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Enzymatic nitration of phytophenolics: evidence for peroxynitrite‐independent nitration of plant secondary metabolites
Author(s) -
Sakihama Yasuko,
Tamaki Ryoko,
Shimoji Hisashi,
Ichiba Toshio,
Fukushi Yukiharu,
Tahara Satoshi,
Yamasaki Hideo
Publication year - 2003
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(03)01059-7
Subject(s) - peroxynitrite , chemistry , nitration , reactive nitrogen species , horseradish peroxidase , peroxidase , antioxidant , biochemistry , enzyme , guaiacol , organic chemistry , superoxide
Peroxynitrite (ONOO − ), a reactive nitrogen species, is capable of nitrating tyrosine residue of proteins. Here we show in vitro evidence that plant phenolic compounds can also be nitrated by an ONOO − ‐independent mechanism. In the presence of NaNO 2 , H 2 O 2 , and horseradish peroxidase (HRP), monophenolic p ‐coumaric acid ( p ‐CA, 4‐hydroxycinnamic acid) was nitrated to form 4‐hydroxy‐3‐nitrocinnamic acid. The reaction was completely inhibited by KCN, an inhibitor for HRP. The antioxidant ascorbate suppressed p ‐CA nitration and its suppression time depended strongly on ascorbate concentration. We conclude that nitrogen dioxide radical (NO 2 • ), but not ONOO − , produced by a guaiacol peroxidase is the intermediate for phytophenolic nitration.