InChI=1S/C21H20O8/c22-10-16-18(24)19(25)20(26)21(29-16)28-14-8-4-7-13-17(14)12(23)9-15(27-13)11-5-2-1-3-6-11/h1-9,16,18-22,24-26H,10H2