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