Oxidation of Biologically Relevant Chalcogenones and Their Cu(I) Complexes: Insight into Selenium and Sulfur Antioxidant Activity

Hydroxyl radical damage to DNA causes
disease, and sulfur and selenium antioxidant coordination to hydroxyl-radical-generating
Cu+ is one mechanism for their observed DNA damage prevention.
To determine how copper binding results in antioxidant activity, biologically
relevant selone and thione ligands and Cu+ complexes of
the formula [Tpm*Cu­(L)]+ [Tpm* = tris­(3,5-dimethylpyrazolyl)­methane;
L = N,N′-dimethylimidazole
selone or thione] were treated with H2O2 and
the products analyzed by 1H, 13C­{1H}, and 77Se­{1H} NMR spectroscopy, mass spectrometry,
and X-ray crystallography. Upon H2O2 treatment,
selone and thione binding to Cu+ prevents oxidation to
Cu2+; instead, the chalcogenone ligand is oxidized. Thus,
copper coordination by sulfur and selenium compounds can provide targeted
sacrificial antioxidant activity.