Some observations on the reduction of iron by tissue extracts and by ascorbic acid, with a note on the stabilization of ascorbic acid solutions

Abstract

The ability of ascorbic acid to reduce, at different pH''s, ionic iron, iron in combination with lactic acid, glutamic acid or protein was detd. At pH 7.4 only the Fe in protein combination (lecitho-vitellin) was reduced, thus indicating that the reduction of tissue iron in-vivo by ascorbic acid must involve some form of iron-protein complex. The relative capacity of extracts of several tissues to reduce Fe''" and 2:6 dichloro-phenolindophenol was measured. The catalysis of ascorbic acid oxidation by Cu was inhibited by the following substances in order of decreasing activity, Na di-ethyldithiocarbamate, cystine, cysteine and glutathione; but not by taurine or glycine. The aerobic oxidation of ascorbic acid in orange juice was inhibited by adding aa'' dipyridyl and Na diethyldithiocarbamate together. It was not affected by adding the carbamate reagent alone but may actually be accelerated by the single addition of dipyridyl.