Hydroxyl radical induced oxidation of 3-methoxy-4-hydroxy cinnamic acid (ferulic acid)

Hydroxyl radical reaction of 3-methoxy-4-hydroxy cinnamic acid (ferulic aci d) produced the (OH)-O-.-radical adducts. A part of these radical adducts u ndergo water elimination to finally yield phenoxyl radicals and the process was found to be base catalysed. Phenoxyl radical of ferulic acid was furth er identified by following its reaction with more specific oxidising radica ls, e.g. azide (N-3(.)) and Cl-2(.-) in the pH range from 2.5 to 9. The phe noxyl radicals produced by one-electron oxidation did not possess any pK(a) in this pH range. The one-electron reduction potential for the formation o f the phenoxyl radical was determined after achieving electron transfer equ ilibrium between the two couples involving the phenoxyl radical/phenol and phenothiazine radical cation/phenothiazine. Scavenging ability of the pheno l toward NO2. radical was evaluated.