title: Catechol is the major product of salicylate hydroxylation in 1-methyl-4-phenylpyridinium ion treated rats.
abstract: Salicylate hydroxylation using hydroxyl free radicals results into formation of 2,3-dihydroxybenzoic acid, 2,5-dihydroxybenzoic acid and catechol. Inspite of the fact that in vitro experiments have shown that catechol is a minor product, we have shown by these in vivo studies that it is a substantial product. Since catechol as well as 2,3-dihydroxybenzoic acid have not been found to be produced enzymatically from salicylates, they appear useful as in vivo indicators for monitoring hydroxyl free radicals. Administration of 1-methyl-4-phenylpyridinium ion (MPP+) to rat striatum using microdialysis results into the formation of hydroxyl radicals. Salicylate perfusion enables the estimation of the three derivatives cited above. They increased significantly after MPP+ administration in comparison to the baseline values, with catechol being the most significant. The maximum amounts were achieved 60 min after MPP+ administration, and the mean percentage increase at this time point were 83.1% for 2,3-DBA (n = 6, P = 0.005), 81.25% for 2,5-DBA (n = 6, P = 0.011) and 1228.8% for catechol (n = 4, p = 0.00008). MPP+ caused substantial decrease of dopamine metabolites. Dihydroxyphenylacetic acid decreased to 13% and homovanillic acid to 11.4%. We conclude that catechol is an important indicator of hydroxyl free radical formation in this animal model which is well suited to study the role of free radicals in Parkinsonism.
authors.affiliation: Katholieke Universiteit Leuven, Laboratorium voor Farmacotechnologie en Biofarmacie, Belgium.
authors.forename: E
authors.initials: E
authors.lastname: Sam
authors.forename: S
authors.initials: S
authors.lastname: Sarre
authors.forename: Y
authors.initials: Y
authors.lastname: Michotte
authors.forename: N
authors.initials: N
authors.lastname: Verbeke
mesh_terms: D015655:1-Methyl-4-phenylpyridinium / Q000494:pharmacology*; D000818:Animals; D002396:Catechols / Q000378:metabolism*; D004195:Disease Models, Animal; D017665:Hydroxyl Radical; D006900:Hydroxylation; D008297:Male; D017551:Microdialysis; D010300:Parkinson Disease / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D012459:Salicylates / Q000378:metabolism*; D014793:Visual Cortex / Q000187:drug effects* / Q000378:metabolism
chemical_list: D002396:Catechols; D012459:Salicylates; D017665:Hydroxyl Radical; C034221:catechol; D015655:1-Methyl-4-phenylpyridinium