InChI=1S/C19H20O9/c20-11-8-10(7-6-9-4-2-1-3-5-9)27-19(26)12(11)16-14(22)13(21)15(23)17(28-16)18(24)25/h1-7,10,12-17,21-23H,8H2,(H,24,25)/b7-6+