壳聚糖衍生物抗菌活性研究进展

壳聚糖具有降低血液中胆固醇、降低血压、抗感染、控制关节炎、抗癌等多种作用。作为天然的食品防腐剂,壳聚糖不仅对人体无害,还具有很多保健作用。普通分子量的壳聚糖水溶性很差,一般使用酸溶液来溶解。通过合成各种壳聚糖的衍生物不仅提高了壳聚糖的水溶性还增强了它们的抗菌活性,使壳聚糖作为一种天然优质食品防腐剂成为可能。     

天然高分子甲壳素／壳聚糖及其衍生物在造纸中的应用

天然高分子甲壳素／壳聚糖具有与纤维素的结构相近的特点，与纤维素有极好的相容性，已成为造纸化学品的重要原料之一，本文简要介绍了甲壳素／壳聚糖的来源、性质、结构，并对其在造纸工业的应用，尤其作为施胶剂、纸张增强剂、助留剂等造纸助剂的研究进行概述。     

羧甲基硫脲壳聚糖的结构表征及抑菌活性研究

运用红外光谱、紫外光谱和差热-热重分析对合成的羧甲基硫脲壳聚糖进行结构表征,并研究羧甲基硫脲壳聚糖对大肠杆菌、金黄色葡萄球菌的抑菌活性。结果表明：硫脲壳聚糖中羟基发生了羧甲基化反应,与壳聚糖相比热稳定性降低;羧甲基硫脲壳聚糖对大肠杆菌、金黄色葡萄球菌的抑菌活性较壳聚糖本身增强,对大肠杆菌、金黄色葡萄球菌最小抑菌质量浓度(MIC)均为0.20mg/mL。     

二元取代壳聚糖季铵盐的抗菌活性

对合成的系列单取代和双取代壳聚糖季铵盐进行了抗菌试验。实验结果表明，单取代壳聚糖季铵盐抗菌活性弱于双取代壳聚糖季铵。在双取代壳聚糖季铵盐中，O-季铵化-N-壳聚糖内桂醛席夫碱的最低抑菌浓度（MIC）最小，对金黄色葡萄球菌和大肠杆菌的MIC分别达到了为0．01％和0．02％。试验结果表明，壳聚糖衍生物抗菌活性与结构之间有一定的构效关系。     

壳聚糖对革兰氏阴性菌抑菌机理的初步研究

体外抑菌法研究壳聚糖对绿脓杆菌、奇异变形杆菌和大肠杆菌的抑菌性能。同时,对细菌表面的亲水性和负电荷进行研究,以阐述革兰氏阴性菌表面性质与壳聚糖对其抑菌性能之间的关系。以大肠杆菌作为代表性菌株,考察了壳聚糖对革兰氏阴性菌的抑菌机理。通过测定菌液中加入疏水性荧光探剂1-N-苯萘胺(NPN)后荧光强度的改变,考察壳聚糖对外膜渗透性的影响。此外,采用红外吸收光谱(FT-IR),对壳聚糖和大肠杆菌的作用产物进行表征。结果表明：革兰氏阴性菌表面的亲水性越好,所带的负电荷越多,壳聚糖表现出较好的抑菌性能;壳聚糖可增加细胞外膜的渗透性,壳聚糖与细胞膜间发生静电作用而使细胞膜破坏,最终导致菌体的死亡。     

O-羧甲基化壳聚糖季铵盐的制备及抑菌活性

目的：制备抑菌活性较壳聚糖强的水溶性壳聚糖衍生物。方法：以3-氯-2-羟丙基三甲基氯化铵(CTA)和氯乙酸为接枝改性剂,制备水溶性O-羧甲基化壳聚糖季铵盐,采用红外光谱和紫外光谱对其结构进行表征,并研究O-羧甲基化壳聚糖季铵盐对大肠杆菌(E.coli)、金黄色葡萄球菌(S.aureus)和黑曲霉(A.niger)的抑制作用。结果：水溶性的O-羧甲基化壳聚糖季铵盐对E.coli、S.aureus和A.niger均有显著的抑菌活性。结论：与壳聚糖相比,水溶性的O-羧甲基化壳聚糖季铵盐的抑菌活性提高。     

Chitin/Chitosan — Safe, Ecofriendly Packaging Materials with Multiple Potential Uses

Increased and indiscriminate use of plastic packaging films, which are petroleum based, has led to ecological problems due to their total non-biodegradability. Continuous use of plastics in any form or shape has to be restricted and may even be gradually abandoned to protect and conserve ecology. Such awareness, of late by one and all, has led to a paradigm shift to look for packaging films and processes that are biodegradable and therefore, compatible with the environment. Such an approach also leads to natural resource conservation with an underpinning on a pollution-free environment. Thus, the concept of biodegradability enjoys both user-friendly and eco-friendly attributes, and the raw materials are essentially derived from either replenishable agricultural feed stocks (cellulose, starch, and proteins) or marine food processing industry wastes (chitin/chitosan). Their total biodegradation to environmentally friendly benign products (CO₂, H₂O/quality compost) is the turning point that needs to be capitalized upon. Polymer cross-linking and graft copolymerization of natural polymers with synthetic monomers are other alternative approaches of value to using biodegradable packaging films. Although complete replacement for synthetic plastics may be impossible to achieve and perhaps even unnecessary, at least for a few specific applications, our attention and efforts are required in the days to come. Though expensive, biopackaging meets tomorrow's need for packaging, especially for a few value added products. It offers an attractive route to waste management, as well. Nonetheless, everyone desires a clean, pollution-free environment in the future.     

甲壳素及壳聚糖在医药领域的应用研究进展

对甲壳素及壳聚糖在医药领域的应用研究进展作一综述。     

Antibacterial Activity of Ozone‐Depolymerized Crawfish Chitosan

ABSTRACT: Antimicrobial activities of chitosan samples with different molecular weights (1333, 432, 201, 131, and 104 kDa) prepared by ozone treatment were examined against 2 Gram‐positive bacteria (Listeria monocytogenes and Staphylococcus aureus) and 2 Gram‐negative bacteria (Escherichia coli and Pseudomonas fluorescen) to investigate the effect of chitosan's molecular weight and concentration on the inhibition of bacterial growth. Antimicrobial activity of chitosan varied depending on the molecular weight, concentration of chitosan, and type of microorganism. Generally, the effectiveness of the chitosans significantly increased with increasing chitosan concentration, regardless of molecular size and types of bacteria. Chitosan with molecular weights ranging from 104 to 201 kDa showed relatively greater antimicrobial activity against L. monocytogenes, S. aureus, and P. fluorescen; whereas for E. coli, intermediate molecular weight chitosan was more effective in growth inhibition than lower or higher molecular weight chitosan particularly at 0.1% concentration.     

Effect of Chitosan Physical Form on Its Antibacterial Activity Against Pathogenic Bacteria

The antibacterial activity of chitosan (CS) nanospheres, in comparison with other physical forms, was investigated against Salmonella enterica serovar Typhimurium and Staphylococcus aureus, which are 2 foodborne harmful pathogens. Results showed that the antibacterial efficacy of CS nanospheres: (1) was superior to that displayed by CS in powder and solution form; (2) was higher against S. aureus than against Salmonella Typhimurium; and (3) was dependent on the temperature and pH of the medium depending on the strain. For S. Typhimurium, a higher activity was displayed at 37 °C, in which 99.9% of the population was eradicated independently of the pH, followed by 20 °C and 7 °C, in which acidic pH conditions favored a higher susceptibility of bacteria to the effect of CS. On the contrary, S. aureus was less susceptible to the pH and temperature conditions of the medium, and no statistical difference in the antibacterial effect was observed for pH 5.8 and 8.0 at 20 °C and 37 °C. However, at 7 °C a slightly higher activity was displayed at pH 5.8 than at 8.0.     

非生物性因素对壳聚糖抗菌活性的影响

以具有代表性的两类病原菌:金黄色葡萄球菌和大肠杆菌为实验菌种,研究了不同的酸溶液、金属离子、离子强度和pH等非生物性因素对壳聚糖抗菌活性的影响。结果表明:在壳聚糖的酸溶液中,低碳数的有机酸比高碳数的有机酸和常见的无机酸更有利于壳聚糖抗菌活性的发挥;在pH6.0的环境中,壳聚糖的抗菌活性最强;由于与壳聚糖的螯合作用,Zn2+的加入对于壳聚糖的抗菌效率影响最大,Mg2+的影响相对最小;离子强度的增大可以更好地提高壳聚糖的抗菌活性。     

甲壳素的酶水解机理及动力学研究进展

甲壳素和壳聚糖不仅可被甲壳素酶、壳聚糖酶和溶菌酶水解 ,还可以被一些包括蛋白酶、脂肪酶和其它糖酶的非专一性酶水解 ,这些酶对甲壳素和壳聚糖解聚的作用机理和动力学 ,对于开发甲壳素和壳聚糖在食品、化工、医药、农业等领域中的应用具有重要意义 .为此 ,介绍了近年来国外的研究进展 .     

壳聚糖对金黄色葡萄球菌抑菌活性的研究

研究了壳聚糖对金黄色葡萄球菌抑菌活性,考察了不同壳聚糖浓度、pH值、金属离子、醋酸浓度对壳聚糖抑制金黄色葡萄球菌活性的影响,并以壳聚糖浓度、pH值、醋酸浓度为因素进行正交试验,确定了壳聚糖对金黄色葡萄球菌抑菌活性的最优条件。实验结果表明,壳聚糖对金黄色葡萄球菌的抑制能力随其浓度的升高而增强;壳聚糖溶于浓度为2%的醋酸溶液时,培养基pH控制在6.0时壳聚糖的抑菌活性最强;金属离子在一定程度上降低了壳聚糖的抑菌活性;这3个因素对壳聚糖的抑菌活性的影响程度为壳聚糖浓度pH值醋酸浓度。     

抗菌性玉米醇溶蛋白/壳聚糖复合膜的制备与性质

采用分步法,先配制壳聚糖/醋酸/乙醇溶液体系,再向其中加入玉米醇溶蛋白,最后利用流延法制成玉米醇溶蛋白/壳聚糖(zein/chitosan,Z/C)复合膜,探讨壳聚糖质量分数对Z/C复合膜理化性质与抗菌特性的影响。结果表明:在壳聚糖质量分数为2%~8%范围内,混合溶液的黏度和电导率随壳聚糖质量分数变化成阶梯状变化,且壳聚糖的添加对复合膜性质有显著影响,Z/C复合膜的断后伸长率从1.00%提高到6.67%,接触角从65.97°减小到53.61°,水蒸气透过率从5.23 g·m/(m2·h·Pa)提高到9.16 g·m/(m2·h·Pa);扫描电子显微镜观察,复合后薄膜保持光滑、均一;大肠杆菌抑菌实验表明添加壳聚糖使复合膜具有较强的抗菌特性。     

甲壳素、壳聚糖的保健功能及应用展望

甲壳素是存在于自然界中惟一能被生物降解的带正电荷高分子材料,近年研究表明,它在调节机体免疫功能,降血脂、血糖、血压,保护胃肠道等方面发挥着巨大的作用.壳聚糖是甲壳素的N-脱乙酰基衍生物,具有组织相容性好、生物学活性多样、可生物降解、无毒、易于吸收等特点.本文介绍了甲壳素、壳聚糖的保健功能特性,以及甲壳素和壳聚糖在食品工业中的应用,对于甲壳素的应用前景以及新产品的开发具有一定的指导意义.     

负载小麦醇溶蛋白纳米银胶体颗粒的抗菌壳聚糖复合膜构建及表征

本研究采用浇筑法,成功构建了Ag NPs/小麦醇溶蛋白/壳聚糖复合抑菌膜,实现了Ag NPs的稳态化和协同增效。自组装的小麦醇溶蛋白(gliadin),同时充当AgNPs的螯合剂和稳定剂,有效抑制了纳米银颗粒(AgNPs)团聚。与其他复合膜相比,gliadin/Ag NPs复合膜透明度良好。SEM和EDS证实Ag NPs均匀分布于复合膜。此外,gliadin/AgNPs复合颗粒具有优异的缓释特性。人皮肤成纤维细胞评估结果表明复合膜具有更好的生物相容性,激光共聚焦显微镜(CLSM)显示gliadin/Ag NPs复合膜对大肠杆菌与金黄色葡萄球菌具有更强的抗菌效果。这些薄膜在抗菌食品包装材料、伤口敷料以及植入物的开发方面极具应用价值。     

月桂酸衍生物的合成与抑菌性的比较研究

本文进行了月桂酸衍生物(月桂酸单甘酯GML、月桂酸双甘酯和三甘酯GDL+GTL、聚甘油月桂酸单甘酯PGML)合成的研究,并比较了其抑菌活性和皮肤致敏性,以获得应用性能更佳的月桂酸产品。采用固体酸性盐催化的酯化反应合成月桂酸衍生物,优化的反应条件为:催化剂NaHSO4用量为月桂酸重的0.3%,底物摩尔比为1:2,温度200℃、真空条件下反应5h;反应产物采用分子蒸馏提纯,得到的月桂酸单甘酯和聚甘油月桂酸单甘酯纯度较高。采用平板菌落计数法测定月桂酸衍生物的最低抑菌浓度,结果表明:月桂酸、GML和PGML对革兰氏阳性菌和阴性菌均有较好的抑菌活性,但在相同条件下月桂酸和GML的抑菌效果要优于PGML,GDL+GTL则无抑菌活性。通过皮肤致敏性测试,证实月桂酸衍生物均不会导致人体皮肤过敏。     

Antibacterial Activities of Chitosans and Chitosan Oligomers with Different Molecular Weights on Spoilage Bacteria Isolated from Tofu

Seven bacteria were isolated from spoiled tofu and identified as Bacillus sp. (S08), B. megaterium (S10), B. cereus (S17, S27, S28, S32), and Enterobacter sakazakii (S35). In a paper disc test with 6 chitosans and 6 chitosan oligomers of different molecular weights, chitosans showed higher antimicrobial activity than did chitosan oligomers at a 0.1% concentration. Results of inhibitory effects of 6 chitosans on growth of Bacillus sp. (S08) failed to detect viable cells after incubation for 24 hrs at 37 C, even at 0.02% concentration. With B. megaterium (S10) and B. cereus (S27), a 3 to 4 log cycle reduction was found in the chitosan‐treated group. The growth of Enterobacter sakazakii (S35) was completely suppressed in the presence of 0.04% chitosan except for 1 chitosan product. The minimum inhibitory concentration of chitosan differed with products and isolates, ranging from 0.005% to above 0.1%.     

芦根多糖的超声辅助提取及其抗菌活性

在单因素试验的基础上,采用Box-Behnken试验优化超声辅助提取芦根多糖的最佳工艺条件,然后研究芦根多糖抗菌活性。结果表明,超声辅助提取芦根多糖的最佳工艺条件为液料比9.9:1(mL/g)、超声温度60℃、超声时间52min,此时芦根多糖得率9.06%;超声辅助提取获得的芦根多糖对酵母菌属于极敏感,对金黄色葡萄球菌属于高敏感,对枯草芽孢杆菌和黑曲霉属于中敏感。     

壳聚糖／甲壳素及其衍生物的食品应用

甲壳素是从甲壳类动物等无脊椎动物外壳提取的多糖类天然高分子,是地球上含量仅次于纤维素的生物聚合物,称为聚β（1－4）－2－乙酰氨基－2－脱氧－D－葡萄糖。壳聚糖是低乙酰度的甲壳素,称为聚β（1－4）－2－氨基2－脱氧－D－葡萄糖。甲壳素／壳聚糖性质独特、资源丰富,其应用范围广泛。本介绍了甲壳素、壳聚糖及其衍生物的抗微生物活性及在食品方面的应用,包括食用膜、液体处理剂、食品添加剂和保鲜剂。