Peroxynitrite anion scavenging activity was measured by monitoring the oxidation of
DHR-123 to the fluorescent product rhodamine at excitation and
emission wavelengths of 500 and 536 nm, respectively. A working
solution of 50 lM of DHR-123 diluted from the stock solution
(28 mM DHR-123 in DMSO) was placed on ice in the dark immediately
before the assay.