| Konjac glucomannan(KGM)is a high molecular weight watersoluble non-ionic(neutral)polysaccharide composed of ?-D-glucose and ?-D-mannose by the linkage of ?-1,4 glycosidic bonds.It has been proved that KGM has several biological func-tions,such as hypoglycemia,lipid-lowering,anti-tumor,anti-virus and so on.This thesis mainly investigated the physical properties,chemical properties and structure of konjac glucomannan short-chain molecule(KGSM),and then further tested its hypo-glycemic and hypocholestrolemic activities in vitro.The result of this thesis may provide a theoretical basis for the study of structure-activity relationship of KGM.In this study,60Co ?-ray irradiation and hydrogen peroxide were utilized in prepara-tion of KGSM.The molecular weight(Mw)and polydispersity index(PDI)of samples were detected by a gel permeation chromatography system.The solubility was expressed as a percentage of dissolved mass.By using a rheometer to measure viscosity,a thermogravimetric analyze to analyze thermal stability,and a scanning electron microscope to observe surface morphology of samples,the physical and chemical properties of KGSM could be obtained.UV-VIS,FT-IR and x-ray diffraction were utilized in analyzing the structure of KGSM,that the effect of 60Co ?-ray irradia-tion and hydrogen peroxide on the structure of KGM were initially ascertained.Next,hepatoma cell lines HepG2 acted as receptor cells to investigate the hypoglycemic and hypocholestrolemic activities of KGSM in vitro.The main results indicated as fol-lows:1.The Mw and PDI of samples with synergetic degradated by y-ray irradiation and hydrogen peroxide decreased to 6.48×104 Da and 1.19 respectively.The PDI of syn-ergetic degradated sample approached 1.0,which suggested an almost consistent composition of products.The solubility of synergetic degradated samples increased to 97.17%,and the thermal stability enhanced while the viscosity reduced.Following y-ray irradiation,the particles structure of KGM disappeared and the surface became porous.2.Structural characterization suggested that the backbone of KGM did not changed because there was no new chemical group being introduced into the structure.And infrared spectra showed the existence of ?-glycoside bond and mannose.X-ray dif-fraction pattern indicated that KGSM was an amorphous substance with partial ordered microcrystalline structures.3.The assay of glucose consumption and MTT indicated that KGSM inhibited the proliferation of HepG2 cells in the concentration of 0.1 mg/mL and 1 mg/mL.After eliminating the effect of cell proliferation on glucose consumption,the result showed that KGSM promoted glucose consumption of HepG2 cells most significantly in the concentration of 0.1 mg/mL(P<0.01).4.Insulin resistant HepG2 cells model was up by 10-8 mol/L insulin acting on HepG2 cells for 48 h,and the model was stable within 48 h.There was no significant difference in morphology between model cells and normal cells.KGSM could pro-mote glucose consumption of insulin resistant HepG2 cells in the concentration of 0.01 mg/mL and 1 mg/mL during 48 hours.The glucose consumption increased with time.And it came to the most obvious effectset when treated by KGSM in the concentra-tion of 0.1 mg/mL for 48 h(P<0.01).5.The regression equation of the standard curbe of cholesterol was:y=319.3744x—3.0881,r=0.9999(wherein y stand for peak area,x for cholesterol).In this case,there was a good linear relationship between the peak area and cholesterol content when the cholesterol content was between 0.28 ?g and 1.40 ?g.6.The optimum treated time for establishing high cholesterol HepG2 cells model was 24 h.The most significant effect in promoting cholesterol consumption appeared when the content of KGSM was 1 mg/mL(P<0.01). |
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