The Effect of Hydroxycinnamic Acids on Oxy-Radical Generating Iodide-Hydrogen Peroxide Reaction

Abstract

The influence of hydroxycinnamic acids (HCA) on the oxy-radical generated system, potassium iodide/hydrogen peroxide, was investigated through the enhancement of triiodide (I-3(-)) yield. Caffeic acid, clilorogenic acid, and p-coumaric acid were used as typical representatives of HCA. A linear correlation, with positive slopes, was found between absorption maximum of I-3(-) at 351 urn and HCA concentration in all cases. The magnitude of enhanced I-3(-) production was found to increase in the following order: p-coumaric acid LT chlorogenic acid LT = caffeic acid. A reaction mechanism, which includes negative influence of oxygen-centered free radicals on the I-3(-) yield, was proposed. The enhanced production of I-3(-) by HCA is attributed to their radical scavenging activity. Supported by literature data, results obtained in this study have showed the correlation between radical scavenging activities of HCA and their ability to enhanced I-3(-) generation.