Preparation And Application Of Sulfated Konjac Glucomannan

The konjac has2,000years of cultivation history in China. Konjac glucomannan(KGM) are existed in tubers of konjac as a reserve polysaccharide. KGM has excellenthydrophilicity, thickening, rheology, reversibility, suspension, and other characteristics,and is widely used. The sulfated KGM (SKGM) increases its anticoagulant, anti-virusactivity and takes more and more attention. SKGM contains a lot of hydroxyl groupsand sulfuric acid groups. In theory, they can form hydrogen bonds, ionic bond orcoordination bond with neighboring molecules. The results, obtained in this subject, canelaborate the chemical mechanism of the intermolecule from the molecular level. Thisstudy may guide SKGM more application research and show a clear value.The commercially available konjac powder was purified and the impurities wereremoved by ethanol precipitation. The purity of KGM is98.63%. The viscosity averagemolecular weight of KGM was1.79million. KGM consisted of two components, themolecular weight of them were1.18million and2million, respectively. Because of itslarge molecular weight and neat arrangement, the viscosity of KGM aqueous solutionwas high and the viscosity was increased with the increasing of molecular weight.KGM had a lot of hydroxyl groups and β-1,4Glycosidic bond. With thechlorosulfonic acid, the hydroxyl oxygens were the electron-donating group and prone toelectrophilic substitution reaction. The hydrogen of hydroxyl groups was easy to besubstituted by-SO3H to get SKGM under certain conditions. The optimal conditions forsulfating ware following: the ratio of KGM: chlorosulfonic acid was0.5g:6mL.Thereaction was in3h at70°C, and the degree of substitution was1.053. And on the otherhand, the hydrolysis of β-1,4Glycosidic bond was occurred with strong acid. themolecular weight of SKGM was reduced to87thousand because of the hydrolysis. Thedecreases of the molecular weight directly caused the viscosity decreases to63mpa/s.Viscosity was used to be the indicator to research the main influencing factors ofinteraction between SKGM and biological macromolecules were ion concentration,temperature and pH. The atomic force microscope was provided a direct evidence toprove that SKGM and XG complex formed spatial mesh structure through hydrogenbonds.