Preliminary Investigation Of Phenylpropanoid Glycoside From Ligustrum Purpurasens To Effect Lipid Digestion And Metabolism

Obesity is a major threat to public health,which may cause many diseases such as heart disease,cancer,atherosclerosis,diabetes,etc.In recent years,screening natural drugs for losing weight from Chinese herb have attracted great interest.In this study,we investigated phenylpropanoid glycoside(PPGs),the predominant content in Ligustrum Purpurasences,for its inhibition for lipase in vitro and lipid metabolism in 3T3-L1 preadipocyte cell.We selected total PPGs and 4 major constituents of PPGs(Acteoside,lipedoside A-I,syringaride A 3’-α-L-rhamnopyranoside and osmanthuside B,which share the same skeleton but have different numbers of hydroxyl groups on the A-or B-ring)on inhibiting the activity of lipase in vitro.We used fluorescence spectroscopy,circular dichroism(CD),high-performance liquid chromatography(HPLC)and docking studies to help explore the inhibition property of PPGs.At the cellular level,Act was used to treat 3T3-L1 cells at cell proliferation and differentiation progresses.The cell viability was detected by CCK8 method and the lipid accumulation was observed by oil O staining and intracellular triglyceride assay.The absorption of free fatty acid was detected by fluorescence method.Moreover,the changes in the expression of proteins associated with adipocyte differentiation in 3T3-L1 cells were measured.The main results are as follows:1,The activity of PPGs was related to the number and the positions of the phenolic hydroxyl groups.The activity of phenolic hydroxyl on B-ring was stronger than that on A-ring.The order of inhibition on lipase activity was Act> Lip> Syr> Osman B.The results of CD and fluorescence showed that four kinds of components above could loose the structure of lipase.According to the results of HPLC experiments,the more phenolic hydroxyl groups were existed on the components,the stronger affinity was presented between the lipase and the components,the better inhibition was showed on lipase.2,The results of CCK8 showed that Act could decrease the viability of non-confluent 3T3-L1 cells,while Act had no obvious toxicity to mature adipocytes and the cells undergoing differentiation.Oil red O staining and triglyceride assay indicated that when cells were treated with 1 μM,10 μM and 100 μM Act for 7 days during adipocyte differentiation,the content of intracellular triglycerides was decreased to 83.01%,78.33% and 76.07%,respectively.For the mature adipocyte,however,1 μM Act only caused a smaller effect.The content of triglyceride was reduced to 94.57% and 70.60%,after the treatment of 10 μM and 100 μM Act for 24 h,respectively.The fatty acid uptaking experiment revealed significantly differences only when the the cells were treated for over 18 h.When the cells were treated with 1 μM,10 μM and 100 μM Act for 18 h,the capacity of free fatty acid uptaking were decreased to 90.27%,80.69%,83.19%,respectively compared with control adipocytes.3,For differentiating 3T3-L1 cells,Act significantly decreased the expression of the key adipocyte differentiation regulator PPAR-γ and adipocyte-specific proteins such as FASN and a P2.For differentiated mature adipocytes,Act significantly reduced the expression of FASN and PPAR-γ but did not show significant effect on the expression of a P2.