Natural reversible oxidation-reduction systems as accessory catalysts in respiration: juglon and lawson

Abstract

Lawson (2-hydroxynaphthoquinone), the coloring material contained in the leaves of the henna plant (Lawsonia inermis), and juglon (5-hydroxynaph-thoquinone), the coloring material contained in the husks of walnuts, both form leuco-compounds when exposed to the influence of various reducing agents. The leuco-compounds at once regenerate the pigment in contact with molecular oxygen. Thus they fulfil one of the main conditions which might enable them to play a part in cell-respiration by acting as autoxidizable acceptors of H. This paper deals with the effect of juglon and lawson on cell-respiration, the establishment of the oxidation-reduction potentials of both substances and the correlation of the 2 series of results.