Evidence for a possible role of 3-hydroxyanthranilic acid as an antioxidant

The reactions of 3-hydroxyanthranilic acid (3-OHAA) with N*(3) NO3*, NO*, CCl3O*(2) and OH* radicals were examined using a pulse radiolysis technique mainly at pH 7. The bimolecular electron transfer from secondary one-electron oxidants results in the formation of anilino radical (lambda(max) similar to 380 nm). The rate constant for the reaction of N-3* radical with 3-OHAA at pH 7 was found to be 6.3 X 10(9) dM(3) Mol(-1) s(-1). It was observed that the 3-OHAA reacts with oxygen centered radicals. The repair rate constant for the electron transfer reaction from 3-OHAA to guanosine radical and chlorpromazine cation radical was also examined using a pulse radiolysis technique. Kinetic studies indicate that 3-OHAA may act as an antioxidant to repair free-radical damage to above mentioned biologically important compounds. The rate constants of electron transfer from the 3-OHAA to the guanosine and chlorpromazine radicals were determined. The one-electron reduction potential for 3-OHAA radical was found to be 0.53 +/- 0.06 V versus NHE. Copyright (C) 2008 John Wiley & Sons, Ltd.