1-((3',6'-Dihydroxy-3-oxo-3H-spiro[isobenzofuran-1,9'-xanthen]-5-yl)amino)-1-thioxo-5,8,11,14-tetraoxa-2-azaheptadecan-17-oic acid

1-((3',6'-Dihydroxy-3-oxo-3H-spiro[isobenzofuran-1,9'-xanthen]-5-yl)amino)-1-thioxo-5,8,11,14-tetraoxa-2-azaheptadecan-17-oic acid,