Identification of 3-nitro-L-tyrosine, a product of nitric oxide and superoxide, as an indicator of oxidative stress in the human brain.

3-Nitro-L-tyrosine synthesized from L-tyrosine by peroxynitrite, a product of superoxide and nitric oxide, was identified for the first time in human brains. By quantitative analysis using high-performance liquid chromatography with multi-electrochemical detectors, 3-nitro-L-tyrosine concentration in the gray matter was higher in the cerebrum than in the cerebellum; 0.96 and 0.29 nmol/g wet weight, respectively. On the other hand, L-tyrosine concentration was not different. 3-Nitro-L-tyrosine in the brain may be used as an indicator of oxidative stress induced by reactive oxygen species and nitric oxide.