The Primary Structure Of Garlic Fructan

Garlic can be used as food and medicine. Bioactivities of garlic fructan (GF), which is the main functional component in garlic, have been reported such as immunity regulatory function. GF has great applied potential in the field of food, medicine and cosmetic. GF's bioactivity closely relates to its molecular structure. However, the GF's structure is still unclear. This thesis studied that by methylation, hydrolysis, gas spectrometry and mass spectrometry (GC/MS). The main results obtained follows.(1) Pure GF were obtained by water extraction, cation exchange resin separation,30%,40%, 50%,60%,70%,80%,90% ethanol precipitation, DEAE-52 and Sephadex G-100 column chromatography and was identified as pure by Sephadex G-100 column chromatography.(2) GF were hydrolyzed with the different sulfuric acid concentration, temperature and time. Degree of hydrolysis(DH) were determined by the 3,5-dinitrosalicylic acid (DNS) colorimetric method. The results showed that the affecting sequence for hydrolysis were temperature, time, sulfuric acid concentration consecutively. The best conditions for hydrolysis were 0.020 mol/L sulfuric acid,70℃and 2 hours and the highest DH was 76.19%.(3) The methylated garlic fructan (MGF) were hydrolyzed with the concentration of different sulfuric acid and trifluoroacetic acid (TFA), temperature and time. DH were determined by DNS colorimetric method. The results showed that the affecting sequence for hydrolysis were sulfuric acid concentration, temperature, time consecutively. The best conditions for hydrolysis were 0.40 mol/L sulfuric acid,100℃and 6 hours and the highest DH was 34.28%. Affecting sequence for TFA hydrolysis were same as sulfuric acid. The best conditions for hydrolysis were 0.50 mol/L sulfuric acid,100℃and 6 hours and the highest DH was 65.87%; DH of MGF with TFA was greater than sulfuric acid and MGF is fully dissolved in TFA. So TFA was more suitable for MGF hydrolysis. (4) In order to analyze the reaction mechanism of becoming osazone and hydrazone, they were prepared by phenyl hydrazine,2,4-dinitrophenyl hydrazine and reactived with 5% glucose or fructose solution. The reaction products is detected with Mass Spectrometry and Thin layer chromatography (TLC) method. The results showed that the reaction times for osazone of glucose and fructose were 5.3 minutes and 2.4 minutes respectively, occured in state C1 and C2 of monosaccharide, which were disubstituted reaction and the products were more than two; The times of becoming 2,4-dinitrophenylhydrazones of glucose and fructose were 24 hours or longer and occured in state C1 or C2 of monosaccharide respectively, which were Mono-substituted reaction and the product was only one. The difference might be due to steric effect and electronic effect of carbonyl reagent.The reaction was proned to side effects, which acetic acid and phenylhydrazine,2,4-dinitrophenylhydrazine reacted, the derivatives were acetyl phenylhydrazine and 2,4 dinitrophenol hydracetin respectively.(5) MGF was hydrolyzed, reduced and acetylized and produced derivatives which were analyzed with GC/MS. The result showed the degree of branch of GF was 17%.