Definition: Porphyrins which are combined with a metal ion. The metal is bound equally to all four nitrogen atoms of the pyrrole rings. They possess characteristic absorption spectra which can be utilized for identification or quantitative estimation of porphyrins and porphyrin-bound compounds.
pigments (porphyrins) "combined with a metal ion"; iron porphyrins
manganese(III)-tetrakis(4-benzoic acid)porphyrin [ Mn(III) tetrakis(4-benzoic acid)porphyrin,MnTBAP,manganese(III) beta-octabromo-meso-tetrakis(4-carboxyphenyl)porphyrin ] protects against paraquat-induced endothelial cell injury; structure given in first source
