The molecule is a phenolate anion obtained by deprotonation of the 5-hydroxy group of rifamycin SV. It is the major microspecies at pH 7.3 (according to Marvin v 6.2.0.). It is a conjugate base of a rifamycin SV.
(7S,9E,11S,12R,13S,14R,15R,16R,17S,18S,19E,21Z)-13-acetyloxy-15,17,27,29-tetrahydroxy-11-methoxy-3,7,12,14,16,18,22-heptamethyl-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-2-olate