Superoxide Dismutase Mimetic Activities of Metal Complexes of L-2(2-Pyridyl)-1-pyrroline-5-carboxylic Acid (Pyrimine)

We previously isolated the strain Z-54 (Serratia marcescens O5:H1) which produces a reddish-violet pigment. The structure of this pigment was confirmed to be that of a peptide complex containing Fe2+ and L-2(2-pyridyl)-1-pyrroline-5-carboxylic acid (pyrimine), as a chromophore. We measured the superoxide dismutase mimetic activities for the pyrimine-metal complexes by xanthine oxidase/nitroblue tetrazolium and cytochrome c methods and found that the pyrimine-Cu2+ (2:1) complex shows the highest activity yet reported (IC50 = 0.11 μM) among the complexes tested. Pyrimine-Cu+, -Fe2+ and -Mn2+ complexes also gave relatively high SOD mimetic activities. ESR spectra observed for pyrimine-Cu2+ (4:1) showed the structure of the Cu2+-complex to be tetrahedral and coordinated with four nitrogen atoms. These results support the idea that the pyrimine-metal complexes might be potent SOD mimics.