Hydroxylation of salicylate by microsomal fractions and cytochrome P-450. Lack of production of 2,3-dihydroxybenzoate unless hydroxyl radical formation is permitted

摘要: Attack by hydroxyl radicals (.OH) upon salicylate (2-hydroxybenzoate) leads to formation of both 2,3-dihydroxybenzoate (2,3-DHB) and 2,5-dihydroxybenzoate (gentisate, 2,5-DHB). It has been suggested that 2,3-DHB from is a means monitoring .OH formation. Production 2,5-DHB liver microsomal fractions isoforms cytochrome P-450 was investigated. Liver microsomes prepared variously treated rats rabbits catalysed the but not 2,3-DHB. Formation inhibited CO, metyrapone SKF-525A, scavengers mannitol formate or iron chelator desferrioxamine. Purified P-450s IIE1, IIB4 IA2 rabbit microsomes, reconstituted together with NADPH-cytochrome reductase, led equal amounts in reactions were almost completely formate. Addition Fe3+/EDTA either membranes containing caused approximately 2,5-DHB, consistent an .OH-dependent attack on salicylate. The data indicate system catalyses hydroxylation Hence measurement might provide Care must be taken studies substrate systems avoid artefacts resulting generation.