InChI=1S/C19H18O9/c20-13-9-12(8-11(26-13)7-6-10-4-2-1-3-5-10)27-19-16(23)14(21)15(22)17(28-19)18(24)25/h1-9,14-17,19,21-23H,(H,24,25)/b7-6+