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Stability of 7,8‐Dihydropterins in Air‐Equilibrated Aqueous Solutions
Author(s) -
Dántola M. Laura,
Vigi Mariana,
Capparelli Alberto L.,
Lorente Carolina,
Thomas Andrés H.
Publication year - 2008
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.200890046
Subject(s) - chemistry , pterin , autoxidation , aqueous solution , yield (engineering) , moiety , reaction rate constant , medicinal chemistry , organic chemistry , kinetics , materials science , physics , cofactor , quantum mechanics , metallurgy , enzyme
6‐Substituted 7,8‐dihydropterins (=2‐amino‐7,8‐dihydropteridin‐4(1 H )‐ones) are heterocyclic compounds that occur in a wide range of living systems and participate in relevant biological functions. In air‐equilibrated aqueous solutions, these compounds react with dissolved O 2 (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 O 2 at 25° and 40° are reported. The biological implications of the results obtained are also discussed.