InChI=1/C21H24O8/c1-27-15-8-13(3-2-12-4-6-14(23)7-5-12)9-16(10-15)28-21-20(26)19(25)18(24)17(11-22)29-21/h2-10,17-26H,11H2,1H3/b3-2+