InChI=1S/C19H20O8S/c1-10(2)18-19(26-18)17-14(21)7-12(8-15(17)22)4-3-11-5-6-13(20)16(9-11)27-28(23,24)25/h3-10,18-22H,1-2H3,(H,23,24,25)/b4-3+