Inhibition of ferritin reduction by pyrazolo(3,4d)pyrimidines

The characteristics of inhibition of the ferritin reductase function of xanthine oxidase by three pyrazolopyrimidines is described. Under anaerobic conditions, the ferritin reduction coupled to hypoxanthine oxidation was inhibited by the three pyrazolopyrimidines tested, 4-hydroxypyrazolopyrimidine, 4,6-dihydroxypyrazolopyrimidine, and 4-mercaptopyrazolopyrimidine. Under the same conditions, four purine analogs were devoid of inhibitory activity, and 8-azaguanine and 8-azaadenine were weakly inhibitory.