133633-12-2 3'-Hydroxy-5'-(4-propylpiperazinyl)benzoxazinorifamycin Krm 1657 Krm-1657 Rifamycin VIII, 1',4-didehydro-1-deoxy-1,4-dihydro-3'-hydroxy-1-oxo-5'-(4-propyl-1-piperazinyl)-