InChI=1S/C19H20O8S/c1-11(2)3-6-14-15(20)7-12(8-16(14)21)4-5-13-9-17(22)19(18(23)10-13)27-28(24,25)26/h3-11,20-23H,1-2H3,(H,24,25,26)/b5-4+,6-3+