甲壳低聚糖对α-葡萄糖苷酶活性的影响及降血糖作用

目的探讨甲壳低聚糖对α-葡萄糖苷酶活性的影响及降糖效果。方法在体外建立标准酶反应体系,分别加入6%甲壳低聚糖50,100,150,200,250,300μl,用4-硝基酚-α-D呋喃葡萄糖苷法测定酶活性;再建立加有6%阿卡波糖200μl的酶反应体系,测定酶活性;以250 mg/(kg.d)剂量灌胃,观察其对实验性糖尿病大鼠空腹及餐后血糖的影响。结果甲壳低聚糖对α-葡萄糖苷酶具有明显抑制作用,抑制效果接近于阿卡波糖;甲壳低聚糖能显著降低糖尿病大鼠空腹及餐后血糖。结论甲壳低聚糖可能具有阿卡波糖样的降血糖作用。     

甲壳低聚糖的调血脂作用

目的探讨甲壳低聚糖对高脂模型小鼠的降脂功效及其机理。方法采用高脂饲料连续饲养30 d建立小鼠高脂模型;同时,将壳聚糖酶解获得的甲壳低聚糖,以低、中、高(0.1、0.2、0.4 g·kg~(-1))3个不同的剂量分别给药。30 d后,眼眶取血,测血清中总胆固醇(TC)、甘油三酯(TG)、高密度脂蛋白胆固醇(HDL-C)和低密度脂蛋白胆固醇(LDL-C)含量。结果甲壳低聚糖能显著降低高血脂小鼠血清中的TC、TG和LDL-C含量,并能升高HDL-C的含量。结论甲壳低聚糖调血脂生物活性较为显著,具有很好的开发前景。     

甲壳低聚糖对糖尿病小鼠血糖和肠道菌群的影响

目的观察甲壳低聚糖对链脲佐菌素 (STZ)糖尿病小鼠血糖和肠道菌群的影响。方法将用STZ诱导的糖尿病模型小鼠分为糖尿病治疗组和糖尿病对照组 ,分别灌胃甲壳低聚糖 60 0mg (kg·d)和等体积的蒸馏水 ,连续 2 1d ,而后检测两组小鼠血糖及肠道菌群的变化。结果糖尿病治疗组小鼠的血糖降低、肠道菌群中双歧杆菌数量增多 ,与糖尿病对照组比较差异有显著性 (P <0 .0 5 )。结论甲壳低聚糖具有降低STZ糖尿病小鼠血糖及调节肠道菌群功能     

甲壳低聚糖硒对2型糖尿病大鼠胰岛素指标及胰腺组织的影响

目的观察甲壳低聚糖硒(COS-Se)对2型糖尿病大鼠的胰岛素含量、胰岛素敏感性及胰腺组织的影响。方法制备2型糖尿病大鼠模型,分别给予COS-Se、Se、甲壳低聚糖(COS)对其进行干预,观察20周,期间检测血糖、胰岛素的含量、胰岛素敏感指数及胰腺组织HE染色观察。结果 COS-Se、Se、COS对糖尿病模型的高胰岛素血症都有一定改善作用,随着时间的延长,COS-Se的改善作用更明显。结论 COS-Se可保护胰岛细胞,改善2型糖尿病大鼠的胰岛素敏感性。     

甲壳低聚糖对2型糖尿病造模大鼠胰岛β细胞的保护作用

目的观察甲壳低聚糖(COS)对2型糖尿大鼠胰岛β细胞的保护作用。方法试验大鼠经腹腔注射STZ 2周后,挑选葡萄糖耐量异常者继续给予高糖高脂饲料喂养,同时试验组用COS灌胃给药。分别在第0、4、8、12周剪尾取血测定空腹血糖及胰岛素水平,第16周末,股动脉取血,分离胰腺并固定做HE染色和胰岛原位细胞凋亡检测。结果 COS组空腹血糖、胰岛素水平和胰岛β细胞凋亡比例明显低于模型组。结论甲壳低聚糖具有改善胰岛素抵抗,保护胰岛β细胞的作用。     

甲壳低聚糖的制备和分析

解决壳聚精的水不溶性,拓宽壳聚精的应用范围。方法：直接用过氧化氢对高分子量、高脱乙酸化度的壳聚糖进行非均相降解、制备了水溶性甲壳低聚糖产品,对产品进行红外光谱结构表征,并用高效毛细管电泳测定了寡糖的聚合度。探讨了温度、过氧化氢浓度对降解所需时间、产品得率及甲壳低聚糖聚合度的影响。结果：选择降解温度 ８０℃～９０℃,过氧化氢浓度 ８％～１０％时,水解时间０．５ ～１．０ ｈ,水溶性产品得率为 ４０％～４５％,聚合度为３～７的寡糖占水解产物的３６％～５０％。结论：该方法制备甲壳低聚糖是可行的。如进一步研究工艺条件,有望进行工业化生产。     

不同分子量壳低聚糖抗菌作用的研究

目的　研究不同分子量的壳低聚糖抗金黄色葡萄球菌、大肠杆菌的能力及其最低杀菌浓度。方法　分别测定及比较加有壳低聚糖的培养基及空白培养基的菌浓。结果　不同分子量、不同浓度的壳低聚糖的抗菌作用强弱不一,同一规格壳低聚糖对金黄色葡萄球菌、大肠杆菌的作用强度不同。结论　壳低聚糖对金黄色葡萄球菌的抗菌作用随分子量的减小而增加,随浓度的增加而增加,对大肠杆菌作用很不明显,且无规律可寻。     

药用植物的活性成分：鞣花鞣质

随着对鞣质特别是鞣花鞣质(Ellagitannins)的分离、结构测定和各种生理活性的深入了解,使得实际具有生理活性的鞣质其原有的概念已发生了明显变化。本文根据鞣质结构的差别讨论其生理活性,如几种低聚鞣花鞣质的抗肿瘤作用和抗人类免疫缺陷病毒(Anti-HIV)作用。鞣花鞣质比相似结构的其他类型的鞣质具有更强的抗脂质过氧化作用。其他的生理活性还有:抑制致癌物的诱变和抑制肿瘤发展。     

甲壳胶囊对动物高脂血症的预防和治疗作用

观察了甲壳胶囊对小鼠、大鼠及家兔食饵性高脂血症的预防和治疗作用,结果表明：甲壳胶囊能降低动物血清TC、TG、LDL-C水平及TC／HDL-C比值,能升高动物血清HDL-C水平,还可降低血液粘度。     

低分子甲壳铵的理化性质及其抗肿瘤活性研究

目的研究低分子甲壳铵的理化性质 ,考察其抑制肿瘤的作用。方法采用电位滴定、凝胶色谱、紫外、红外等方法测定低分子甲壳铵的理化性质 ;用移植肿瘤试验 (S180 实体瘤 )方法 ,观察其抑制肿瘤作用。结果低分子甲壳铵相对分子质量均匀 ,水溶性好 ,给小鼠连续喂服 10d后与对照组比较 ,有明显的抑制肿瘤的作用 (P <0 .0 1)。结论低分子甲壳铵易溶于水 ,且具有一定的抑制肿瘤的作用。     

壳寡糖抗小鼠脑缺血/再灌注作用研究

目的探讨壳寡糖(chitooligosaccharides,COS)对小鼠局灶性脑缺血/再灌注损伤的影响及其机制。方法将♂ICR小鼠随机分为6组:假手术组、模型组、依达拉奉(3mg·kg-1)组及壳寡糖高、中、低剂量(200、100、50mg·kg-1)组。采用线栓法建立局灶性脑缺血/再灌注模型。观察壳寡糖对神经行为和脑梗死面积的影响。测定小鼠脑组织中丙二醛(MDA)和羰基含量,超氧化物歧化酶(SOD)、过氧化氢酶(CAT)及谷胱甘肽过氧化物酶(GSH-Px)活性。结果壳寡糖可明显改善小鼠神经功能缺陷,减少脑梗死面积,降低脑组织MDA和羰基含量,提高抗氧化物酶活性。结论壳寡糖具有抗脑缺血/再灌注损伤作用,可能与其抗氧化活性有关。     

Protective effects of ion-imprinted chitooligosaccharides as uranium-specific chelating agents against the cytotoxicity of depleted uranium in human kidney cells

Occupational internal contamination with depleted uranium (DU) compounds can induce radiological and chemical toxicity, and an effective and specific uranium-chelating agent for clinical use is urgently needed. The purpose of this study was to investigate whether a series of synthesized water-soluble metal-ion-imprinted chitooligosaccharides can be used as uranium-specific chelating agents, because the chitooligosaccharides have excellent heavy metal ion chelation property and the ion-imprinting technology can improve the selective recognition of template ions. DU-poisoned human renal proximal tubule epithelium cells (human kidney 2 cells, HK-2) were used to assess the detoxification of these chitooligosaccharides. The DU-chelating capacity and selectivity of the chitooligosaccharides were determined by inductively coupled plasma-mass spectrometry (ICP-MS). Cell viability, cellular accumulation of DU, membrane damage, DNA damage, and morphological changes in the cellular ultrastructure were examined to assess the detoxification of these chitooligosaccharides. The results showed that the Cu2?-imprinted chitooligosaccharides, especially the Cu2?-imprinted glutaraldehyde-crosslinked carboxymethyl chitooligosaccharide (Cu-Glu-CMC), chelated DU effectively and specifically, and significantly reduced the loss of cell viability induced by DU and reduced cellular accumulation of DU in a dose-dependent manner, owing to their chelation of DU outside cells and their prevention of DU internalization. The ultrastructure observation clearly showed that Cu-Glu-CMC-chelated-DU precipitates, mostly outside cells, were grouped in significantly larger clusters, and they barely entered the cells by endocytosis or in any other way. Treatment with Cu-Glu-CMC also increased the activity of antioxidant enzymes, and reduced membrane damage and DNA damage induced by DU oxidant injury. Cu-Glu-CMC was more effective than the positive control drug, diethylenetriaminepentaacetic acid (DTPA), in protection of HK-2 cells against DU cytotoxicity, as a result of its chelation of UO?2? to prevent the DU internalization and its antioxidant activity.     

Antioxidant activities of chitobiose and chitotriose

Chitooligosaccharides, the oligomers made up of beta-1,4-linked D-glucosamine, are obtained by partial hydrolysis of chitosan, a deacetylation product of chitin. The antioxidant activity of various chitooligosaccharides was tested in vitro with aminoguanidine, pyridoxamine, and Trolox as reference compounds. Hydroxylation of benzoate to salicylate by H2O2 in the presence of Cu(2+) was effectively inhibited by chitobiose, chitotriose, aminoguanidine, pyridoxamine, and Trolox (their IC(50) values=18, 80, 85, 10, and 95 microM, respectively), whereas glucosamine and N-acetylchito-oligosaccharides (di-N-acetylchitobiose and tri-N-acetylchitotriose) did not show any inhibitory activity. Chitobiose and chitotriose were more potent than the 3 reference compounds in scavenging hydroxyl radicals produced by photolysis of zinc oxide: IC(50) values of the 2 oligomers were 30 and 55 microM, respectively. Such a scavenging activity of these 2 chitooligomers was also shown by the use of another system, a mixture of Fe(3+)/EDTA/ascorbate/H2O2, for producing hydroxyl radicals. Only chitobiose and Trolox, of the 10 compounds tested, had the ability to scavenge superoxide radicals generated by a non-enzymatic system using phenazine methosulfate and NADH. Taken together with our unpublished observation that chitobiose and chitotriose are appreciably absorbed from the intestine of rats, the present results suggest that these 2 chitooligosaccharides would act as effective antioxidants in vivo when orally ingested.     

Effect of chitobiose and chitotriose on carbon tetrachloride-induced acute hepatotoxicity in rats

The purpose of the present study was to examine whether chitobiose and chitotriose can protect rats from CCl4-induced hepatic toxicity when given orally. We studied the effects of the 2 chitooligosaccharides given orally to rats on the acute hepatotoxicity induced by CCl4-dependent lipid peroxidation. The increase in the sum of malondialdehyde and 4-hydroxy-2-alkenals, a marker of lipid peroxidation, in both plasma and liver of CCl4-treated rats was suppressed by oral administration of chitobiose or chitotriose. The elevation in the levels of plasma aspartate transaminase and alanine transaminase activities, markers of hepatic injury, induced by CCl4 intoxication was also counteracted by oral administration of either chitooligosaccharide. The results indicate that chitobiose and chitotriose have the ability to exert a protective action against CCl4-induced acute hepatoxicity, probably by their antioxidant activity.     

壳寡糖降血糖作用的实验研究

目的：探讨壳寡糖的降血糖作用.方法：以尾静脉注射四氧嘧啶建立糖尿病大鼠模型,随机分为模型对照组,壳寡糖高、中、低剂量组,二甲双胍组和正常对照组,每组6只.观察壳寡糖对糖尿病大鼠血糖、胰岛素的影响及病理改变,观察壳寡糖对正常小鼠血糖及糖耐量的影响.结果：壳寡糖中、高剂量组均有明显降低四氧嘧啶糖尿病大鼠血糖作用（P＜0.05）.壳寡糖改善模型对照组大鼠胰腺功能,3个剂量组壳寡糖使血中胰岛素有升高趋势,但与模型对照组比较差异无统计学意义.壳寡糖低、中、高剂量组与空白对照组小鼠血糖比较差异无统计学意义（P＞0.05）,中、高剂量壳寡糖使小鼠灌胃葡萄糖后0.5 h血糖降低,与空白对照组比较差异有统计学意义（P＜0.05）.结论：壳寡糖具有明显降血糖作用,对正常小鼠血糖无影响,增加小鼠糖耐量作用.     

In vitro antimicrobial activity of a chitooligosaccharide mixture against Actinobacillus actinomycetemcomitans and Streptococcus mutans.

The purpose of this study was to evaluate the in vitro antibacterial activity of a chitooligosaccharide mixture (MW 2000–30 000 Da) with a deacetylation degree of 91.5% against two representative oral pathogens, Actinobacillus actinomycetemcomitans and Streptococcus mutans. A 0.1% concentration of the chitooligosaccharides (derived from the exoskeletons of marine crustaceans) was used to estimate antibacterial activity. Approximately 2 log colony forming units (CFU)/ml of A. actinomycetemcomitans were inactivated by 0.1% chitosan after 30 min, while 120 min exposure inactivated about 4.5 log CFU/ml of this organism. In contrast, the level of inactivation against S. mutans was less than 0.5 log CFU/ml after an exposure of up to 120 min. Electron microscopy showed that the exposure of A. actinomycetemcomitans to the chitooligosaccharides resulted in the disruption of cell membranes and that it could be considered for the treatment of periodontal diseases associated with A. actinomycetemcomitans.     

壳寡糖对小鼠微循环及移植性肿瘤的影响

目的探讨壳寡糖的作用机制。方法观察壳寡糖对小鼠耳廓小动脉的血流变化,对S180肉瘤的影响和对肝癌H22实体瘤的影响。结果壳寡糖能加快小鼠耳廓小动脉的血流速度,对S180肉瘤和肝癌H22实体瘤具有明显的抑制作用。结论壳寡糖对小鼠微循环和移植性肿瘤具有显著的影响。     

壳寡糖减弱内毒素对小鼠巨噬细胞的损伤作用

目的观察壳寡糖对内毒素刺激的小鼠巨噬细胞(RAW 264.7)的影响。方法采用半定量RT-PCR检测IL-1β的基因水平变化,ELISA分析蛋白水平变化,流式细胞仪分析细胞凋亡情况。结果壳寡糖可显著抑制内毒素介导的炎症细胞因子IL-1β的增高,0.4 mg/mL的壳寡糖抑制效果最为明显,并显著降低内毒素介导的细胞凋亡。结论壳寡糖可显著保护内毒素介导的细胞损伤。