InChI=1S/C21H22O9/c1-12-14(22)9-10-27-20(12)30-21-19(26)18(25)17(24)15(29-21)11-28-16(23)8-7-13-5-3-2-4-6-13/h2-10,15,17-19,21,24-26H,11H2,1H3/b8-7+