食品科学 ›› 2020, Vol. 41 ›› Issue (12): 67-76.doi: 10.7506/spkx1002-6630-20190603-015

• 食品化学 • 上一篇    下一篇

不同取代度水溶性羧甲基茯苓多糖的制备、结构表征及体外抑菌活性

别蒙,谢笔钧,孙智达   

  1. (华中农业大学食品科学技术学院,湖北 武汉 430070)
  • 出版日期:2020-06-25 发布日期:2020-06-22
  • 基金资助:
    湖北特色农产品深加工关键技术装备与产业化示范项目(2016-620-000-001-044)

Preparation, Structural Characterization and in Vitro Antibacterial Activity of Water-Soluble Carboxymethyl Pachymaran with Different Degrees of Substitution

BIE Meng, XIE Bijun, SUN Zhida   

  1. (College of Food Science and Technology, Huazhong Agricultural University, Wuhan 430070, China)
  • Online:2020-06-25 Published:2020-06-22

摘要: 为提高茯苓多糖的水溶性和提高其生物活性,以一氯乙酸为羧甲基化试剂合成羧甲基茯苓多糖(carboxymethylated pachymaran,CMP),并对不同取代度水溶性CMP进行结构表征及体外抑菌活性分析。结果表明:羧甲基化反应的最佳条件为反应温度65 ℃、反应时间4 h、反应溶剂乙醇体积分数80%、反应物茯苓多糖-氢氧化钠-一氯乙酸物质的量比为1∶3.5∶1.75,此条件下,CMP的平均取代度为0.724;通过调控反应条件可制备出不同取代度的CMP,取代度范围为0.350~0.728;红外光谱分析结果表明茯苓多糖衍生化成功;高效凝胶渗透色谱法测定取代度越高,分子质量越小;取代度越高的CMP Zeta电位绝对值越大,粒径先增大后减小,中性糖含量越低,热稳定性先增大后减小;核磁共振光谱分析结果表明羧甲基衍生化反应主要发生在C6位的羟基上;扫描电镜显示取代度越高,空间结构越紧密,裂解情况越严重。体外实验发现,CMP对食源性致病菌的抑制能力随取代度的增加而增强,对革兰氏阳性菌的抑制能力强于革兰氏阴性菌。

关键词: 茯苓多糖, 化学修饰, 结构表征, 抗菌活性

Abstract: To improve the water solubility and bioactivity of pachymaran, carboxymethylated pachymaran (CMP) was synthesized with monochloroacetic acid as carboxymethylation reagent. The structures of CMP with different degrees of substitution were characterized and their bacteriostatic activity were analyzed in vitro. The results showed that the optimum reaction conditions were as follows: temperature, 65 ℃; etherification time, 4 h; ethanol concentration, 80%; and molar ratio of pachymaran to sodium hydroxide to monochloroacetic acid, 1:3.5:1.75. Under these conditions, the average degree of substitution (DS) was 0.724. CMP with DS in the range of 0.350 to 0.728 could be prepared by controlling the reaction conditions. The results of Fourier transform-infrared (FT-IR) spectroscopy analysis showed that pachymaran was successfully derivatized. Gel permeation chromatography coupled online to multi-angle laser light scattering (GPC-MALLS) revealed that higher the DS, the smaller the molecular mass and the higher the absolute value of Zeta potential of CMP. In addition, the particle size increased first and then decreased, the content of neutral sugar decreased continuously, and the thermal stability firstly increased and then decreased. The results of nuclear magnetic resonance (NMR) showed that carboxymethyl derivatization mainly occurred at the hydroxyl position of C6. Scanning electron microscopy (SEM) showed that the higher the DS, the closer the spatial structure and the higher the degree of cracking. In vitro tests showed that the inhibition of CMP against foodborne pathogens was enhanced with increasing DS, and it was more active against Gram-positive bacteria than against Gram-negative bacteria.

Key words: pachymaran, chemical modification, structural characterization, antimicrobial activity

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