Some organic selenium-containing compounds such as ebselen [2-phenyl-1,2-benzisoselenazol -3(2H)-one] react very fast with peroxynitrite stoichiometrically and preempt the formation of oxidizing species from peroxynitrite. 14 Recently, several iron and manganese porphyrin complexes were reported to decompose ONOO - at a rate up to 2.2 × 10 6 M - 1 s - 1 . 15a - d In particular, the iron porphyrin complexes are efficient catalysts for the decomposition of peroxynitrite, 15d ...