Influence of Chlorine Substitution on the Hydrolytic Stability of Biaryl Ether Nucleoside Adducts Produced by Phenolic Toxins
作者:Michael S. Kuska、Mohadeseh Majdi Yazdi、Aaron A. Witham、Heidi A. Dahlmann、Shana J. Sturla、Stacey D. Wetmore、Richard A. Manderville
DOI:10.1021/jo401122j
日期:2013.7.19
kinetic study is reported for the acid-catalyzed hydrolysis of oxygen (O)-linked biaryl ether 8-2′-deoxyguanosine (dG) adducts produced by phenolic toxins following metabolism into phenoxyl radical intermediates. Strikingly, the reaction rate of hydrolysis at pH 1 decreases as electron-withdrawing chlorine (Cl) substituents are added to the phenoxyl ring. The Hammett plot for hydrolysis at pH 1 shows a linear
动力学研究报道了由酚类毒素代谢成苯氧基自由基中间体后,由氧(O)连接的联芳基醚8-2'-脱氧鸟苷(dG)加合物的酸催化水解。令人惊讶的是,随着吸电子的氯(Cl)取代基被添加到苯氧基环中,在pH 1下的水解反应速率降低。在pH哈米特情节进行水解1示出了具有ρ的线性负斜率X = -0.65,这意味着增加氯取代通过降低Ñ减少水解速率7碱度。分光光度滴定法可提供N 7 H + p K a未取代的加合物8-苯氧基-dG(Ph-O-dG)的数值为1.1。模型吡啶化合物表明,对于4-Cl-Ph-O-dG和2,6-二氯-Ph-O-dG(DCP-O-dG),N 7 H + p K a值分别为0.92和0.37。密度泛函理论(DFT)的计算也突出了8-苯氧基取代基降低N 7碱性的能力,并预测了水中高度氯化的O-连接的8-dG加合物对N 3-质子化的偏好。这些计算也为O的水解反应性提供了理论依据如电喷雾质谱法(