Thermal degradation of (6R,S)-5,10-methenyltetrahydrofolate in aqueous solution at pH 8

The degradation of the folate (6R,S)-5,10-methenyltetrahydrofolate chloride (MTHF-Cl) in aqueous solution at pH 8 at room temperature is studied by absorption spectra measurements. Samples with and without the reducing agent β-mercaptoethanol (β-ME) both under aerobic and anaerobic conditions are investigated. MTHF-Cl hydrolyses to (6R,S)-10-formyltetrahydrofolate (10-HCO-H4folate) in all four cases. 10-HCO-H4folate oxidizes to 10-formyldihydrofolate (10-HCO-H2folate) under aerobic conditions in the absence of β-ME. The degradation dynamics is analysed theoretically and conversion rate constants of hydrolysis and oxidation are determined.