The antioxidant activity of 2-(4(or 2)-hydroxyl-5-chloride-1,3-benzene-di-sulfanimide)-chitosan

Chitosan (CS) with two different molecular weights was modified by reacting with 4-hydroxyl-5-chloride-1,3-benzene-disulfo-chloride or 2-hydroxyl-5-chloride-1,3-benzene-disulfo-chloride to give new 2-(4(or 2)-hydroxyl-5-chloride-1,3-benzene-di-sulfanimide)-chitosan (2-HCBSAHCS, 2-HCBSALCS, 4-HCBSAHCS, 4-HCBSALCS). The structure of the derivatives was characterized by FT-IR and C-13 NMR spectroscopy. The antioxidant activities of the derivatives were investigated employing various established systems, such as hydroxyl radical ((OH)-O-center dot)/superoxide anion (O-2(radical anion)) scavenging/reducing power and chelating activity. All the derivatives showed stronger scavenging activity on hydroxyl radical than chitosan and ascorbic acid (Vc), and IC50 of 4-HCBSAHCS, 4-HCBSALCS, 2-HCBSAHCS and 2-HCBSALCS was 0.334, 0.302, 0.442, 0.346 mg/mL, respectively. The inhibitory activities of the derivatives toward superoxide radical by the PMS-NADH system were strong. The results showed that the superoxide radical scavenging effect of 2-(4(or 2)-hydroxyl-5-chloride-1,3-benzene-disulfanimide)-chitosan was higher than chitosan. The derivatives had obviously reducing power and slight chelating activity. The data obtained in in vitro models clearly establish the antioxidant potency of 2-(4(or 2)-hydroxyl-5-chloride-1,3-benzene-disulfanimide)-chitosan. (C) 2007 Elsevier Masson SAS. All rights reserved.

西洋参多糖PPQI-1～4的分离和表征

为研究生物活性西洋参多糖的性质 ,采取热水提取乙醇分级沉淀、葡聚糖凝胶分离等手段从西洋参根中分得 4个纯多糖 (PPQI- 1～ 4)。基质辅助激光解吸电离质谱 (MAL DI- MS)测定分子量 ,乙酰化衍生结合GC分析测定糖组成。甲基化结合 GC- MS分析测定糖苷键连接位点。结果表明 ,这 4个多糖化合物都是杂多糖 ,分别由不同比例的阿拉伯糖、半乳糖、葡萄糖、糖醛酸组成 ,糖醛酸含量为 30 %～ 6 0 % ,分子量范围 2～ 7万

单分散的还原态和中间氧化态聚苯胺齐聚物的合成与紫外光谱研究

提出了一条合成苯胺齐聚物的新路线 :由高氧化态的苯胺四聚体与二苯胺或 N-苯基 - 1,4 -对苯二胺反应合成苯基封端的苯胺五聚体和六聚体 ,用红外、质谱、核磁共振、基底辅助激光解吸质谱 (MAL DI- MS)进行了表征 .提出一条可能的机理 ,即高氧化态的苯胺四聚体与二苯胺或N -苯基 - 1,4 -对苯二胺在酸性溶液中混合时 ,四聚体、二苯胺和 N -苯基 - 1,4 -对苯二胺的分子中均形成阳离子自由基 ,四聚体的阳离子自由基与后二者的阳离子自由基耦合形成苯胺五聚体和六聚体 .还原态的苯胺齐聚物氧化成中间氧化态的苯胺齐聚物 ,使用硫酸铵和六水和三氯化铁等氧化剂能打断苯胺五聚体和六聚体的分子链 .实验发现 ,氧化银是将还原态苯胺齐聚物氧化成中间氧化态的齐聚物的最好的氧化剂 .用紫外可见光谱对中间氧化态的五聚体和六聚体进行了研究 ,对其分子中醌环的数目进行了讨论