Structure Identification and Hypoglycemic Activity of Polysaccharides from Mulberry Leaves
Objective To elucidate the structural basis of polysaccharides with hypoglycemic activity in mulberry leaves,and provide a theoretical basis for the development and utilization of mulberry leaves.Methods The crude polysaccharides from mulberry leaves were extracted by hot water.The components of SY02,SY02-3,SY02-3A and SY02-3B were obtained by ion-exchange chromatography and gel permeation chromatography.We determined the physicochemical properties of homogeneous polysaccharide.The structure of mulberry leaf polysaccharide was identified by monosaccharide composition analysis,sugar residue linkage analysis and nuclear magnetic analysis.Palimitate(PA)induced INS-1 cell apoptosis model was used to determine the protective effect of mulberry leaf polysaccharide on INS-1E cell apoptosis,and Caspase3/7 activity kit was used to detect mulberry leaf polysaccharide on the key protein of INS-1E cell apoptosis Cleaved by Western blot method effect of Caspase 3 expression.Results The crude polysaccharide SY was extracted from mulberry leaves by hot water,which was separated by ion exchange resin column and purified by gel column to obtain SY02-3.After purification,we obtained homogeneous polysaccharide SY02-3A and proteoglycan SY02-3B,with molecular weights of 3.7×104 Da and 1.03×104 Da.The results of monosaccharide composition analysis showed that SY02-3A contained rhamnose,galacturonic acid,galactose,xylose and arabinose.The molar ratio of SY02-3A was 23.97:33.85:11.73:5.04:25.41,and the yield was 0.32%.SY02-3B is composed of rhamnose,galacturonic acid,glucose,galactose and arabinose.The molar ratio of SY02-3B is 19.83:10.34:45.42:9.01:2.23:13.17 with a yield of 2.00%.SY02-3B contains 14 amino acids,among which the content of aspartate,glutamic acid,alanine and glycine is relatively high.We also found that SY02-3 protects palmitic acid-induced INS-1E cell apoptosis,which may be associated with reduced Caspase 3 activity and down-regulated cleaved Caspase 3 protein expression.Conclusion Mulberry leaf polysaccharide SY02-3,which contains acid peptidoglycan(SY02-3A)and proteoglycan(SY02-3B)in mulberry leaves,has the effect of inhibiting PA-induced apoptosis of INS-1E cells.
NETL
NSTL
万方数据
