Inhibition of peroxynitrite dependent tyrosine nitration by hydroxycinnamates: nitration or electron donation?
Peroxynitrite is a cytotoxic species generated by the reaction between superoxide and nitric oxide. In this study the ability of hydroxycinnamate antioxidants to decrease peroxynitrite-mediated nitration of tyrosine was investigated. The results obtained show that all compounds were able to inhibit nitration of tyrosine. The potency of inhibitory activity was in the order; caffeic acid > or = chlorogenic acid > or = ferulic acid > p-coumaric acid > ocoumaric acid > m-coumaric acid. Trolox, which was included in the study for comparative purposes, had an activity between that of ferulic acid and p-coumaric acid. The data obtained suggest that hydroxycinnamates can act by one of two possible mechanisms: preferential nitration for monophenolates and electron donation by catecholates.
Pannala
A S
AS
International Antioxidant Research Centre, Department of Pharmacy, King's College, University of London, Chelsea, UK.
Razaq
R
R
Halliwell
B
B
Singh
S
S
Rice-Evans
C A
CA
D000975:Antioxidants / Q000494:pharmacology*; D002109:Caffeic Acids / Q000494:pharmacology; D002726:Chlorogenic Acid / Q000494:pharmacology; D002839:Chromans / Q000494:pharmacology; D002851:Chromatography, High Pressure Liquid; D003373:Coumaric Acids / Q000494:pharmacology*; D016166:Free Radical Scavengers; D005609:Free Radicals; D009566:Nitrates / Q000737:chemistry* / Q000494:pharmacology*; D013053:Spectrophotometry; D014443:Tyrosine / Q000031:analogs & derivatives / Q000737:chemistry*
D000975:Antioxidants; D002109:Caffeic Acids; D002839:Chromans; D003373:Coumaric Acids; D016166:Free Radical Scavengers; D005609:Free Radicals; D009566:Nitrates; C039642:peroxynitric acid; D002726:Chlorogenic Acid; C002744:3-nitrotyrosine; D014443:Tyrosine; C004999:ferulic acid; C010643:6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid; C040048:caffeic acid