高相对分子质量甲壳素、壳聚糖的制备

采用红外光谱分析甲壳素、壳聚糖的主要性能指标，研究了EDTA和HCI用于制备甲壳素的脱钙工艺，其结果为：EDTA可替代HCI用于制备甲壳素的脱钙工艺，特别是由于其所特有的脱钙机理，脱钙时对甲壳素碳骨架基本无损伤，因此其产品的分子质量较HCI法的大，在同等条件下，可制得高相对分子质量的甲壳素和壳聚糖。其它性能指标如产率，脱乙酰度，颜色等均优于采用HCI法制得的产品。此外，EDTA法还可减少环境污染，而不增加成本。     

甲壳素及其衍生物壳聚糖的应用进展

甲壳素(Chitin)是自然界中含氨基的均态多糖之一,广泛存在于甲壳类动物中,是仅次于纤维素的天然高分子化合物.壳聚糖(Chitosan)是甲壳素脱乙酰基产生的主要衍生物.甲壳素结构中含有多种官能团,壳聚糖分子中存在许多游离胺基,因而具有许多独特的性质.同时,二者具有很好的生物相容性,可降解性等特点,因而在许多领域具有广泛的应用.     

工艺过程中温度对甲壳素分子的影响

甲壳素的制备多以虾、蟹的甲壳为原料通过稀酸脱盐和稀碱消化蛋白质的方法,本文以该法为基础,考察了制备过程中温度变化对甲壳素分子的影响。综合表明了常温制备甲壳素除吸附水外尚含有缔合水。表观粘度分析结果表明常温处理可较好地维持甲壳素分子的聚合度。     

甲壳素及其衍生物壳聚糖的药理作用和临床应用研究进展

甲壳素及其衍生物壳聚糖是一种用途很广的天然高分子化合物,具有无毒、生物相容性好、吸附功能强、生物可降解等优异性能。随着对新材料的研究开发,甲壳素和壳聚糖在医药和卫生材料方面的研究成果已得到实际应用,甚至已工业化生产。综述了甲壳素和壳聚糖抗菌、止血、促愈合、提高免疫的药理作用及其在医用敷料方面的应用。     

甲壳素及壳聚糖的医药应用

甲壳素是广泛存在于自然界的一种天然高分子材料，壳聚糖为其脱乙酰基衍生物。本文着重介绍甲壳素及壳聚糖在医药学上的应用。     

甲壳素及其衍生物作为缓释辅料的应用

甲壳素是一种天然多糖 ,广泛存在于节肢动物的壳和真菌的细胞壁中 ,其化学名称为 (1,4 )聚乙—乙酰氨基— 2—脱氧—β—Ｄ—葡萄糖。每年自然界生物合成量约达数十亿吨 ,是地球上存在量仅次于纤维素的一种天然多糖。甲壳素的主要衍生物是甲壳胺 ,其用途很广。在医药上 ,甲壳胺可作为酶、抗原、抗体的固定化载体 ;甲壳素可用于人造皮肤血管、手术缝合线。甲壳素及其衍生物还是伤口愈合的促进剂。另外 ,甲壳素衍生物甲壳硫酸酯 ,具有类似肝素的功能 ,如抗炎、抗凝、降血脂、降低血管通透性等。由于甲壳素及其衍生物的独特性质 ,近年来随着新…     

甲壳素作为药剂辅料的应用

本文综述了甲壳素这一天然多糖生化物质的性质及其在药物制剂方面的应用,尤其是其缓释、控释作用,借以说明该物质作为药剂辅料急待开发研制的重要性。     

用羧甲基甲壳素亲和层析提制溶菌酶

<正> 溶菌酶又称胞壁质酶,是细菌细胞壁的溶解酶,其作用的最适小分子底物为N-乙酰氨基葡萄糖(NAG)与N-乙酰氨基葡萄糖乳酸(NAM)交替的六糖。这结构与天然甲壳素(Chitin聚-2-乙酰氨基-2-脱氧-D-吡喃葡糖)相似,甲壳素的结构为:是溶菌酶的类似底物,能与溶菌酶形成酶-底物复合物。因此,可将甲壳素羧甲基     

甲壳素（chitin）、壳聚糖（chitosan）及其衍生物在医药方面的应用

甲壳素、壳聚糖是天然高分子聚合物，近年来随着对其研究的不断深入，甲壳素、壳聚糖的应用也日趋广泛。本文综述了甲壳素．壳聚糖及其衍生物在医药方面的应用；包括抗肿瘤，免疫抗菌与医用敷料等。     

甲壳素及其衍生物在医药敷料中的应用进展

甲壳素，又称甲壳质、几丁质，是天然多糖类高分子物质，化学名为β-1，4-2-乙酰氨基-2-脱氧-D-葡萄糖，分子式（C8H13NO5）a，不溶于水、稀酸、稀碱和一般有机溶剂，具有α、β、γ三种晶型，广泛存在于虾蟹壳、昆虫外壳、真菌细胞壁、植物细胞壁中。甲壳素经脱乙酰基后的产物称为壳聚糖，也称几丁聚糖、脱乙酰甲壳素、可溶性甲壳素、甲壳胺等。     

小儿健脾合剂澄清工艺研究

目的:考察甲壳素对小儿健脾合剂水提取液澄清效果。方法:采用L9(34)正交试验法优选最佳澄清工艺条件并检测自然沉降法、醇沉淀法和甲壳素澄清法后小儿健脾合剂的相对密度,总固体物质量分数。结果:最佳澄清工艺条件为(A3B2C1):清膏温度50℃,1%甲壳素盐酸溶液用量为3%,搅拌时间25min。甲壳素澄清法澄清前后相对密度、总固体物质量分数优于自然沉降法和乙醇沉淀法。结论:甲壳素澄清法工艺简单、澄清效果满意,适用于小儿健脾合剂的澄清。     

Chitin synthase 2 inhibitory activity of O-methyl pisiferic acid and 8,20-dihydroxy-9(11),13-abietadien-12-one, isolated from Chamaecyparis pisifera

In the course of search for potent chitin synthase inhibitors from plant extracts, the chitin synthase 2 inhibitors, O-methyl pisiferic acid and 8,20-dihydroxy-9(11),13-abietadien-12-one which have diterpene skeleton, were isolated from the leaves of Chamaecyparis pisifera. These compounds inhibited chitin synthase 2 of Saccharomyces cerevisiae with the IC50 values of 5.8 and 226.4 microM, respectively. Especially, O-methyl pisiferic acid showed 15.3-fold stronger inhibitory activity than polyoxin D (IC50=88.6 microM), a well-known chitin synthase inhibitor. These compounds exhibited weaker inhibitory activities against chitin synthase 1 than chitin synthase 2, whereas it showed no inhibitory activity for chitin synthase 3. The compound exhibited mixed competitive inhibition with respect to UDP-N-acetyl-D-glucosamine as substrate (Ki=5 microM). These results indicated that O-methyl pisiferic acid is a specific inhibitor of chitin synthase 2. The compound also inhibited chitin synthase 1 of Candida albicans, which represents analogues to chitin synthase 2 of S. cerevisiae, with an IC50 of 75.6 microM, which represents 1.8-fold weaker activity than that of polyoxin D. Although O-methyl pisiferic acid has been reported for antibacterial and insecticidal activities, the present study is the first report on its inhibitory activity against chitin synthase 2.     

The development of embolizing materials for chemo-embolization therapy of hepatocellular carcinoma

We developed chitin-containing cisplatin (CDDP) albumin microspheres (MS). We also investigated physical properties of MS in vitro, anti-tumor effect of MS in VX2 tumor model rabbits in vivo and clinical evaluation of MS. The CDDP contents, specific surface areas and yield of MS increased with an increase in the concentration of chitin. These findings suggest that accumulation of chitin on the surface of microsphere was the cause of expansion of the coated area as the concentration of chitin increased. In vitro CDDP releases decreased as the concentration of chitin increased. The initial burst effect of the drug was to be controlled by the increase of concentration of chitin. The chitin-containing CDDP microspheres showed similar CDDP release patterns irrespective of the concentration of chitin between 1 and 6 h after the administration of CDDP microspheres. After 6 h, the blood Pt levels increased with an increase in the concentration of CDDP microspheres suggesting a significant effect of the concentration of chitin on microsphere decomposability in vivo. Tumor growth rate was increasingly suppressed as the concentration of chitin increased. Clinical findings indicated that antitumor activity of chitin-containing CDDP albumin microspheres would have a chemoembolic effect by embolizing the hepatic artery. In the tumor and necrosis portions phagocytosis of microspheres by macrophage-like giant cell was shown. Consequently, the biocompatibility and decomposable properties of chitin-containing CDDP albumin microspheres were demonstrated.     

Sesquiterpene furan compound CJ-01, a novel chitin synthase 2 inhibitor from Chloranthus japonicus SIEB

A novel sesquiterpene furan compound CJ-01 was isolated from the methanol extract of the whole plant of Chloranthus japonicus SIEB. by monitoring the inhibitory activity of chitin synthase 2 from Saccharomyces cerevisiae. Based on spectroscopic analysis, the structure of compound CJ-01 was determined as 3,4,8a-trimethyl-4a,7,8,8a-tetrahydro-4a-naphto[2,3-b]furan-9-one. The compound inhibited chitin synthase 2 of Saccharomyces cerevisiae in a dose-dependent manner with an IC50 of 39.6 microg/ml, whereas it exhibited no inhibitory activities against chitin synthase 1 and 3 of S. cerevisiae up to 280 microg/ml. CJ-01 has 1.7-fold stronger inhibitory activity than polyoxin D (IC50=70 microg/ml), a well-known chitin synthase inhibitor. These results indicate that the compound is a specific inhibitor of chitin synthase 2 from S. cerevisiae. In addition, CJ-01 showed antifungal activities against various human and phytopathogenic fungi. Therefore, the compound might be an interesting lead to develop effective antifungal agents.     

甲壳质对氧自由基致人脐静脉内皮细胞损伤的保护作用

在培养的人脐静脉内皮细胞中观察了不同剂量的甲壳质对氧自由基损伤的内皮细胞培养上清液中丙二醛和乳酸脱氢酶含量的影响。结果表明,与损伤对照组相比,甲壳质保护组培养上清液中丙二醛和乳酸脱氢酶的含量均显著下降。提示甲壳质对氧自由基损伤的内皮细胞有一定的保护作用。     

Development of Coprocessed Chitin-Calcium Carbonate as Multifunctional Tablet Excipient for Direct Compression

Owing to the increasing interest in multifunctional excipients for tableting, coprocessing of individual excipients is regularly used to produce excipients of improved multifunctionality superior to individual excipients or their physical mix. The use of chitin as an excipient in tablet formulation is limited because of certain drawbacks such as poor flowability and low true density. The objective of this work is to improve these properties through coprocessing of chitin with calcium carbonate (CaCO₃) by precipitating CaCO₃ on chitin particles using different methods. In addition, optimization of the coprocessed chitin was carried out to improve the excipient's properties. Physicochemical (CaCO₃ content, true density, X-ray diffraction, infrared spectroscopy, and scanning electron microscopy) and functional testing (swelling force, flowability, tensile strength, deformation mechanism, and disintegration time) were used to characterize the coprocessed product. Results showed that the calcite CaCO₃ polymorph is precipitated on the chitin surface and that it interacts with chitin at carbonyl- and amide-group level. In addition, the coprocessed excipient has an improved true density and powder flowability, with CaCO₃ forming single layer on the chitin particles surface. Tableting studies showed that the coprocessed powder exhibited an intermediate deformation behavior between CaCO₃ (most brittle) and chitin (most plastic). Tablets showed acceptable tensile strength and rapid disintegration (2-4 s). These results show the potential use of coprocessed chitin-CaCO₃ as a multifunctional excipient for fast disintegration of tablets produced by direct compression.     

Inhibition of chitin synthases and antifungal activities by 2'-benzoyloxycinnamaldehyde from Pleuropterus ciliinervis and its derivatives

In the course of search for potent chitin synthase inhibitors from natural resources, a novel chitin synthases inhibitor, 2'-benzoyloxycinnamaldehyde (2'-BCA) (I), was isolated from the aerial parts of Pleuropterus ciliinervis NAKAI. 2'-BCA inhibited chitin synthase 1 and 2 of Saccharomyces cerevisiae with the IC50s of 54.9 and 70.8 microg/ml, respectively, whereas it exhibited no inhibitory activity for chitin synthase 3 up to 280 microg/ml. Its derivatives, 2'-chloro- (V) and 2(-bromo-cinnamaldehyde (VI), each showed 1.9 and 2.7-fold stronger inhibitory activities than 2'-BCA, with the IC50s of 37.2 and 26.6 microg/ml, respectively. Especially, the IC50 of compound VI against chitin synthase 2 represented 1.7-fold more potent inhibitory activity than polyoxin D, a well-known chitin synthase inhibitor. Furthermore, compounds V and VI showed potent antifungal activities against various fungi including human pathogenic fungi, with a particularly strong inhibitory activity against Cryptococcus neoformans (MIC = 16 microg/ml). Although the chemical synthesis of this compound has been reported, the present study is the first report to describe the isolation of 2'-BCA from natural resources and chitin synthases inhibitory activities of its derivatives. These results suggested that 2'-BCA and its derivatives can potentially serve as useful lead compounds for development of antifungal agents.     

Inhibition of chitin synthase 2 and antifungal activity of lignans from the stem bark of Lindera erythrocarpa

Potent chitin synthase 2 inhibitors, methyllinderone (1), linderone (2) and kanakugiol (3) were isolated from the stem bark of L. erythrocarpa Makino (Lauraceae). These compounds inhibited chitin synthase 2 with IC(50) values of 23.3, 21.4 and 23.8 microg/mL, respectively. Methyllinderone (1) and linderone (2) exhibited no inhibitory activities for chitin synthases 1 and 3 from S. cerevisiae, and chitin synthase 1 from Candida albicans up to the concentration of 280 microg/mL, while kanakugiol (3) exhibited very weak activity against chitin synthase 1 of C. albicans with an IC(50) of 160 microg/mL. All of the compounds showed moderate to weak antifungal activities against various pathogenic fungi (MIC: 8 - >128 microg/mL) including Cryptococcus neoformans, Aspergillus fumigatus, and Colletotrichum lagenarium. The results indicate that these compounds are specific inhibitors of chitin synthase 2 and can potentially serve as antifungal agents.