InChI=1S/C18H18O9/c1-2-3-6-9-8-5-4-7-10(11(8)17(24)25-9)26-18-14(21)12(19)13(20)15(27-18)16(22)23/h2,4-7,12-15,18-21H,1,3H2,(H,22,23)/b9-6+