Determination of SOD-like activity of copper(II) complexes with alpha-amino acid dithiocarbamates

The SOD-like activity of the copper(II) complexes of five amino acid (Gly, Ala, Ser, Asn, Gly) dithiocarbamates was determined. The concentration of the complexes that inhibit by 50% (IC50) the reduction of nitroblue tetrazolium by superoxide radical (generated by xanthine oxidase) lies between 1.2 mu M (Glu) and 20 mu M (Gly). Quantitative structure-activity relationships, QSAR, were established between pIC(50) (-log IC50) and the molar refraction values of the amino acid substituents, as well as Cu(I)/Cu(II) oxidation potentials (determined by cyclic voltammetry). The high SOD-like activity of the Glu dithiocarbamate complex is interrupted to be due to its distorted geometry based on EPR spectra and conductimetric titration data. (C) 1997 Elsevier Science Inc.