| Lycium barbarum is a kind of famous traditional Chinese medicine and food plants,mainly growing in northwestern China.Modern pharmacological studies have shown that polysaccharides are one of the most important active ingredients in the fruit of Lycium barbarum.Traditional separation and purification method of Lycium barbarum polysaccharides is column chromatography,which is complicated with low yield and some polysaccharides fractions loss.The research on the activity of Lycium barbarum polysaccharides mainly focuses on the crude polysaccharides,which is difficult to determine the most important active ingredients and study the structure-activity relationship.Lycium barbarum polysaccharides were firstly separated and purified by fractional precipitation.All Lycium barbarum fractions were obtained,which could comprehensively study physicochemical properties and biological activities of Lycium barbarum polysaccharide fractions.Our results could lay the foundation for further comprehensively study on structure-activity relationship of Lycium barbarum polysaccharides,and provide a scientific basis for the comprehensive development and utilization of Lycium barbarum.The results were as follows:1.The crude polysaccharides(LBP)were obtained by water extraction,alcohol precipitation,deproteinization,and freeze-drying.The retentate LBP-I and dialysate LBP-O were obtained from LBP with dialysis(8-14 kDa MWCO).LBP-I was separated by fractional precipitation and three fractions(LBP-I-1,LBP-I-2 and LBP-I-3)were obtained.The three fractions were further purified by molecular sieve column chromatography to LBGP-I-1,LBGP-I-2 and LBGP-I-3,respectively.2.The physicochemical properties of Lycium barbarum polysaccharide fractions were characterizated based on gas chromatography,high performance gel permeation chromatography and infrared spectroscopy.The results showed that LBP-O mainly consists of glucose(72.8%);LBGP-I-1(3.19×104 Da)mainly consists of arabinose(21.95%),glucose(51.22%)and galactose(17.07%);LBGP-I-2(2.92×104 Da)mainly consists of arabinose(19.35%),glucose(32.26%)and galactose(35.48%);LBGP-I-3(9.12×104 Da)mainly consists of arabinose(48.15%)and galactose(44.44%),belong to arabinogalactan.The sugar content using phenol-sulfuric acid method was 71.56%,36.23%,55.52%,and 81.42%,spectively.The protein content using Bradford method 56%,60.54%,40.1%,and 18.5%respectively.3.The antioxidant activity of Lycium barbarum polysaccharide fractions was evaluted by reducing power,free radical scavenging ability and inhibition H2O2-induced HepG2 injury in vitro.The LBP-O showed the strongest antioxidant activity,the reduce power,DPPH-scavenging ability and O2-·scavenging ability were 1.23,95.34%and 74.65%,respectively.The viability of H2O2-induced HepG2 cell treated with LBP-O was 96.32%,which showed that the LBP-O was the most active ingredient of anti-oxidation.4.The immune activity of Lycium barbarum polysaccharide fractions was evaluated using splenic lymphocytes and macrophage RAW264.7.The results showed that the Lycium barbarum polysaccharide fractions have different immunoregulatory ability.The arabinogalactan showed strongest effect on spleen lymphocyte proliferation,LPS or ConA induced splenic lymphocyte proliferation and the splenic lymphocyte proliferation,proliferation index were 1.56,1.94,2.3,respectively.The arabinogalactan showed the strongest effect on RAW246.7 phagocytosis capacity(1.9),acid phosphatase activity(1.55)and NO production(22.85?M),which showed the arabinogalactan was the most active ingredient of immunoregulatory.5.Arabinogalactan showed the strongest inhibition on cancer cell growth.The inhibition rate of arabinogalactan on MCF-7 was 53.21%.Further studies on the mechanism of arabinogalactan inhibiting the growth of MCF-7 showed that arabinogalactan could induce MCF-7 cell apoptosis and arrest cell cycle in the G0/G1 phase,which could mediate MAPKs signaling pathways. |
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