Studv On The Chemical Constituents Of Dendrobium Heterocarpum Lindl And Lipid-lowering Activity Of Natural Products

This paper contained two parts,one was the study on chemical constituent of Dendrobium heterocarpum Lindl,another was the biological activity of phenolic compounds and D.heterocarpum.We made a summary about the machanism of antiobsity and the compounds with antiobesity activity in the first.Then all compounds were isolated by chromatography with silica gel,Sephadex LH-20,Diaion HP20SS and Lichroprep RP-18 gel and identified by spectral data;9 known compounds and 1 new compound were isolated from n-butanol extract of D.heterocarpum.Moreover by using preadipocyte(3T3-L1)to evaluate the proliferation activity of 9 compounds separation from D.heterocarpum and 21 phenol compounds,9 compounds were found to have the ability of inhibiting the proliferation of 3T3-L1 cell(p<0.05).Compound 23 could inhibit the proliferation of preadipocyte significantly(p<0.001).Then 9 compounds were used for further examination of 3T3-L1 differentiation ability.Unfortunately,no compounds have been found to block the differentiation of preadipocytes.Then we choose compound 23 to explore the mechanism of inhibiting proliferation activity of 3T3-L1 by using hoechest 33258 staining,annexin V-FITC/PI staining and western blot.Finally we found that compound 23 could induce apoptosis of 3T3-L1 cell and reduce the expression level of ERK1/2 protein.Then we tested the antiobesity and anti-hyperlipidemia activity of compound 21(mangiferin)by using C57BL/6J mice.Mangiferin was given to mice by oral administration at concentration 50 mg/kg/d and 200 mg/kg/d.At the end of the experiment,the relevant indexes(TC,TG,LDL-C,HDL-C,leptin)were detected.As a result,mangiferin could reduce the body weight of C57BL/6J mice and the levels of TC,LDL-C and expression of leptin in mice serum significantly(p<0.05).To explore the possible mechanism of antiobesity and anti-hyperlipidemia activity of mangiferin,3T3-L1 preadipocyte cell was treated further with mangiferin at doses ranging from 10μM to 60 μM to assess mangiferin s effects on protein ERK1/2.In addition,expression level of protein ERK1/2 in preadipocyte cell was reduced at 10 μM.These results suggested that mangiferin could prevent weight gain and hypolipidemic possibly by reducing the expression of leptin,TC,and LDL-C in mice serum in vivo and inhibiting expression level of protein phosphorylated ERK1/2 in preadipocyte in vitro.Finally,we made a summary of this article.