Mechanism of inhibition of peroxynitrite-induced oxidation and nitration by [6]-gingerol

[6]-Gingerol potently inhibits peroxynitrite-induced oxidation and nitration reactions, but its mechanism of action is unclear. In order to discover the mechanism of inhibition, [6]-gingerol was reacted with peroxynitrite and the reaction mixture was analyzed using HPLC. The HPLC chromatogram showed one novel peak, indicative of the formation of a reaction product between [6]-gingerol and peroxynitrite. This compound was purified and identified as a symmetrical dimer of [6]-gingerol covalently linked at the aromatic ring. It has been assumed that this dimer is generated from a phenoxyl radical intermediate produced from [6]-gingerol via one-electron oxidation by peroxynitrite-derived radicals. We propose a mechanism in which [6]-gingerol scavenges peroxynitrite-derived radicals and consequently inhibits peroxynitrite-incluced oxidation and nitration reactions.