Antifungal Activity of Quaternized Carboxymethyl Chitosan

Quaternized carboxymethyl chitosan (QCMC) were synthesized and their antifungal activities against Alternaria Solani (A. Solani) and Physalospora piricola Nose (P. piricola Nose) were investigated. The results indicated that the quaternized carboxymethyl chitosan derivatives had better inhibitory effects than CMC, and the antifungal activities should be affected by the cation in these compounds.

Preparation, characterization and antifungal properties of 2-(alpha-arylamino phosphonate)-chitosan

In this paper, 20 kinds of different 2-(alpha-arylamino phosphonate)-chitosan (2-alpha-AAPCS) were prepared by different Schiff bases of chitosan (CS) reacted with di-alkyl phosphite in benzene solution. The structures of the derivatives (2-alpha-AAPCS) were characterized by FT-IR spectroscopy and elemental analysis. In addition, the antifungal activities of the derivatives against four kinds of fungi were evaluated in the experiment. The results indicated that all the prepared 2-alpha-AAPCS had a significant inhibiting effect on the investigated fungi when the derivatives concentration ranged from 50 to 500 mu g mL(-1). Furthermore, the antifungal activities of the derivatives increased with increasing the molecular weight and concentration. And the antifungal activities of the derivatives were affected by their dimensional effect and charge density. Besides, the rule and mechanism of the antifungal activities of them were discussed in this paper. (C) 2009 Elsevier B.V. All rights reserved.

Antifungal properties of Schiff bases of chitosan, N-substituted chitosan and quaternized chitosan

Schiff bases of chitosan, N-substituted chitosan, and quaternized chitosan were synthesized and their antifungal properties were analyzed against Botrytis cinerea Pers. (B. cinerea pers.) and Colletotrichum lagenarium (Pass) Ell.et halst (C. lagenarium (Pass) Ell.et halst) based on the method of D. Jasso de Rodriguez and co-workers. The results showed that quaternized chitosan had better inhibitory properties than chitosan, Schiff bases of chitosan, and N-substituted chitosan. (c) 2007 Elsevier Ltd. All rights reserved.

The influence of molecular weight of quaternized chitosan on antifungal activity

Quaternized chitosan derivatives with different molecular weights were synthesized in the laboratory. Subsequent experiments were conducted to test their antifungal activities against Botrytis cinerea Pers. (B. cinerea pers.) and Colletotrichum lagenarium (Pass) Ell.et halst (C. lagenarium (Pass) EII.et halst). Our results indicate that quaternized chitosan derivatives have stronger antifungal activities than chitosan. Furthermore, quaternized chitosan derivatives with high molecular weight are shown to have even stronger antifungal activities than those with low molecular weight. (c) 2007 Published by Elsevier Ltd.

The influence of the cationic of quaternized chitosan on antifungal activity

Quatemized chitosan: N-(2-hydroxyl-phenyl)-NN-dimethyl chitosan (NHPDCS), N-(5-chloro-2-hydroxyl-phenyl)-NN-dimethyl chitosan (NCHPDCS), N-(2-hydroxyl-5-nitro-phenyl)-NN-dimethyl chitosan (NHNPDCS) and N-(5-bromic-2-hydroxyl-phenyl)-NN-dimethyI chitosan (NBHPDCS) were synthesized and their antifungal activities against Botrytis cinerea Pers. (B. cinerea Pers.) and Colletotrichum lagenarium (Pass) Ell.et halst (C. lagenarium (Pass) Ellet halst) were investigated. The results indicated that the quaternized chitosan derivatives had better inhibitory effects than chitosan, and the antifungal activities should be affected by the cation in these compounds. (C) 2007 Elsevier B.V. All rights reserved.

Synthesis and antifungal properties of sulfanilamide derivatives of chitosan

Sulfanilamide derivatives of chitosan (2-(4-acetamido-2-sulfanimide)-chitosan (HSACS, LSACS), 2-(4-acetamido-2-sulfanimide)-6-sulfo-chitosan (HSACSS, LSACSS) and 2-(4-acetamido-2-sulfanimide)-6-carboxymethyl-chitosan (HSACMCS, LSACMCS)) were prepared using different molecular weights of chitosan (CS), carboxymethyl chitosan (CMCS) and chitosan sulfates (CSS) reacted with 4-acetamidobenzene sulfonyl chloride in dimethylsulfoxide solution. The structures of the derivatives were characterized by FT-IR spectroscopy and elemental analysis, which showed that the substitution degree of sulfanilamide group of HSACS, HSACSS, HSACMCS, LSACS, LSACSS and LSACMCS were 0.623, 0.492, 0.515, 0.576, 0.463 and 0.477, respectively. The solubility of the derivatives (pH < 7.5) was higher than that of chitosan (pH < 6.5). The antifungal activities of the derivatives against Aiternaria solani and Phomopsis asparagi were evaluated based on the method of Jasso et al. in the experiment. The results indicated that all the prepared sulfanilamide derivatives had a significant inhibiting effect on the investigated fungi in the polymer concentration range from 50 to 500 mu g mL(-1). The antifungal activities of the derivatives increased with increasing the molecular weight, concentration or the substitution degree. The sulfanilamide derivatives of CS, CMCS and CSS show stronger antifungal activities than CS, CMCS and CSS. (C) 2007 Elsevier Ltd. All rights reserved.

Novel derivatives of chitosan and their antifungal activities in vitro

Three kinds of Schiff bases of carboxymethyl chitosan (CMCTS) were prepared, and their antifungal activities were assessed according to Jasso de Rodriguez's method. The results indicated that 2-(2-hydroxybenzylideneamino)-6-carboxymethylchitosan (HNCMCTS) and 2-(5-chloro-2-hydroxybenzylideneamino)-6-carboxymethylchitosan (HCCMCTS) had better inhibitory effects than those of chitosan or CMCTS against Fusarium oxysporium f. sp. vasinfectum, Alternaria solani, and Valsa mali. (c) 2005 Elsevier Ltd. All rights reserved.

Synthesis and QSAR studies of novel triazole compounds containing thioamide as potential antifungal agents

Eighteen novel triazole compounds containing thioamide were designed and synthesized. Their structures were confirmed by elemental analysis, H-1 NMR, IR, and MS. The title compounds exhibited certain antifungal activity. And the geometry structures of the title compounds were optimized by means of the density functional theory (DFT) method at B3LYP/6-31G* level. The quantitative structure-activity relationship (QSAR) of the title compounds was systematically investigated. A correlative equation between FA and DELH, V was well established by using the multiple linear regression (MLR). (c) 2006 Elsevier Ltd. All rights reserved.

杜仲抗真菌蛋白晶体生长的原子力显微成像研究—快速生长与晶面生长速率

杜仲抗真菌蛋白(Eucommiaantifungalprotein,EAFP)的单晶体具有在几小时内就可长大的快速生长特性.用原子力显微成像(atomicforcemicroscope,AFM)技术,原位实时观测了EAFP单斜晶体生长过程中的｛10 0｝表面形貌动态变化,并分别在不同的过饱和度下测量了其生长速率.结果表明,EAFP晶体生长的速率与蛋白质溶液的过饱和度相关,在过饱和度高时(σ =1 78)晶面生长极快;在中等过饱和度(σ =1 5)下,其晶面台阶的生长速率沿b,c方向分别为 12nm/s和 2 4 2nm/s,比溶菌酶生长速率(6～ 7nm/s)快很多;在蛋白质浓度很低的情况下,其生长速率仍与其他蛋白质相当.EAFP晶体快速生长可能与该分子尺寸较小,内部结构紧凑,分子骨架呈刚性和分子表面性质等其固有特性密切相关.沉淀剂浓度对EAFP晶体生长也有影响.过饱和度很低时,提高沉淀剂浓度会干扰晶体生长.

杜仲抗真菌蛋白(EAFP)晶体动态生长研究

杜仲抗真菌蛋白(eucommia antifungal protein,EAFP),含有41个氨基酸残基,其中有10个半胱氨酸,半胱氨酸间形成的二硫桥键使分子构象很稳定.EAFP的晶体属单斜晶系,空间群为P21,晶胞参数为:a=1.9085nm,b=2.3225nm,c=3.0854nm10-6,β=98.64,分子量为4158.9.EAFP晶体生长速度快,对X射线的衍射能力强,很值得研究其生长的机理.利用原子力显微镜(AFM)对EAFP晶体的{100}面进行动态的生长研究,发现在中低过饱和度下主要以各向异性的单双链螺旋位错的生长模式进行生长,详细研究了这种螺旋的形成机制,并探讨了其结构基础.

用AFM研究杜仲抗真菌蛋白的晶体生长

随着后基因组时代的到来以及蛋白质组学研究的深入开展,研究蛋白质晶体生长成为生物化学和结构生物学领域一个广泛关注的课题。通过使用原子力显微镜(Atomic Force Microscope,简称AFM)对杜仲抗真菌蛋白(eucommia antifungal protein,简称EAFP)的晶体在有母液存在下原位实时动态地进行了晶面生长观察。研究结果表明:不同过饱和度对EAFP晶体生长形貌的影响较大,较高的过饱和度下生长很快,生长台阶密度高,较高的过饱和度下主要进行各向异性二维台阶的发生、发展,较低的过饱和度下主要采用螺旋位错的生长方式,当过饱和度极低时生长缓慢,且晶体表面有很多小孔存在,晶面生长很不完整;还对不同过饱和度下晶体生长速率进行了定量的测量,也反映了过饱和度对EAFP晶体生长的影响;同时对在AFM观察过程中由探针的扫描速度和方向对表面形貌的影响进行了讨论。

商陆抗真菌蛋白的基因克隆及其应用

商陆种子的7kD多肽被鉴定为一种抗真菌多肽，命名为PAFP（pokeweed antifungal protein）。它抑制Trichoderma viride, Fusatium及其它一些病原真菌的生长。本文构建了cDNA文库，而后从库中筛选和克隆PAFP基因。PAFP的编码序列－－201bp的DNA片段被扩增并插入pBluescript SK+载体。经酶切图谱分析和核苷酸顺序测定之后，这个片段与35S启动子连接并重组于双元载体pBin 19。此表达载体质粒转入农杆菌LBA 4404供转化植物之用。通过农杆菌介导的对西瓜的转化，所采用的基因还包括报告基因GUS和Bar，以及一种来自大麦的抗真菌蛋白的基因。以PCR扩增，GUS与NPT II活性检测，以及Southern杂交对转基因植物进行鉴定。

枯草芽孢杆菌生物学特性及其与稻瘟病菌互作的蛋白质组学研究

枯草芽孢杆菌（Bacillus subtilis）是革兰氏阳性细菌研究的模式菌株，为重要的生防菌剂。本论文以枯草芽孢杆菌ATCC6051作对照，首次对新型菌株KB-1111和KB-1122进行了生物学特性、生防潜力以及与水稻稻瘟病致病菌互作的蛋白质组学研究。 形态学观察表明，菌株KB-1111和KB-1122在细胞形态、芽孢的大小、运动性、菌落褶皱和色素的生成等方面与菌株ATCC6051相似，具有枯草芽孢杆菌的典型特征。生理生化测定以及对多种碳源的利用结果显示，三个菌株大部分指标检测结果相同，只在几个方面等存在差异。 体外平板对峙抑菌试验说明，枯草芽孢杆菌ATCC6051、KB-1111和KB-1122对8种作物、果蔬代表性病害致病真菌具有明显的拮抗效果。其中，菌株KB-1122的广谱抗真菌活性优于KB-1111，而KB-1111又强于对照菌株ATCC6051，尤其是对稻瘟病（M. grisea P131）和蔬菜菌核病（S. sclerotiorum）显现出强烈的抑制作用，具备生防拮抗菌的优秀性能。 比较蛋白质组学分析结果表明，液体悬浮培养枯草芽孢杆菌KB-1111、KB-1122二维蛋白质组表达谱至少有11个胞内蛋白和10个胞外蛋白出现丰度差异。其中，菌株KB-1122中胁迫或逆境反应相关ATP酶、顺乌头酸水合酶和alpha-淀粉酶前体在细胞内蛋白质组，以及分泌型蛋白―内切葡聚糖酶在胞外蛋白质组中的高丰度表达可能与菌株KB-1122的优势拮抗能力相关。 将对数生长期的枯草芽孢杆菌KB-1122与菌丝丰富期的稻瘟病菌P131悬浮混合共培养发现，在24小时的共培养过程中，稻瘟病菌P131菌丝体及芽管经历了致变、破裂、细胞质溢出直至菌丝体崩溃等一系列变化，枯草芽孢杆菌KB-1122表现出强烈的拮抗效应。差异显示蛋白质组学研究表明，共培养菌体蛋白质组至少有39个蛋白点丰度发生显著变化，其中33个蛋白点得到成功鉴定，包括12个上调蛋白和21个下调蛋白。根据鉴定结果分析，这些上调的蛋白质全部来源于枯草芽孢杆菌，而下调的蛋白全部属于稻瘟病菌。共培养过程中的培养液蛋白质组至少有20个蛋白点丰度发生显著变化，其中18个蛋白点得到成功鉴定。根据以上分析结果初步认为，3-磷酸甘油醛脱氢酶、丝氨酸蛋白激酶和内切葡聚糖酶在枯草芽孢杆菌KB-1122与稻瘟病菌P131相互作用的过程中可能是B. subtilis KB-1122发挥抗真菌活性的关键性蛋白。