InChI=1S/C21H20O9/c1-10-5-12(22)8-15(23)18(10)20(28)30-21(2)16(24)7-11-6-13(3-4-17(25)26)29-9-14(11)19(21)27/h3-6,8,16,22-24H,7,9H2,1-2H3,(H,25,26)/b4-3+/t16-,21+/m1/s1