16220-07-8 4-Hydroxy[3,4-d]pyrazolopyrimidine riboside 4H-Pyrazolo[3,4-d]pyrimidin-4-one, 1,5-dihydro-1-.beta.-D-ribofuranosyl- Allopurinol ribonucleoside Allopurinol riboside Allopurinol-1-ribonucleoside NSC138437