InChI=1S/C17H17NO7S/c19-14-5-1-12(2-6-14)9-10-18-17(21)8-4-13-3-7-15(20)16(11-13)25-26(22,23)24/h1-8,11,19-20H,9-10H2,(H,18,21)(H,22,23,24)/b8-4+