Lumazine is one of the biologically-significant pteridine compounds which may participate in biochemical redox reactions. The present work focuses on the reactive intermediates involved in the redox processes of lumazine to better understand its potential physiological action. Two reactive intermediates are produced during the reduction and re-oxidation of lumazine, as revealed by cyclic voltammetry and voltabsorptometry. The stability of the intermediates is highly pH-dependent. Lumazine can be fully regenerated along a circular redox mechanism involving two electrochemical and two chemical steps. The chemical conversion of the intermediates can be distinguished from the electrochemical steps on the time-derivative cyclic voltabsorptiograms recorded at an appropriate wavelength. (c) 2017 Elsevier B.V. All rights reserved.