Photolysis of Folic Acid and 6-Formylpterin in Acid Aqueous solutions

ANDRES H. THOMAS; GUSTAVO SUÁREZ; FRANCO M. CABRERIZO; RAUL MARTINO; ALBERTO L. CAPPARELLI

Dresden, Alemania

Simposio; XVIII IUPAC Simposium on phochemistry; 2000

Folic acid and 6-formylpterin solutions of pH in the range 4.5–6.0 were photolysed at 350 nm at room temperature. The photochemical reactions were followed by UV–VIS spectrophotometry, thin layer chromatography (TLC) and high performance liquid chromatography (HPLC). In the presence of oxygen, folic acid is photochemically cleavaged yielding 6-formylpterin and p-aminobenzoylglutamic acid. As the photolysis proceeds, 6-carboxypterin arises from 6-formylpterin, as observed when solutions only containing the latter compound are irradiated in the presence of oxygen. In the absence of oxygen, folic acid is not light-sensitive. However, when oxygen free solutions of 6-formylpterin are irradiated, a ‘red intermediate’ is observed, which is thermally oxidised producing 6-carboxypterin on admission of oxygen. The quantum yields of substrates disappearance and of photoproducts formation are reported.