Peroxynitrite and NO+ donors form colored nitrite adducts with sinapinic acid: potential applications.
Sinapinic acid (3,5-dimethoxy-4-hydroxycinnamic acid, SA) reacted with peroxynitrous acid at neutral pH with a second-order rate constant of 812 M(-1)s(-1), to yield a red product (lambda(max), 532 nm). The identical colored product could be formed with acidified decomposed peroxynitrous acid solutions or nitrite at slower rates (0.1M HCl, 8.32 M(-1)s(-1); 10% acetic acid, 0.0004 M(-1)s(-1)). The red compound is thought to be O-nitrososinapinic acid (3,5-dimethoxy-4-nitrosooxycinnamic acid) which can be formed by reaction with either peroxynitrous acid or nitrous acid. The extinction coefficient of O-nitrososinapinic acid (ONSA) was estimated to be 8419 M(-1)cm(-1) at 510 nm in 10% acetic acid and 90% acetonitrile. ONSA was also formed via NO(+) transfer from S-nitrosoglutathione (GSNO). ONSA in turn can S-nitrosate low molecular weight thiols and protein thiols. SA was also shown to act as a peroxynitrite sink as it effectively prevented the oxidation of dihydrorhodamine under physiological conditions. The fact that O-nitrososinapinic acid is stable and can be used to S-nitrosate thiol containing amino acids, peptides, and proteins makes it a potentially useful reagent in the study of S-nitrosothiol biochemistry and physiology. In addition, the relatively high extinction coefficient of O-nitrososinapinic acid means that it could be utilized as an analyte for the spectroscopic detection of peroxynitrite or NO(+)-donors in the submicromolar range.
Akhter
Shirin
S
Department of Chemistry and Biochemistry, University of Windsor, 401 Sunset Avenue, Windsor, Ont., Canada N9B 3P4.
Green
James R
JR
Root
Paul
P
Thatcher
Gregory J
GJ
Mutus
Bulent
B
D003373:Coumaric Acids / Q000138:chemical synthesis / Q000737:chemistry*; D007700:Kinetics; D008981:Molsidomine / Q000031:analogs & derivatives* / Q000737:chemistry; D020030:Nitric Oxide Donors / Q000737:chemistry*; D009573:Nitrites / Q000737:chemistry; D009608:Nitrous Acid / Q000737:chemistry; D030421:Peroxynitrous Acid / Q000138:chemical synthesis / Q000737:chemistry*; D012235:Rhodamines / Q000737:chemistry; D026422:S-Nitrosoglutathione / Q000737:chemistry
D003373:Coumaric Acids; D020030:Nitric Oxide Donors; D009573:Nitrites; D012235:Rhodamines; C098097:dihydrorhodamine 6G; D030421:Peroxynitrous Acid; D026422:S-Nitrosoglutathione; C002385:linsidomine; C073734:sinapinic acid; D008981:Molsidomine; D009608:Nitrous Acid