Production of Stable Solutions of 7,8-Dihydropterin

Abstract

In aqueous solution, 7,8-dihydropterin is hydrated to 6-hydroxy-5,6,7,8-tetrahydropterin. At neutral pH the equilibrium between these two species lies predominantly towards 7,8-dihydropterin, but autoxidation of 6- hydroxy-5,6,7,8-tetrahydropterin to 7,8-dihydroxanthopterin disrupts the equilibrium resulting in further 7,8- dihydropterin hydration. Oxidation of 5,6,7,8-tetrahydropterin, at pH 6.8, by ferricyanide or dichlorophenolindolphenol, followed by a period of time for quinonoid dihydropterin rearrangement, is shown to result in a solution consisting predominantly of 7,8-dihydropterin. At 37 °C, the 7,8-dihydropterin content rapidly decreases with a corresponding increase in 7,8-dihydroxanthopterin. Addition of dithioerythritol to a 7,8- dihydropterin solution prevents 6-hydroxy-5,6,7,8-tetrahydropterin oxidation, resulting in a stable solution consisting predominantly of 7,8-dihydropterin.