InChI=1S/C21H20O10/c1-8-17(26)18(27)19(28)21(29-8)31-16-7-11-13(24)5-10(22)6-15(11)30-20(16)9-2-3-12(23)14(25)4-9/h2-8,17-19,21,26-28H,1H3,(H3-,22,23,24,25)/p+1