Structure Analysis Of Polysaccharides From Eight Types Of Bee Pollen And Their Antitumor Activities

Bee pollen is well known as dietary supplement and medicine, which has manybiological activities. Polysaccharides extrcted from bee pollen have many biological activities,including antivirus, antitumor, antioxidation and immunobiological activities. There are broadprospects for development of bee pollen polysaccharides. In order to gain more informationabout bee pollen polysaccharides and their structure-activity relationship, we fractionatedeight types of bee pollen polysaccharides including Papaver rhoeas, Rosa rugosa,Dendranthema indicun, Fagopyrum esculentum, Camellia japonica, Schisandra chinensis,Brassica campestris and Nelumbo nucifera. Total polysaccharides were extracted by hotwater and precipitated with ethanol and fractionted by ion-exchange chromatography. Thedifferences of structures among all fractions and the relationship of structure and anti-tumoractivity were also studied.The yields of eight types of bee pollen polysaccharides were from4%to11%. Therewere some differences about monosaccharide composition and structure features of bee pollenpolysaccharides. The best fractionation scheme about eight bee pollen polysaccharides wasachieved by DEAE-ion-exchange chromatography. One neutral fraction and two acidicfractions were obtained from each bee pollen polysaccharides. All the fractions were analysedby monosaccharide composition, total carbohydrate content, uronic acid content and mainstructure features. Eight bee pollen neutral fractions were mainly composed by glucose (Glc),galactose (Gal), arabinose (Ara) and mannose (Man). It suggested the existence ofarabinogalactan (AG) and glucan. The ratio of Ara and Gal was nearly1:1, contents of Glcwas different in eight bee pollen neutral polysaccharides. Little manoglucan was existed. Themolecular weights of neutral fractions were about1.0×10~4Da. The acidic fractions werepurified to0.2M and0.4M NaCl eluted fractions, respectively. These two fractions weremainly composed by rhamnose (Rha), galacturonic acid (GlcA), Gal and Ara, mainlycomposed of few type I rhamonogalacturonan (RG-I), homogalacturonan (HG) and largeportion of AG fragments. The0.4M NaCl eluted fraction had more RG-I and HG fragmentsthan0.2M NaCl eluted fraction.0.4M NaCl eluted fraction containd similar contents of RG-Iand AG fragments, HG region existed as small proportion.Bee pollen polysaccharides showed obvious antiproliferation activity on tumor cellsHCT116and HT29as dose-dependent way. Neutral fractions showed more significant inhibitactivity than acidic fractions. That may due to the different structure features, molecular weight and solubility of the sample. Neutral fractions were the main component in totalpolysaccharides which had the antitumor activity in vitro.The results of this paper can provide basic datas about structure-antitumor activityrelationship of polysaccharides.