Polypyrroles as Antioxidants: Kinetic Studies on Reactions of Bilirubin and Biliverdin Dimethyl Esters and Synthetic Model Compounds with Peroxyl Radicals in Solution. Chemical Calculations on Selected Typical Structures
作者:Leonid L. Chepelev、Cory S. Beshara、Patricia D. MacLean、Gillian L. Hatfield、Amy A. Rand、Alison Thompson、James S. Wright、L. Ross C. Barclay
DOI:10.1021/jo051359e
日期:2006.1.1
Rate constants for hydrogen-atom transfer (HAT) from bilirubin dimethyl ester (BRDE) and biliverdin dimethyl ester (BVDE) to peroxyl radicals during inhibited autoxidation of styrene initiated by azo-bisisobutyronitrile (AIBN) were kinh(BRDE) = 22.5 × 104 and kinh(BVDE) = 10.2 × 104 M-1 s-1, and the stoichiometric factors (n) were 2.0 and 2.7, respectively. A synthetic tetrapyrrole (bis(dipyrromethene))
在偶氮-双异丁腈(AIBN)引发的苯乙烯自抑制氧化过程中,氢胆素从胆红素二甲基酯(BRDE)和胆绿素二甲酯(BVDE)到过氧自由基的转移速率常数为k inh(BRDE)= 22.5×10 4和k inh(BVDE)= 10.2×10 4 M - 1 s - 1,化学计量系数(n)分别为2.0和2.7。合成四吡咯含有(双(二吡咯亚甲基))α -中央(2,2' )CH 2联动给ķ INH = 39.9×10 4中号-1 s - 1,n = 2.3,而β-连接的(3,3')异构体不是活性抗氧化剂。合成了几个二吡啶酮,作为胆红素和胆绿素的两个外杂环的模拟物。在每个环中含有NH基的二吡啶酮是活性抗氧化剂,而缺乏两个这样的“游离” NH基的二吡啶酮(如N-CH 3吡啶酮和二嘧啶)则没有抗氧化活性。总的来说,相对ķ INH值相比,这些酚类抗氧化剂,2,6-二-叔丁基-4-甲氧基苯酚(DBHA)和2,6-二-叔丁基-4-甲基苯酚(BHT)是2