The Diabetogenic Effect of Dehydroascorbic and Dehydroisoascorbic Acids*

The chemical properties of these two substances are strikingly similar. Both compounds are irreversibly decomposed under biological conditions. Alloxan has a half life of 1 minute (1) and dehydroascorbic acid has a half life of a few minutes (2). Alloxan is readily reduced to dialuric acid (3) with which it forms alloxantin (3). Dehydroascorbic acid is readily reduced to ascorbic acid (4) and also forms a similar intermediate compound (5). Alloxan (6) and dehydroascorbic acid (7) both form addition compounds with molecules containing the sulfhydryl group. Alloxan (8) and dehydroascorbic acid (9) both produce the Strecker reaction with amino acids and give the ordinary ketone reactions. It would appear logical, therefore, to expect that there might be a relationship between alloxan and dehydroascorbic acid with regard to the production of diabetes. There is some evidence suggesting that dehydroascorbic acid may have diabetogenic properties. It is known that the dehydroascorbic acid level in the scorbutic animal is higher than normal, t,he dehydroascorbic acid-ascorbic acid ratio being as much as 20 times the normal value (10). Correlated with this is the fact that scorbutic guinea pigs have a decreased glucose tolerance (11) and show degeneration of the islets of Langerhans (12). Furthermore, ascorbic acid is known to act synergistically with alloxan (13, 14) and it seems probable that this effect