- Spirodiazaselenuranes: Synthesis, structure and antioxidant activity
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In this paper, the synthesis, characterization and glutathione peroxidase and peroxynitrite scavenging activities of a series of stable spirodiazaselenuranes are described. The spiro compounds were synthesized in good yields by oxidative cyclization of diaryl selenides bearing amide moieties. All the selenides and spiro derivatives were characterized by 1H, 13C and 77Se NMR spectroscopy, mass spectral techniques and the structures of some of the spirodiazaselenuranes were confirmed by single crystal X-ray crystallography. The structures reveal that the selenium atom occupies the center of a distorted trigonal bipyramid core with two nitrogen atoms occupying the apical positions and two carbon atoms and the selenium lone pair occupying the equatorial positions. Mechanistic investigations indicate that the spirocyclization occurs via the formation of selenoxide intermediates. The new compounds were evaluated for their glutathione peroxidase (GPx) mimetic activity by using H2O2 as a substrate and glutathione (GSH) as a co-substrate. It was found that the substituents attached to the nitrogen atom of the selenazole ring have a significant effect on the GPx activity. While the introduction of electron withdrawing groups such as -Cl, -Br etc. to the phenyl ring decreases the activity, the introduction of electron donating groups such as -OH, -OMe significantly enhances the GPx activity of both diaryl selenides and spirodiazaselenuranes. In addition to GPx activity, the selenides and spiro derivatives were studied for their ability to inhibit peroxynitrite (PN)-mediated nitration of bovine serum albumin (BSA) and oxidation of dihydrorhodamine 123. These studies indicate that the diarylselenides effectively inhibit the PN-mediated nitration and oxidation reactions by reacting with PN to produce the corresponding spirodiazaselenuranes.
- Lamani, Devappa S.,Bhowmick, Debasish,Mugesh, Govindasamy
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p. 7933 - 7943
(2013/07/05)
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- Inhibition of Peroxynitrite-Mediated Reactions by Vanillin
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Several neurodegenerative diseases such as Alzeimer's and Parkinson's as well as septic shock and inflammation involve formation of reactive oxygen and nitrogen species that include peroxynitrite (PON). PON can also react with endogenous antioxidants. Therefore, dietary supplementation with antioxidants may help in these diseases. An exogenous antioxidant, vanillin (4-hydroxy-3-methoxy-benzaldehyde), used widely as a food flavoring agent, was evaluated for its ability to scavenge PON and inhibit PON-mediated reactions. Nitration of tyrosine by PON was assessed by high-performance liquid chromatography (HPLC). This reaction was inhibited by vanillin. The oxidation of dihydrorhodamine 123 to fluorescent rhodamine 123 was also inhibited by vanillin. The kinetics of reaction between PON and vanillin was studied by stopped-flow technique. The products of this reaction were analyzed by HPLC, and hydroxyvanillin was identified as one of the five products with absorption at 350 nm. These data demonstrate that vanillin effectively scavenges PON in cell-free systems.
- Kumar, S. Santosh,Priyadarsini, K. Indira,Sainis, Krishna B.
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p. 139 - 145
(2007/10/03)
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- Water-soluble organotellurium compounds: Catalytic protection against peroxynitrite and release of zinc from metallothionein
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The antioxidant properties of a number of water-soluble diorganyl tellurides have been investigated. These organotellurium compounds efficiently protect against peroxynitrite-mediated oxidation of dihydrorhodamine 123, hydroxylation of benzoate, and nitra
- Jacob, Claus,Arteel, Gavin E.,Kanda, Takahiro,Engman, Lars,Sies, Helmut
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- Rhodanol Synthons for Fluorescent Labeling and Drug Conjugates
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The synthesis of Rhodanol derivatives 1b-1j is described.Rhodamine 123 was reduced to the corresponding alcohol and after acetylation of the amino functionalities, the protected Rhodanol was further derivatized by alkylation with oxirane, chloromethyloxirane and 2-acetoxyethoxymethylchloride.The coupling of some synthons to FU and FUrd at different conditions was studied.Synthons 1a, 1b and 1f were converted to phosphoramidites and used for 5'-labeling of oligonucleotides as a final step in solid-phase synthesis on automated DNA synthesizer.
- Spassova, Maria,Kois, Pavol,Watanabe, Kyoichi
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p. S290 - S293
(2007/10/03)
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