The molecule is a hydroxy monocarboxylic acid anion arising from deprotonation of the carboxy and 5-carboxy groups of rifamycin B; major species at pH 7.3. It is a conjugate base of a rifamycin B.
2-[[(7S,9E,11S,12R,13S,14R,15R,16R,17S,18S,19E,21Z)-13-acetyloxy-15,17,29-trihydroxy-11-methoxy-3,7,12,14,16,18,22-heptamethyl-2-oxido-6,23-dioxo-8,30-dioxa-24-azatetracyclo[23.3.1.14,7.05,28]triaconta-1(29),2,4,9,19,21,25,27-octaen-27-yl]oxy]acetate