Abstract
From the experiments stated above, xanthurenic acid can unmis-takably inhibit hexokinase activity and it is highly possible to imagine that what has much to do with the inhibition may be either Mg_??_or -SH system. In either case, however, it is safe to consider that since glycosuria due to xanthurenic acid can be found to be identical with glycosuria caused by the action of alloxan, xanthurenic acid has been confirmed to be a diabetogenic substance.
1. Xanthurenic acid inhibits phosphorylation of hexose in rat liver.
2. It inhibits also animal and yeast hexokinase activity.
3. 4-OH-8-OCH3-quinolin-2-carboxylic acid, kynurenic acid, an-thranilic acid, 5-OH-anthranilic acid and cystein protect hexokinase activity against the inhibitive action of xanthurenic acid.
The authors wish to express their sincere thanks to Prof. Y. Kotake for his con-stamt encouragement and to Prof. K. Kodama for his kind revision and to Prof. K. Okunuki, Mr. K. Iwas a and Mr. F. Imamoto of the Department of Science of the Osaka University for their kind assistance in the preparation of hexokinase.
