InChI=1S/C20H18O11/c21-12-4-1-10(7-14(12)23)3-6-16(25)31-17(18(26)27)20(30,19(28)29)9-11-2-5-13(22)15(24)8-11/h1-8,17,21-24,30H,9H2,(H,26,27)(H,28,29)/b6-3+