InChI=1/C21H22O9/c1-28-14-6-4-11(5-7-14)2-3-12-8-13(22)10-15(9-12)29-21-18(25)16(23)17(24)19(30-21)20(26)27/h2-10,16-19,21-25H,1H3,(H,26,27)/b3-2+