3-hydroxyanthranilic acid-derived compounds formed through electrochemicaloxidation

3-Hydroxyanthranilic acid (3-HAA)-derived oxidation products were analyzed using high-performance liquid chromatography with an electrochemical reacto r and diode array detection and high-performance liquid chromatography with an electrochemical reactor and UV detection coupled with mass spectrometry . In addition to 3-HAA dimers such as cinnabarinic acid (CA), 6-amino-3-[(2 -carboxy-6-hydroxyphenyl)amino]-2,5-dioxo-1,3-cyclohexadiene-1-carboxylic a cid and 4,7-diamino-8-hydroxy-6H-dibenzo[a,d]pyran-6-one-3-carboxylic acid, a 3-HAA trimer and a 3-HAA tetramer were also detected and identified base d on their electrospray ionization mass spectra and their UV-visible spectr a. These five oxidation products were also detected on the elution profiles of high-performance liquid chromatography-diode array detection analyses f or the reaction mixtures of the auto-oxidation of 3-HAA, of 3-HAA with pota ssium ferricyanide, of 3-HAA with horseradish peroxidase and hydrogen perox ide, and of 3-HAA with superoxide dismutase (SOD). 4,7-Diamino-8-hydroxy-6H -dibenzo[a,d]pyran-6-one-3-carboxylic acid was predominant in the auto-oxid ation, in the reaction of 3-HAA with horseradish peroxidase and hydrogen pe roxide, and in the electrochemical oxidation of 3-HAA at an applied potenti al of 0.0 V. On the other hand, CA, the 3-HAA trimer and the 3-HAA tetramer were predominant in the reaction of 3-HAA with K-3[Fe(CN)(6)] and in the e lectrochemical oxidation of 3-HAA at an applied potential of 1.0 V. (C) 199 9 Elsevier Science B.V. All rights reserved.