桑叶多糖提取分级及其抗辐射氧化胁迫作用

发布时间：2023-01-31 06:30

　　桑叶为桑科植物桑Morus alba L的干燥叶,药食同源。桑叶多糖具有降血压、血脂、抗炎等包括免疫刺激作用等多种生物活性,本研究以桑叶为研究对象,研究了桑叶多糖（MLP80%）的提取工艺、理化性质及抗辐射氧化胁迫作用。对超声波辅助和热水浸提2种提取工艺后桑叶残渣的形态特征和结构变化进行扫描电镜（SEM）分析,表明超声辅助提取对提高生物活性物质的传质速率有积极作用。结合单因素试验,采用响应面分析法优化桑叶多糖（MLP）的超声辅助提取工艺,确定了最佳提取条件:提取温度60℃,超声功率60 W,提取时间30 min,提取溶剂（水）与原料的比例（V/W,mL/g）为30:1;多糖提取率为6.86±0.15%。采用乙醇对桑叶多糖进行分级,得到4个多糖级分（MLP20%、MLP40%、MLP60%和MLP80%）。通过体外抗氧化活性试验筛选,MLP80%具有更好抗氧化活性。采用化学和物理分析方法,测定了MLP80%和MLP中多糖、蛋白质、糖醛酸、硫酸根和总多酚的含量、溶解度和溶胀度等理化特性,MLP80%多糖含量显著高于MLP（P≤0.05）,而MLP中蛋白质、糖醛酸和总多酚含量显著高于MLP8... 

【文章页数】：97 页

【学位级别】：硕士

【文章目录】：
摘要
Abstract
Chapter1 Introduction
    1.1 Source,Background and Significance of the Research
        1.1.1 Source of the Research project
        1.1.2 Research background
        1.1.3 Theoretical and practical Significance of the Research
    1.2 Background of mulberry polysaccharides
    1.3 Biological properties of mulberry leaf
        1.3.1 Antihyperglycaemic effect
        1.3.2 Antihyperlipidaemic effect
        1.3.3 Anti-obesity effect
        1.3.4 Anti-oxidative effect
        1.3.5 Anti-inflammatory effect
    1.4 Relationship between Polysaccharide structure and bioactivity
    1.5 Polysaccharide extraction methods
    1.6 In ovo treatment
        1.6.1 Advantages of in ovo model
        1.6.2 In ovo administration and the immune System
        1.6.3 Immune status indicators
    1.7 Oxidative stress and immunity
    1.8 Research contents
Chapter2 Materials and methods
    2.1 Chemical reagents and laboratory equipment
        2.1.1 Chemical reagents
        2.1.2 Laboratory equipment
    2.2 Extraction method
    2.3 Preparation of crude polysaccharide
    2.4 Optimization of the extraction conditions
        2.4.1 Single factor experiments
        2.4.2 Experimental design of Response surface model
    2.5 Isolation of polysaccharide fractions and their antioxidant activity in vitro
        2.5.1 Assay of DPPH radical scavenging activity
        2.5.2 Assay of ABTS radical scavenging activity
        2.5.3 Assay of Hydroxyl radical scavenging activity
        2.5.4 Assay of Superoxide radical scavenging activity
        2.5.5 Assay of reducing power
    2.6 Physicochemical properties of crude MLP and MLP80%
        2.6.1 Determination of chemical contents
        2.6.2 Determination of solubility and swelling power
        2.6.3 Determination of molecular weight
        2.6.4 UV analysis
        2.6.5 FT-IR spectrometric analysis
    2.7 Effects of MLP80%in ovo
        2.7.1 In ovo Injection and Egg Management
        2.7.2 Experimental design
        2.7.3 Body weight determination
        2.7.4 Determination of organ indexes
        2.7.5 Lipid peroxidation and antioxidant capacity in serum
        2.7.6 Determination of immune cytokines
    2.8 Statistics analysis
Chapter3 Extraction,isolation and physicochemical properties of polysaccharide from mulbery leaves
    3.1 Introduction
    3.2 Extraction of mulberry leaf polysaccharides
        3.2.1 Scanning electron microscopy(SEM)
        3.2.2 Single factor experiments
            3.2.2.1 Effect of extraction temperature on MLP yield
            3.2.2.2 Effect of solid to liquid ratio on MLP yield
            3.2.2.3 Effect of extraction time on MLP yield
            3.2.2.4 Effect of ultrasonic power on MLP yield
        3.2.3 Optimization of MLP extraction by response surface model(RSM)
            3.2.3.1 Model fitting and statistical analysis
            3.2.3.2 Analysis of response surface plots
            3.2.3.3 Verification of predictive model
    3.3 Isolation of polysaccharide fractions and their antioxidant activity in vitro
        3.3.1 DPPH radical scavenging activity
        3.3.2 ABTS radical scavenging activity
        3.3.3 Hydroxyl radical scavenging activity
        3.3.4 Superoxide radical scavenging activity
        3.3.5 Reducing power
    3.4 Physicochemical properties of crude MLP and MLP80%
        3.4.1 Determination of chemical contents
        3.4.2 Solubility and swelling power
        3.4.3 Determination of molecular weight
        3.4.4 UV analysis
        3.4.5 FT-IR spectrometric analysis
    3.5 Brief Summary
Chapter4 Effects of MLP80%against radiation induced oxidative stress
    4.1 Introduction
    4.2 In ovo pretest experiments
        4.2.1 MLP concentration
        4.2.2 Radiation dose
    4.3 Effects of MLP80%in ovo model
        4.3.1 Effect of MLP 80% on body weight
        4.3.2 Effect of MLP 80% on organ indexes
        4.3.3 Effect of MLP 80% on lipid peroxidation
        4.3.4 Effect of MLP 80% on antioxidant capacity
            4.3.4.1 Effect of MLP 80% on catalase(CAT)
            4.3.4.2 Effect of MLP 80% on glutathione peroxidase(GSH-Px)
            4.3.4.3 Effect of MLP 80% on superoxide(SOD)
        4.3.5 Effect of MLP 80% on cytokines in serum
            4.3.5.1 Effect of MLP 80% on interleukin-2(IL-2)
            4.3.5.2 Effect of MLP 80% on interleukin-12(IL-12)
            4.3.5.3 Effect of MLP 80% on interferon-γ (IFN-γ)
    4.4 Brief Summary
Conclusion
结论
References
Appendix
Papers and Other Achievements Published during Master's Degree Study
Acknowledgement
Resume



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