A reevaluation of the peroxynitrite scavenging activity of some dietary phenolics.
Peroxynitrite is implicated in many diseases. Hence, there is considerable interest in potential therapeutic peroxynitrite scavengers. Diet-derived phenolics have been claimed to be powerful peroxynitrite scavengers. However, the reactivity of peroxynitrite can be significantly modified by bicarbonate and this has not been considered in evaluations of the scavenging activity of phenols. Bicarbonate (25 mM) significantly decreased the ability of several phenolic compounds (caffeic acid, o- and p-coumaric acid, gallic acid, ferulic acid) but not others (catechin and epicatechin) to inhibit peroxynitrite-mediated tyrosine nitration. Bicarbonate (25 mM) also decreased the ability of catechin, epicatechin, quercetin and ferulic acid but not chlorogenic acid, gallic acid, caffeic acid and o-coumaric acid to inhibit peroxynitrite-mediated alpha(1)-antiproteinase inactivation. These results show that physiological concentrations of bicarbonate substantially modify the ability of dietary phenolics to prevent peroxynitrite-mediated reactions. When assessing compounds for peroxynitrite scavenging, experiments should be conducted in the presence of bicarbonate to avoid misleading results.
Ketsawatsakul
U
U
International Antioxidant Research Centre, GKT School of Biomedical Sciences, Third Floor Hodgkin Building, St. Thomas Street, London, SE1 9RT, United Kingdom.
Whiteman
M
M
Halliwell
B
B
D001639:Bicarbonates / Q000737:chemistry; D002109:Caffeic Acids / Q000737:chemistry; D002726:Chlorogenic Acid / Q000737:chemistry; D003373:Coumaric Acids / Q000737:chemistry; D004032:Diet; D016166:Free Radical Scavengers / Q000737:chemistry*; D005707:Gallic Acid / Q000737:chemistry; D007700:Kinetics; D009566:Nitrates / Q000737:chemistry* / Q000494:pharmacology; D016877:Oxidants / Q000737:chemistry* / Q000494:pharmacology; D010196:Pancreatic Elastase / Q000037:antagonists & inhibitors; D010636:Phenols / Q000737:chemistry*; D013329:Structure-Activity Relationship; D014443:Tyrosine / Q000737:chemistry*; D000515:alpha 1-Antitrypsin / Q000378:metabolism
D001639:Bicarbonates; D002109:Caffeic Acids; D003373:Coumaric Acids; D016166:Free Radical Scavengers; D009566:Nitrates; D016877:Oxidants; D010636:Phenols; D000515:alpha 1-Antitrypsin; C039642:peroxynitric acid; D002726:Chlorogenic Acid; D014443:Tyrosine; D005707:Gallic Acid; C004999:ferulic acid; D010196:Pancreatic Elastase; C040048:caffeic acid