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

Abstract

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 (1)H, (13)C{(1)H}, and (77)Se{(1)H} NMR spectroscopy, mass spectrometry, and X-ray crystallography. Upon H2O2 treatment, selone and thione binding to Cu(+) prevents oxidation to Cu(2+); instead, the chalcogenone ligand is oxidized. Thus, copper coordination by sulfur and selenium compounds can provide targeted sacrificial antioxidant activity.

Diverse silver(i) coordination chemistry with cyclic selenourea ligands

“…Coinage metal complexes of selenium-bearing ligands have a number of current applications, including usage as emissive materials, 21 or studying the antioxidant properties of selenium. [22][23][24] Copper 25 and gold 18 coordination chemistry of selenoureas has been explored quite extensively, but there are notably few studies on silver, 26 and no silver complexes of aryl-substituted selenoureas have been previously reported. Silver coordination complexes show promise in a number of applications, including as antimicrobial therapeutics, 27 catalysts 28,29 or co-catalysts 30 for a number of organic transformations, and precursors to silver chalcogenide materials.…”

Characterization and Structural Insights of the Reaction Products by Direct Leaching of the Noble Metals Au, Pd and Cu with N,N′-Dimethyl-piperazine-2,3-dithione/I2 Mixtures

“…Copper(I) complexes with thione donors are not uncommon and those coordinated to biologically relevant ligands such as N , N ′-dimethylimidazole-thione or others, are of interest to elucidate how coordination to sulfur and selenium inhibits copper-mediated oxidative damage. It has been shown that, when bound to Cu + , thione (and selone) ligands protect Cu + from oxidation [ 30 , 31 ].…”

Role of Hydrogen Bonding by Thiones in Protecting Biomolecules from Copper(I)-Mediated Oxidative Damage

“…Recently, Brumaghim and co-workers have demonstrated, in their pioneer work, that the N,N′-disubstituted imidazolebased thione/selone can prevent the Cu(I)-mediated oxidative damage of biomolecules by directly binding to the redox active Cu(I) center and thereby not allowing H 2 O 2 to interact with the metal ion. 18 For instance, Im Me S Me and its selenium analogue (Im Me Se Me ) were reported to show their antioxidant activities by coordinating to the Cu(I) center of tris(3,5dimethylpyrazolyl)-methane (Tpm) Cu(I) complex, [TpmCu-(CH 3 CN)] + (11), through the lone pair of S and Se atoms, which led to the formation of the corresponding redox inactive [TpmCu(thione)] + and [TpmCu(selone)] + complexes. 18,19 Interestingly, because of the presence of a lone pair at the S or Se center of Cu(I)-bound thione or selone of [TpmCu-(thione)] + or [TpmCu(selone)] + , the approaching H 2 O 2 may readily interact with the metal-bound thione or selone, instead of the Cu(I) ion which is buried inside the complex (Figure 2).…”