model control group,the contents of intracellular triglycerides(TG),total cholesterol(TC),and low-density lipoprotein(LDL-C)decreased,while the content of high-density lipoprotein(HDL-C)increased significantly.Compared with the model control group,the levels of oxidative stress in HepG2 cells after OA induction LBLF extract treatment were significantly upregulated and the contents of malondialdehyde(MDA)(P<0.01)were significantly upregulated compared with the model control group.Fluorescence microscopy showed that the content of reactive oxygen species(ROS)in HepG2 cells was significantly reduced compared with the model control group(P<0.01),indicating that LBLF extract improved the oxidative stress response of OAinduced HepG2 cells.Real-time quantitative PCR(qPCR)and Western blot detected the expression of mRNA levels and protein levels of key genes related to lipid production,and LBLF extracts can reduce OA-induced lipid metabolism disorders in HepG2 cells by regulating the downregulation of SREBP-lc,PPARy,CEBPα,ACC,FAS,SCD-1 levels and upregulation of p-AMPK/AMPK levels.To prepare Lycium barbarum L.leaves flavonoids microencapsulation(M-LBLF)using gelatin and sodium carboxymethylcellulose(CMC)as wall materials.The experimental results show that the optimal wall ratio of gelatin and CMC is 9:1(w/w)and the optimal pH is 4.5 by measuring the zeta potential,turbidity curve,emulsification stability and emulsification activity index.The optimal process ratio obtained from the response surface software is:wall material concentration 1.15%,core-to-wall ratio 1:3.86,stirring temperature 45.09℃,and the highest embedding rate is 84.51%.From the scanning electron microscopy,it can be seen that most of the surface is smooth,the structure of the capsule wall remains intact,it is a rough and dense structure that is closely connected,and the prepared microcapsule particle structure has no obvious cracks,and the wall material has not been ruptured.Fourier infrared scanning showed that in the M-LBLF spectrum,the presence of a characteristic peak at 1578 cm-1 may be an offset of C=O at 1594 cm-1 in LBLF,and an absorption peak at 1422 cm-1 shifted to a lower wavenumber,possibly due to electrostatic interaction at CMC.The diffraction peak positions of M-LBLF and LBLF are basically the same,but there is a slight change in peak intensity,and the intensity of the diffraction peak at(2θ)20° is enhanced,which may be due to microencapsulation and partial transformation of the amorphous structure into a crystalline state.The thermogravimetric analysis found that microencapsulation delayed the pyrolysis of LBLF extract and played a protective role.LBLF extract and M-LBLF were simulated in vitro digestion,and it was found that the release amount of the intestinal digestion stage was higher than that in the gastric digestion stage,which may be caused by hydrolysis of phenols in the weak alkaline environment of intestinal digestion stage,and the results of in vitro simulated digestion showed that microencapsulation improved antioxidant activity.M-LBLF can inhibit pancreatic lipase and α-amylase,and the type of inhibition is non-competitive inhibition.