Study of Reversible Oxidation of Adrenaline and Its Derivatives.

Abstract

Ephedrine, adrenalone, methylacetopyrocateehol, dimethylacetopyrocatechol, adrenaline, the ethyl and methyl ethers and the anhydride of adrenaline were investigated to see whether (a) they would be oxidized by dibromophenolindophenol, naphtholidichloroindophenol, methylene blue and indigo carmine; (b) whether the oxidized forms would act as oxidizing agents with reduced indigo; (c) whether they formed reversible oxidation-reduction systems; (d) whether under any conditions they would function as cyclic cataclysts.

All of the eight substances, except ephedrine, are oxidized by dibromophenolindophenol. Adrenaline and its ether derivatives are oxidized by only the last mentioned oxidizing dye. Adrenalone, methylacteopyrocatechol, and dimethylacetopyrocatechol are oxidized by naphtholdichloroindophenol and indigo carmine. Adrenalone and methylaminoacetopyrocatechol are oxidized by all of the dyes. Dimethylacetopyrocatechol is not oxidized by methylene blue, but is oxidized by indigo carmine. These results emphasize the fact that the configuration of the oxidizing dyes is of greater importance than the intensity of oxidation produced by the dye.

Adrenalone, methyl and dimethylacetopyrocatechol will oxidize reduced indigo after they have been oxidized with the dyes. The oxidation is quantitatively reversible. Adrenaline and its ethers cannot be reversibly oxidized. The probable point of attack of the oxidizing agent in all of these compounds is the two hydroxyl groups on the benzene ring, with the formation of an ortho-quinone. This derivative of adrenalone can be reduced, but, with adrenaline some other part of the molecule absorbs the oxidizing power of the ortho-quinone, resulting in an irreversible reaction. At a pH of 7.4 and in the presence of a third component, adrenaline will act as a cyclic catalyst bringing about the oxidation of adrenaline with molecular oxygen. The essential configuration of the third component has not been determined, but it is prepared by the action of sodium hydroxide on glucose.