InChI=1S/C21H22O8/c1-27-14-9-13(8-7-12-5-3-2-4-6-12)10-15(11-14)28-21-18(24)16(22)17(23)19(29-21)20(25)26/h2-11,16-19,21-24H,1H3,(H,25,26)/b8-7+