- Synthesis and antioxidant activity of O-alkyl selenocarbamates, selenoureas and selenohydantoins
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The preparation of three different families of lipophilic organoselenium compounds (aryl- and sugarderived selenoureas, O-alkyl selenocarbamates and selenohydantoins) has been carried out in order to evaluate their in vitro antioxidant profile, analyzing the influence of the selenium-containing functional group, and the substituents on the activity. Title compounds have therefore been studied for the first time as free radical, hydrogen peroxide, alkyl peroxides and nitric oxide scavengers using colorimetric methods; furthermore, their glutathione peroxidase-like activity has also been analyzed by NMR spectroscopy. Free radical scavenging activity has been evaluated using the DPPH method; the strongest free radical scavengers were found to be both, aryl- and sugar-derived selenoureas, with EC50 values ranging 19-46 lM. Concerning anti-H2O2 activity, measured by the horseradish peroxidase-mediated oxidation of phenol red, the best results were achieved for aryl selenohydantoins, showing a 61-76% inhibition at 0.5 mM concentration. Organoselenium compounds were also found to be capable of inhibiting the chain reaction involving lipid peroxidation (ferric thiocyanate method); thus, when tested at 0.74 mM, sugar selenocarbamates exhibited 49-71% inhibition of alkyl peroxides-mediated degradation of linoleic acid. Nitric oxide scavenging was studied by transforming sodium nitroprusside into nitrite ion, which in turn was transformed into an easily UV-detectable azocompound; aryl selenocarbamates exhibited 64-80% inhibition at 0.71 mM concentration. It has also been demonstrated that selenoxo compounds can behave as excellent glutathione peroxidase mimics; thus a 0.05 molar equiv. of the title compounds catalyzed efficiently the H2O2-mediated oxidation of dithiothreitol into the corresponding cyclic disulfide, mimicking removal of H 2O2 exerted by glutathione peroxidase; t1/2 values were found to be quite low for aryl- and sugar-derived selenoureas (2.0-12.7 min).
- Merino-Montiel, Penelope,Maza, Susana,Martos, Sergio,Lopez, Oscar,Maya, Ines,Fernandez-Bolanos, Jose G.
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p. 582 - 592
(2013/05/22)
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- Isoselenocyanates derived from amino acid esters: An expedient synthesis and application to the assembly of selenoureidopeptidomimetics, unsymmetrical Selenoureas and selenohydantoins
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An important class of organoselenium compounds-α-isoselenocyanato esters 4 hasbeen prepared by a reaction of α-isocyano esters with elemental selenium powder. The reaction issimple, rapid and all the isoselenocyanates havebeen isolated as stable ones after chromatographic purification. These hitherto unreported classes of molecules would be useful building blocks for the preparation of variety of selenium containing peptidomimetics. In this study, the utility of the title molecules in the preparation of selenoureidopeptidomimetics 6, unsymmetrical selenoureas 8 and selenohydantoins 10 isdemonstrated.
- Hemantha, Hosahalli P.,Sureshbabu, Vommina V.
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p. 644 - 651
(2011/09/14)
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