Preparation And Properties Of Modified Konjac Glucomannan Sulfates

As a native recource, konjac is chiefly grown in our country and widely used in the food and medicine industry. The main active ingredient of konac is the konjac glucomannan (KGM), which enjoys the excellent biocompatibility, biodegradation and non-toxic. At present, many investigators have become interested in KGM. KGM is a β3-(1â†'4) linked polysaccharide composed of a D-glucosyl and D-mannosyl backbone lightly branched, possibly through β-(1â†'3) glucosyl units. KGM is a high molecular weight native polymer and its molecular weight (Mw) ranges from200to2000kDa. In this work, the sulfates of modified KGM were prepared by biological and chemical modifications. The anticoagulant activities of sulfates of modified KGM were also investigated as a heparin substitute.The main contents and conclusions are summarized as below:(1) The KGM samples with different molecular parameters were prepared by cellulose in aqueous solution. And then the konjac glucomannan sulfates (KGMS) with different Mw and degree of substitution of sulfate (DS) were synthesized by KGM samples with trisulfonated sodium amine in aqueous solution. The prepared KGMS sample of DS value can reach1.30and the Mw were range from2x104to1.54x106. The anticoagulant results of KGMS indicated that the best Mw was1.2X105In addition, increase the concentration and DS increased the anticoagulant activities.(2) The carboxymethyl konjac glucomannan (CKGM) was produced by chloroacetic acid and KGM in aqueous solution. And then carboxymethyl konjac glucomannan sulfates (CKGMS) were synthesized by CKGM samples with trisulfonated sodium amine in aqueous solution. The reaction conditions of CKGMS were optimized. The optimal conditions were found to be as follows:the pH of the reaction medium, the reaction temperature, the reaction time, and the ratio of the mole of sodium nitrite to the mass of CKGM were8.0,50℃,12h and2.5/200(mol/g), respectively. The analysis results of13C NMR suggested that the sulfate position of were possible on the C2, C3and C6of CKGM molecular unit. The anticoagulant results of CKGMS indicated that the best Mw was2.48x105In addition, increase the concentration and DS increased the anticoagulant activities.(3) The konjac glucomannan quaternary ammonium salt (QKGM) sample was prepared in the presence of3-chloro-2-hydroxypropyl trimethyl ammonium chloride (CHPTAC) in aqueous solution. After that, the konjac glucomannan quaternary ammonium salt sulfates (QKGMS) were synthesized by QKGM samples with trisulfonated sodium amine in aqueous solution. The optimal conditions were found to be as follows:the pH of the reaction medium, the reaction temperature, the reaction time, and the ratio of the mole of sodium nitrite to the mass of QKGM were8.0,60℃,8h and2.5/230(mol/g), respectively. The analysis results of13C NMR suggested that the sulfate position of QKGMS were possible at the C2, C3and C6of QKGM molecular unit. The anticoagulant results of QKGMS indicated that the best Mw was1.98×105and best concentration was60ug/mL. In addition, increase the DS increased the anticoagulant activity.The main creative points are listed as following:(1) As a sulfating reagent, trisulfonated sodium amine can overcome the drawbacks of traditional sulfating reagent in highlyacid, high pollution and toxic. In this work, CKGMS and QKGMS were prepared for the first time. The sulfate reaction was carried out in aqueous solution so that avoid introducing organic reagents.(2) The relationship of between modified KGM sulfates and anticoagulant activities were investigated systematically. The clotting time suggested that the anticoagulant activities of modified KGM sulfates depended on the concentration, Mw and DS.