InChI=1S/C20H26O13/c21-7-20(29)8-31-19(17(20)28)30-6-12-14(25)15(26)16(27)18(32-12)33-13(24)4-2-9-1-3-10(22)11(23)5-9/h1-5,12,14-19,21-23,25-29H,6-8H2/b4-2+