13877-76-4 7H-Pyrazolo[4,3-d]pyrimidin-7-one, 1,4-dihydro-3-.beta.-D-ribofuranosyl- D-Ribitol, 1,4-anhydro-1-C-(6,7-dihydro-7-oxo-1H-pyrazolo[4,3-d]pyrimidin-3-yl)-, (S)- FORMYCIN B Laurusin NSC106486 Ohyamycin