PEROXIDASE-MEDIATED BROMINATION OF UNSATURATED FATTY-ACIDS TO FORM BROMOHYDRINS

Eosinophil peroxidase and myeloperoxidase (MPO) catalyze the oxidation of bromide by hydrogen peroxide to produce hypobromous acid (HOBr). H ypochlorous acid, which is also generated by MPO, reacts with unsatura ted fatty acids to form chlorohydrins. In this study the equivalent re action of HOBr, produced from MPO, bromide, and hydrogen peroxide, wit h oleic (18:1), linoleic (18:2), and arachidonic (20:4) acids has been investigated, Thin-layer chromatography detected one major product of higher polarity than the unmodified fatty acids and additional more p olar products with the polyunsaturated fatty acids, Similar results we re observed with N-bromosuccinimide-derived HOBr, Gas chromatography-m ass spectrometry (GO-MS) and electrospray MS identified the major prod ucts of 18:1 as the isomeric 9,10-bromohydrins based on retention time and mass spectrometric isotope and fragmentation patterns, The produc ts of 18:2 and 20:4 were too unstable for analysis by GC-MS. Electrosp ray MS identified the mono- and bisbromohydrins formed from 18:2 and 2 0:4 based on mass/charge ratios of the molecular ions and the presence of bromine isotope patterns, Other oxidation products not containing bromine, such as dihydroxy derivatives, were detected as well, Fatty a cid bromohydrins could contribute to the antimicrobial activity and in flammatory tissue damage by eosinophils and neutrophils, and could pot entially be useful specific markers for HOBr production in vivo. (C) 1 996 Academic Press, Inc.