Rifamycin O

4-O-(carboxymethyl)-1-deoxy-1,4-dihydro-4-hydroxy-1-oxo-, gamma-lactone; Spiro[1,3-dioxolane-2,9′(6′H)-[2,7](epoxypentadeca[1,11,13]trienimino)naphtho[2,1-b]furan], rifamycin deriv. (ZCI),[(7'S,9'E,11'S,12'R,13'S,14'R,15'R,16'R,17'S,18'S,19'E,21'Z)-2',15',17'-trihydroxy-11'-methoxy-3',7',12',14',16',18',22'-heptamethyl-4,6',23',29'-tetraoxospiro[1,3-dioxolane-2,27'-8,30-dioxa-24-azatetracyclo[23.3.1.14,7.05,28]triaconta-1(28),2,4,9,19,21,25-heptaene]-13'-yl] acetate,Rifamycin