- Reaction between 7,8-dihydropterins and hydrogen peroxide under physiological conditions
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In vitiligo, a common skin disorder that produces white patches of depigmentation, 7,8-dihydropterins accumulate in the presence of high concentration of H2O2. In this work, we present a study of the reaction between 7,8-dihydropterins and H2O2. The rate of the reaction, as well as the products formed, strongly depend on the chemical structure of the substituents. Electron-donor groups as substituents are the most reactive derivatives and undergo oxidation of the pterin moiety. The corresponding bimolecular rate constants at 37 °C in neutral aqueous solutions are reported. The biological implications of the results obtained are also discussed.
- Laura Dántola,Schuler, Tobias M.,Paula Denofrio,Vignoni, Mariana,Capparelli, Alberto L.,Lorente, Carolina,Thomas, Andrés H.
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- New results on the photochemistry of biopterin and neopterin in aqueous solution
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New photochemical studies of the reactivity of biopterin (BPT) and neopterin (NPT) in acidic (pH = 5.5) and alkaline (pH = 10.5) aqueous solutions at 350 nm and room temperature were performed. The photochemical properties of BPT are of particular interes
- Vignoni, Mariana,Cabrerizo, Franco M.,Lorente, Carolina,Thomas, Andres H.
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- Stability of 7,8-dihydropterins in air-equilibrated aqueous solutions
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6-Substituted 7,8-dihydropterins (=2-amino-7,8-dihydropteridin-4(1H)-ones) are heterocyclic compounds that occur in a wide range of living systems and participate in relevant biological functions. In airequilibrated aqueous solutions, these compounds react with dissolved O2 (autooxidation). The rates of these reactions as well as the products formed strongly depend on the chemical structure of the substituents. 7,8-Dihydro-6-methylpterin and 7,8-dihydro-6,7-dimethylpterin that bear electron-donor groups as substituents are the most reactive derivatives and undergo oxidation of the pterin moiety to yield the corresponding oxidized derivatives (6-methylpterin and 6,7-dimethylpterin, resp.). The oxidations of 7,8-dihydrobiopterin, 7,8-dihydroneopterin, and 7,8-dihydrofolic acid are slower, and they yield 7,8-dihydroxanthopterin as the main product. 7,8-Dihydroxanthopterin, 6-formyl-7,8-dihydropterin, and sepiapterin are rather stable, and their consumption in air-equilibrated solutions is negligible for several days. The pseudo-first-order rate constants of the reactions between these compounds and O2 at 25° and 40° are reported. The biological implications of the results obtained are also discussed.
- Dantola, M. Laura,Vignoni, Mariana,Capparelli, Alberto L.,Lorente, Carolina,Thomas, Andres H.
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p. 411 - 425
(2009/02/07)
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