ABSTRACT
A series of guanidines and their copper (II) complexes were investigated for their radical scavenging activity including peroxyl radicals (ROO), superoxide anion (O2), hydroxyl ('OH), and reactive hydrogen per- oxide (H202) species. Among the Cu(II) complexes, Cu-MR-9-2 shows the highest, Cu-MR-9-3, Cu-MR-9-6 less and Cu-MR-9-1 least antioxidant potential. The Cu(II) complexes show better Fea'-chelating activity than that of ligands. Among the Cu(II) complexes Cu-MR-9-2 was found to have the highest, Cu-MR-9-6 moderate, MR-9-3 less and Cu-MR-9-1 least ferric reducing capacity. The IC50 values for ligands (MR-9-1, MR-9-2, MR- 9-3, MR-9-6) were determined to be 197.53 ± 7.13, 189.07 ± 7.34, 207.98 ± 6.78 and 233.38 ±6.37 pM, which showed lower antioxidant activity than their Cu(II) complexes. The IC,o values for ascorbic acid were found to be 51.60 ± 13.18 pM. The Cu(I) metal compounds (Cu-MR-9-1,Cu-MR-9-2, Cu-MR-9-3 and Cu-MR-9-6) were detected to be the most powerful scavengers of the hydroxyl radical with IC50 up to 108.03 ± 11.34 pM, 101.41 ±12.10 pM, 90.59 ± 11.53 pM and 88.86 ± 13.16 pM, respectively.
