How many peroxyl radicals can be scavenged by hydroxyl-substituted Schiff bases in the oxidation of linoleic acid?

摘要

Eleven hydroxyl-substituted Schiff bases (SchOHs) were synthesized by the reaction between hydroxyl-substituted benzaldehydes and hydroxyl-substituted anilines, and their antioxidant effects on the oxidation of linoleic acid (dissolved in sodium dodecyl sulfate micelle) induced by 2,2'-azobis(2-amidinopropane hydrochloride) (AAPH) were investigated. The relationships between the period of the oxidation inhibited by SchOHs (t(inh)) and their concentrations ([SchOHs]) were measured firstly, and then treated by a chemical kinetic equation, t(inh) = (n/R-i)[SchOH], to obtain the number (n) of the oxidative chains terminated by one molecule of SchOH. Therefore, the antioxidant activities of SchOHs can be expressed quantitatively by the n value. Finally, the spin-densities (SD) on O atom in the radical of SchOH (SchO(center dot)) were calculated by quantum chemical method, and, to some extent, SD provided an explanation to the difference of the antioxidant effects among various SchOH. Therefore, the obtained results provided an attempt to bridge the kinetic measurement and quantum calculation in the study on the property of an antioxidant.