The complexes were also studied under the same conditions for a direct comparison of the results. All complexes show one-electron redox wave in the plotted potential range, attributed to the Cu(II)/Cu(I) redox couple. Second pair of peaks was

only observed in the case of 1c compound. For four of them (1a, 1b, 2b and 3b) only single reduction waves were present additionally. The E 1/2 values are within the range of −0.538 V (1b) to 0.076 V (2c). A considerable dispersion of E values was observed. It is possible to observe that E values are increasing in the following row: a < b < c for ligands and 2 series of complexes. However, for 3 series of complexes there is an inverse relationship: c < b < a. In case of complexes with 1a ligand (2a and 3a), one observes peak separation of roughly 45 mV, in contrast to complexes with ligands 1b and 1c which exhibit three times greater peak separation YH25448 molecular weight (130–190 mV). The peak-to-peak separation (ΔE p) and proportion of the anodic peak current and the cathodic peak current mostly indicates a quasireversible process. However, in the case of 1a, 2a and 3a compounds, there is a reversible process. Table 2 Cyclic voltammetry data (V) No of compounds E pa 1 E pc 1 E 1/2 1 E pa 2 E pc 2 E 1/2 2 1a 0.081 −0.344 −0.131 – – – 1b −0.400 −0.675 −0.538 −0.287a – – 1c 0.097 −0.014 0.042 −0.034 −0.380 −0.207 2a −0.216 −0.264 −0.250 – – – 2b −0.219 −0.349 −0.284

0.043a – – 2c 0.158 −0.005 0.076 – – – 3a 0.123 Eltanexor order −0.082 0.021 – – – 3b −0.148 −0.339 −0.244 0.225a – – 3c −0.229 −0.400 −0.315 – – – aOnly anodic peak It is known that an adequate Cu(II)/Cu(I) redox potential for effective

catalysis of superoxide radical must be required between −0.405 V for O2/O 2 •− and +0.645 V for O 2 •− /H2O2 selleck chemicals versus SCE (at pH 7) or between −0.762 and +0.29 V versus Ag/AgNO3/ACN, respectively. The Cu(II)/Cu(I) redox couples of both series of complexes (2a–c, 3a–c) are within this Oxymatrine potential range; therefore, these complexes are expected to exhibit SOD-like activity. The highest enhancement of SOD activity exhibits complexes with ligand 1c (2c, 3c). To make a Cu(II) complex thermodynamically competent in the H2O2 detoxification, the redox potential of the metal-centred redox couples should fall within the 0.04 V (O2/H2O2) to 1.01 V (H2O/H2O2) versus SCE potential range or between −0.32 and 0.65 V versus Ag/AgNO3 electrode. All the complexes (2a–c, 3a–c) have suitable E 1/2 potential and showed activity for the catalytic decomposition of H2O2. Among them 2a, 2b, 3b and 3c complexes are comparably effective as CAT mimics. Conclusions In this study, electrochemical and antioxidant properties of six Cu(II) mononuclear complexes with pyrazole-based ligands were evaluated. The majority of Cu(II) complexes, under the experimental conditions used in this study, were found to be trifunctional enzyme mimics possessing SOD, CAT and GPx-like catalytic activities.