InChI=1/C20H22O9/c21-9-16-17(25)18(26)19(27)20(29-16)28-13-6-11(5-12(22)8-13)2-1-10-3-4-14(23)15(24)7-10/h1-8,16-27H,9H2/b2-1+/t16-,17-,18+,19-,20-/s2