The Synthesis and Xanthine Oxidase Inhibitory Activity of Pyrazolo[3, 4-d]pyrimidines

A series of compounds possessing the pyrazolo[3, 4-d]pyrimidine nucleus were synthesized, characterized and screened for the ability to inhibit xanthine oxidase activity. The compounds were compared with 4-hydroxypyrazolo[3, 4-d]pyrimidine (4), which showed 100% inhibition at a 33 μmole concentration. The structure-activity relationships of the synthesized compounds were discussed. 4-Amino-6-hydroxy-3-phenyl-pyrazolo[3, 4-d]pyrimidine (30b) and 4-amino-3-(p-chlorophenyl)-6-hydroxypyrazolo[3, 4-d]pyrimidine (30c) were found to be as potent inhibitors as allopurinol.