Degradation of γ- and α-tocopherol and formation of 5-nitro-γ-tocopherol induced by peroxynitrite in liposomes and skeletal muscle

Peroxynitrite, formed from the reaction between nitric oxide and superoxide, can participate in free radical-mediated reactions with cellular components in muscle to (1) initiate lipid oxidation via the production of lipid hydroperoxides, and (2) produce novel nitrated products. 5-Nitro-γ-tocopherol (NGT) is formed by the electrophilic substitution reaction between peroxynitrite and γ-tocopherol. The objective of this research was to examine the utility of NGT as a lipid-phase, peroxynitrite-specific biomarker in muscle foods. NGT was detected when exogenous peroxynitrite was added to liposomes containing γ-tocopherol and homogenates from chicken dark and turkey light muscle with added γ-tocopherol. Detectable levels of NGT were not observed in either minced turkey light muscle stored at −20 °C or chicken dark muscle stored at 4 °C. These results suggest that NGT is not a suitable biomarker to confirm the presence of endogenously produced peroxynitrite in muscle foods.