InChI=1S/C21H22O9/c22-10-17-18(26)19(27)20(28)21(30-17)29-13-6-7-14(16(25)9-13)15(24)8-3-11-1-4-12(23)5-2-11/h1-9,17-23,25-28H,10H2/b8-3+