Novel N-methylated ebselenamine antioxidants were prepared from their corresponding diselenides with iodomethane. All ebselenamines showed excellent chain-breaking and glutathione peroxidase (GPx)-like activities. These could also inhibit the lipid peroxidation much...

Selenazolonamines 10 a-d with free amine (-NH 2 ) group, a new series of preventive and radical-trapping antioxidants were synthesized from their corresponding diselenides. The radical-trapping antioxidant capacity of compounds 10 a-d was determined in a chlorobenzene/ water membrane-like model system in which azo-initiated peroxidation of linoleic acid was carried out in the lipid phase. The regeneration occurred in the aqueous ascorbic acid as co-antioxidant, which could regenerate the antioxidants and enhance their inhibition times. The best antioxidant 10 d substituted with para-NMe 2 a strong electron-donating group quenched the peroxyl radicals more efficiently than α-tocopherol almost 5.5-fold longer inhibition time. The novel selenazolonamines 10 a-d and their derivatives exhibited good preventive i. e. glutathione peroxidaselike activity in the coupled reductase assay. Based on 77 Se NMR spectroscopy, a catalytic cycle for 10 d, involving diselenide, selenosulfide, and selenol as intermediates was proposed. The mechanism for quenching of peroxyl radicals for 10 d was also considered to be involved via protoncoupled electron transfer reaction.

Bis(3-amino-1-hydroxybenzyl)diselenide containing two ortho groups was synthesized from 7-nitro-3H-2,1-benzoxaselenole and in situ generated sodium benzene tellurolate (PhTeNa). One-pot synthesis of 1,3-benzoselenazoles was achieved from bis(3-amino-1-hydroxybenzyl)diselenide and aryl aldehydes using acetic acid as a catalyst. The X-ray crystal structure of chloro-substituted benzoselenazole revealed a planar structure with T-shaped geometry around the Se atom. Both natural bond orbital and atoms in molecules calculations confirmed the presence of secondary Se···H interactions in bis(3-amino-1-hydroxybenzyl)diselenide and Se···O interactions in benzoselenazoles, respectively. The glutathione peroxidase (GPx)-like antioxidant activities of all compounds were evaluated using a thiophenol assay. Bis(3-amino-1-hydroxybenzyl)diselenide and benzoselenazoles showed better GPx-like activity compared to that of the diphenyl diselenide and ebselen, used as references, respectively. Based on 77Se{1H} NMR spectroscopy, a catalytic cycle for bis(3-amino-1-hydroxybenzyl)diselenide using thiophenol and hydrogen peroxide was proposed involving selenol, selenosulfide, and selenenic acid as intermediates. The potency of all GPx mimics was confirmed by their in vitro antibacterial properties against the biofilm formation of Bacillus subtilis and Pseudomonas aeruginosa. Additionally, molecular docking studies were used to evaluate the in silico interactions between the active sites of the TsaA and LasR-based proteins found in Bacillus subtilis and Pseudomonas aeruginosa.

Copper-catalyzed direct selenation of substituted 2-bromo-N-phenylbenzamide substrates with elemental selenium powder provided a series of methoxysubstituted isoselenazolones via the C−Se and Se−N bond formations. Phenolic substituted isoselenazolones have been obtained by O-demethylation of the corresponding methoxy-substituted analogues using boron tribromide. Some isoselenazolones have been structurally characterized by X-ray single-crystal analysis. The glutathione peroxidase (GPx)-like antioxidant activity of isoselenazolones has been evaluated both in thiophenol and coupled-reductase assays. All isoselenazolones showed good GPx-like activities in the coupled-reductase assay. The ferric-reducing antioxidant power of phenolic antioxidants has also been evaluated. The best phenolic antioxidants were found to be good ferric-reducing antioxidant power agents. The single electron transfer, hydrogen atom transfer, and proton-coupled electron transfer mechanisms for the antioxidant properties of all catalysts have been supported by density functional theory calculations. The catalytic cycle was proposed for one of the phenolic isoselenazolones involving diselenide, selenenyl sulfide, selenol, and selenenic acid as intermediates using 77 Se{ 1 H} NMR spectroscopy.