6-Methylnitroarachidonate: A novel esterified nitroalkene that potently inhibits platelet aggregation and exerts cGMP-mediated vascular relaxation

Abstract

Nitro-fatty acids represent endogenously occurring products of oxidant-induced nitration reactions. We have previously synthesized a mixture of four isomers of nitroarachidonic acid, a novel anti-inflammatory signaling mediator. In this study, we synthesized and chemically and biologically characterized for the first time an esterified nitroalkene derived from the nitration of methylarachidonate (AAMet): 6-methylnitroarachidonate (6-AAMetNO2). Synthesis was performed by reacting AAMet with sodium nitrite under acidic conditions. Analysis by mass spectrometry (positive-ion ESI-MS) showed an [M+H]+ ion of m/z 364, characteristic of AAMetNO2. Fragmentation of this ion yielded a daughter ion at m/z 317, corresponding to the neutral loss of the nitro group ([M+H−HNO2]+). Furthermore, IR signal at 1378cm−1 and NMR data confirmed the structure of a 6-nitro-positional isomer. This novel esterified nitroalkene was capable of promoting vascular protective actions including: (a) the induction of vasorelaxation via endothelium-independent mechanisms, associated with an increase in smooth muscle cell cGMP levels, and (b) a potent dose-dependent inhibition of human platelet aggregation. We postulate that 6-AAMetNO2 could be a potential drug for the prevention of vascular and inflammatory diseases, and the presence of the methyl group may increase its pharmacological potential.