New Results on the Photochemistry of Biopterin and Neopterin in Aqueous Solution
作者:Mariana Vignoni、Franco M. Cabrerizo、Carolina Lorente、Andrés H. Thomas
DOI:10.1111/j.1751-1097.2008.00450.x
日期:2009.1
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 interest because the photolysis of this compound takes place in the white skin patches of patients affected by vitiligo. The photochemical reactions were
i.e., 6-(1′-hydroxy) derivatives 1 and 2, methyl derivatives 3 – 7, and 6-(1′-oxo) derivatives 8– 10. All but the 6-(1′-oxo) derivatives produced hydroxyl radicals, as measured by the amount of salicylicacid hydroxylation products. This amount was dependent on the stability of the dihydropterin used. In the presence of chelated iron ions, hydroxylation was increased in every case; even 6-(1′-oxo)
Reaction between 7,8-dihydropterins and hydrogen peroxide under physiological conditions
作者:M. Laura Dántola、Tobias M. Schuler、M. Paula Denofrio、Mariana Vignoni、Alberto L. Capparelli、Carolina Lorente、Andrés H. Thomas
DOI:10.1016/j.tet.2008.07.005
日期:2008.9
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 degrees C in neutral aqueous solutions are reported. The biological implications of the results obtained are also discussed. (c) 2008 Elsevier Ltd. All rights reserved.