Function of Thioredoxin Reductase as a Peroxynitrite Reductase Using Selenocystine or Ebselen
摘要:
The activity of mammalian thioredoxin reductase as a peroxynitrite reductase was investigated. Peroxynitrite was infused to maintain a 0.2 mu M steady-state concentration in potassium phosphate buffer (pH 7.4). Benzoate hydroxylation and nitrite formation were used as indices of oxidation reactions of peroxynitrite and of peroxynitrite reduction, respectively. In the presence of NADPH (10 mu M), thioredoxin reductase at 50 nM alone did not significantly scavenge peroxynitrite, as shown by there being no significant effect on benzoate hydroxylation or nitrite formation. However, when selenocystine (1 mu M) or ebselen (2 mu M) was present in the reaction mixture, there was significant suppression of benzoate hydroxylation and an increase in nitrite formation until all the NADPH was oxidized. The addition of thioredoxin did not enhance these effects. In contrast, peroxynitrite reduction by ebselen complexed with BSA was enhanced by the presence of thioredoxin. efficiently reduced ebselen selenoxide back to In parallel experiments, thioredoxin reductase ebselen.
photochemical reaction of 2-aryl-1,2-benzisoselenazol-3(2H)-ones (1) in benzene was found to give dibenzo[b,f][1,4]selenazepin-11(10H)-ones (2). On the other hand, the photochemical reaction of 1 in t-butyl alcohol afforded 2-(2-hydroxy-2-methylpropylseleno)benzanilide, 2-(methylseleno)benzanilide, and 2-aryl-1,2-benzisoselenazol-3(2H)-one 1-oxides together with the photoisomer 2. Mechanisms for these
H)-one, rapidly reacts with peroxynitrite, the rate constant being of the order of 10(6) M-1 s-1; the reaction yields the selenoxide of the parent molecule, 2-phenyl-1,2-benzisoselenazol-3(2H)-one 1-oxide, as the sole selenium-containing product; a stoichiometry of 1 mol of ebselen reacted and of the selenoxide formed per mole of peroxynitrite was observed. The reaction was studied in detail at neutral
Chemistry Related to the Catalytic Cycle of the Antioxidant Ebselen
作者:Kai N. Sands、Austin L. Burman、Esther Ansah-Asamoah、Thomas G. Back
DOI:10.3390/molecules28093732
日期:——
formation of benzaldehyde. Oxidation of ebselen seleninic acid did not afford a selenonium seleninate salt as previously observed with benzene seleninic acid, but instead generated a mixture of the seleninic and selenonic acids. Thiolysis of ebselen with benzyl thiol was faster than oxidation by ca. an order of magnitude and produced a stable selenenyl sulfide. When glutathione was employed, the product
抗氧化药物依布硒啉已在实验室和临床试验中得到广泛研究。它通过与谷胱甘肽或其他硫醇还原来破坏过氧化氢的催化机制很复杂,并且一直是争论不休的主题。在对几个关键步骤的重新研究过程中,我们发现构成依布硒啉第一个氧化产物的亚硒酰胺经历了容易的可逆甲醇分解,生成不稳定的亚硒酸酯和两种二聚产物。在与苯甲醇的反应中,亚硒酰胺产生了一种苯甲酯,该苯甲酯很容易通过硒氧化物消除反应,并形成苯甲醛。依布硒酸的氧化并没有像之前用苯硒酸观察到的那样得到硒酸盐,而是产生了硒酸和硒酸的混合物。依布硒啉与苄基硫醇的硫解比 ca 的氧化快。一个数量级并产生稳定的硒基硫化物。当使用谷胱甘肽时,产物迅速歧化为谷胱甘肽二硫化物和依布硒化物。S-苄基硒基硫化物的氧化,或亚硒酰胺与苄基硫醇的硫解作用,提供了一种瞬时硫醇亚硒酸盐,它也很容易经历硒氧化物消除。当同时存在硫醇和三乙胺催化时,S-苄基衍生物很容易歧化。当暴露于环境光或紫外线 (360
Mlochowski, Jacek; Kloc, Krystian; Syper, Ludwik, Liebigs Annalen der Chemie, 1993, # 12, p. 1239 - 1244
作者:Mlochowski, Jacek、Kloc, Krystian、Syper, Ludwik、Inglot, Anna D.、Piasecki, Egbert
DOI:——
日期:——
Fisher, Hartmut; Dereu, Norbert, Bulletin des Societes Chimiques Belges, 1987, vol. 96, # 10, p. 757 - 768