The molecule is an organic anion obtained by selective deprotonation of the hydroxy groups at positions 2 and 2' of nicotine blue; major species at pH 7.3 (according to Marvin v 6.2.0.). It is a conjugate base of a nicotine blue.
6-oxo-3-(2,5,6-trioxopyridin-3-yl)-1H-pyridine-2,5-diolate