Fungal modification of the hydroxyl radical detector coumarin-3-carboxylic acid

The feasibility of using coumarin-3-carboxylic acid (3-CCA) for detection of hydroxyl radicals in pure cultures of wood-decaying fungi was tested. Fungi were incubated on a 3-CCA-containing medium. The transformation of 3-CCA to the fluorescent hydroxyl radical detector substance 7-hydroxycoumarin-3-carboxylic acid and other compounds was studied by chromatographic and spectroscopic techniques. During incubation of all tested fungi, a small fraction of the 3-CCA was hydroxylated to 7-hydroxycoumarin-3-carboxylic acid and a major fraction of the 3-CCA was metabolized by fungi to 2-(2-hydroxybenzyl)malonic acid. In most cultures the concentration of 3-CCA was below detection limit at the end of incubation. The fungal metabolism was suggested to be involved in the formation of 2-(2-hydroxybenzvl)malonic acid from 3-CCA, consequently making this method of hydroxyl radical detection less suitable to use on cultures of wood-decaying fungi. (C) 2003 Federation of European Microbiological Societies. Published by Elsevier B.V. All rights reserved.