Kinetic Model for the Antiradical Activity of the Isolated <i>p</i>-Catechol Group in Flavanone Type Structures Using the Free Stable Radical 2,2-Diphenyl-1-picrylhydrazyl as the Antiradical Probe
作者:José M. Sendra、Enrique Sentandreu、José L. Navarro
DOI:10.1021/jf070689s
日期:2007.7.1
acetonitrile the reduction curves completely lacked the slow kinetics step. From the results, a kinetic model for the reaction of reduction of the DPPH* by the isolated p-catechol group in flavanone type structures is proposed. According to this model, the p-catechol group rapidly transfers two hydrogen atoms to DPPH*, through a fast rate constant k1, yielding the corresponding o-quinone. Then, the intermediate
三种溶剂中含有分离的对儿茶酚基团的黄烷酮(紫杉醇,二十烷三醇,分光光度法和液相质谱法测定了反应混合物质谱的时间演化。在含酒精的溶剂中,还原曲线由最初的短暂但快速的动力学步骤组成,随后是较长的缓慢的动力学步骤;相反,在乙腈中,还原曲线完全缺少慢动力学步骤。根据结果,提出了在黄烷酮类结构中分离的对-邻苯二酚基团还原DPPH *的反应的动力学模型。根据这个模型,对苯二酚基团通过快速速率常数k1将两个氢原子迅速转移至DPPH *,得到相应的邻醌。然后,中间体邻醌通过缓慢的速率常数k 2与醇溶剂形成加合物,并再生对儿茶酚基团。再生的对苯二酚基团通过快速速率常数k3减少了额外的DPPH *,生成了相应的邻苯二酚,邻苯二酚可与溶剂形成新的加合物以再生对苯二酚基团,依此类推。从动力学模型中,导出了两个非常明确的动力学方程式,它们非常适合从所进行的所有实验中从所有被测化合物中获得的实验数据点,从而可以准