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In this study,polysaccharide extracted from Morchella angusticepes Peck(PMEP)was chemically modified to obtain its carboxymethylated derivative(CPMEP).The physicochemical and cholesterol-lowering properties of PMEP and CPMEP were then comparatively investigated.The degree of substitution of CPMEP was 0.461.Fourier transform infrared spectra(FT-IR)analysis and 13C,1H,and DEPT135° NMR spectra indicated that C6 position was partially substituted by-CH2COOH.Results of scanning electron microscope and atomic force microscope indicated that the introduction of carboxymethyl group changed the structure of PMEP.Circular dichroism spectroscopy revealed the optical activity and conformation of CPMEP were different from that of PMEP.Moreover,serum total cholesterol of hypercholesterolemic rats treated with the high dose of PMEP and CPMEP was 1.54 mmol/L and 1.29 mmol/L compared with that of rats fed with 2%cholesterol diet(1.74 mmol/L),respectively,indicating CPMEP had a stronger cholesterol-lowering activity than PMEP.CPMEP had a trend in reducing liver total cholesterol while increasing the excretion of total fecal and intestinal bile acids,which were probably mediated by down-regulation of 3-hydroxy-3-methyl-glutarylcoenzyme A reductase(HMG-COA-R)while up-regulation of cholesterol-7α-hydroxylase(CYP7A1)in liver.It was therefore concluded that carboxymethylation of PMEP could enhance its cholesterol-lowering ability at least in rats model.