The catecholic antioxidant piceatannol is an effective nitrosation inhibitor via an unusual double bond nitration.
Piceatannol (1) was found to be more effective than caffeic acid, an established antinitrosating agent, in inhibiting N-nitrosation of 2,3-diaminonaphthalene. Product analysis of the reaction mixture of 1 (20 microM) with nitrite ions (80 microM) at pH 3.0 and at 37 degrees C showed conversion to a single major nitration product, (E)-3,3',4,5'-tetrahydroxy-beta-nitrostilbene (2) (68% yield). This would result from an unexpected nitration at the double bond sector via the 4-phenoxyl radical, which was analyzed at the unrestricted DFT level.
De Lucia
Maria
M
Department of Organic Chemistry and Biochemistry, University of Naples Federico II, Via Cintia, I-80126 Naples, Italy.
Panzella
Lucia
L
Crescenzi
Orlando
O
Napolitano
Alessandra
A
Barone
Vincenzo
V
d'Ischia
Marco
M
D000975:Antioxidants / Q000494:pharmacology*; D002109:Caffeic Acids / Q000494:pharmacology; D002396:Catechols / Q000494:pharmacology*; D007477:Ions; D008968:Molecular Conformation; D009281:Naphthalenes / Q000037:antagonists & inhibitors / Q000378:metabolism; D009566:Nitrates / Q000737:chemistry / Q000378:metabolism; D009573:Nitrites / Q000737:chemistry / Q000378:metabolism; D015538:Nitrosation / Q000187:drug effects*; D010636:Phenols / Q000032:analysis / Q000737:chemistry / Q000378:metabolism; D010938:Plant Oils / Q000737:chemistry; D013267:Stilbenes / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*
D000975:Antioxidants; D002109:Caffeic Acids; D002396:Catechols; D007477:Ions; D009281:Naphthalenes; D009566:Nitrates; D009573:Nitrites; D010636:Phenols; D010938:Plant Oils; D013267:Stilbenes; C042329:phenoxy radical; C041525:3,3',4,5'-tetrahydroxystilbene; C040048:caffeic acid