posted on 2022-01-14, 12:35authored byRóbert Diószegi, Dóra Bonczidai-Kelemen, Attila Cs. Bényei, Nóra V. May, István Fábián, Norbert Lihi
Copper(II)
complexes of pyridine-based ligands functionalized with
alanine (PydiAla) and tyrosine (PydiTyr)
moieties have been synthesized as novel superoxide dismutase mimics.
The complexes were characterized by pH-potentiometric, spectroscopic
(UV–vis, circular dichroism, mass spectrometry, electron paramagnetic
resonance spectroscopy), computational (DFT), and X-ray diffraction
methods. Both ligands form high stability copper(II) complexes via
the (Npy,N–,N–) donor
set supported by the binding of the carboxylate pendant arms. Although
the coordination mode is the same for the two systems, the tyrosine
containing counterpart exhibits increased copper(II) binding affinity,
which is most likely due to the presence of the aromatic moiety of
the side chains. Both copper(II) complexes are capable of binding N-methylimidazole, and the formation of the corresponding
ternary species was observed at physiological pH. The binary and ternary
copper(II) complexes exhibit high SOD activity. The PydiTyr complex exhibits about 1 order of magnitude higher activity than
the PydiAla complex. This is probably due to the presence
of the phenolic OH group in the former species, which promotes the
binding of the superoxide anion radical to the metal center. The results
serve as a basis for designing highly efficient copper(II) mimics
for medical and practical applications.