| Hovenia dulcis,known as Zhi Ju or Guai Zao,belongs to Rhamnaceae.The peduncles of H.dulcis contain lots of nutrients,and are regarded as fruit and medicine.It is said that peduncles have unique effect of diuresis and detoxifying alcoholic intoxication.The present studies showed that the polysaccharides from peduncles of H.dulcis have antioxidant,anti-tumor,hepatoprotective effect against acute alcohol-induced liver injury and immune stimulation activity.In this thesis,separation and purification,physicochemical properties,preliminary structural characterization and bioactivities of polysaccharides from H.dulcis were studied by modern instrument analytical technologies.The main results are as follows:?1?Acquisition of polysaccharide fractions from H.dulcis.Three kinds of polysaccharide fractions,namely HDP1-1?HDP1-2 and HDP1-3 were obtained from H.dulcis by water extraction and ethanol precipitation?final ethanol concentrations were 40%,60% and 80%,respectively?.The homogeneous fraction SHDPs was isolated from spent Hovenia dulcis peduncles by alkali extraction.The yields were 4.2%,8.6%,6.1% and 1.5%,respectively.?2?The physicochemical properties determinations and preliminary structure characterization of polysaccharide of H.dulcis.The contents of total sugar of HDP1-1,HDP1-2,HDP1-3 and SHDPs were?97.26 ± 0.17?%,?92.90 ± 1.02?%,?95.48 ± 2.45?% and?80 ± 2.8?%,respectively.Protein contents of HDP1-2 and SHDPs were?3.23 ± 0.08?% and?2.3 ± 0.1?%,while HDP1-1 and HDP1-3 had no protein.The polysaccharide SHDPs contains uronic acid of?2.3 ± 0.09?%.The results of HPLC,UV,FT-IR and monosaccharide composition determination indicated that HDP1-1 and SHDPs are homogeneous polysaccharides with the molecular weight of 2187 kDa and 4570 kDa,respectively.HDP1-1 contains only galactose,while HDP1-2 and HDP1-3 are composed of glucose,rhamnose and a small amount of galactose,and HDP1-3 also contains a small amount of xylose.The fraction SHDPs is composed of seven monosaccharides of Rha,Fuc,Ara,Xyl,Man,Glc and Gal.Analysis of FT-IR,partial acid hydrolysis,methylation,GC-MS and NMR of the homogeneous polysaccharide fractions revealed that,HDP1-1 is mainly composed of?1 ?6?-?-D-Galp,and SHDPs is mainly composed of?1?3?-?-L-Rhap,?1?4?-?-D-Xylp,?1?6?-?-D-Glcp,?1?3?-?-D-Fucp,?1?3,6?-?-D-Galp and?1?3,6?-?-D-Manp.1-?-L-Araf and 1-?-D-Xylp are located on the side chains.?3?Preparation of a novel polysaccharide-zinc complex.A novel complex was prepared successfully by SHDPs and ZnCl2.On the basis of single-factor tests,the chelating time,initial concentration of Zn2+ and mass ratio of SHDPs to ZnCl2 were optimized by the orthogonal test.The optimum conditions were chelating time with 24 h,initial concentration of Zn2+ with 1 mg/mL and the mass ratio of SHDPs to ZnCl2 with 3 : 1.Under these conditions,the maximal chelating rate was 48.4%.An interaction of Zn2+ and SHDPs was carried out from Fourier transform infrared spectroscopy.The main type of interaction is hydroxyl,methylene and aromatic ring on the surface of SHDPs interacted with electric charge of Zn2+ and physical absorption.?4?Analysis of biological activities of polysaccharide-zinc complex and polysaccharide fractions from H.dulcis.Alcohol dehydrogenase assays in vitro showed that SHDPs has the ability to enhance ADH activity.Antioxidant activities assays in vitro indicated excellent DPPH and ABTS radical scavenging activities,medium superoxide radical scavenging activity and chelating ferrous ions ability.The immunoregulatory activities assays in vitro showed that HDP1-1,HDP1-2,HDP1-3 and SHDPs had no toxicity on macrophage RAW264.7.To a certain extent,they could increase the RAW264.7 cells proliferation,stimulate the NO production of macrophages and enhance the phagocytic function of the neutral red.HDP1-1,HDP1-2 and HDP1-3 could partly inhibit the proliferation of HepG2 cells by MTT method,and HDP1-3 showed the best inhibitory effects.The antitumor activities on HepG2 cells assays indicated that SHDPs-Zn2+ possessed stronger antitumor activities than SHDPs. |
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