InChI=1S/C20H20O7/c1-9-7-12(16-13(22)3-2-4-14(16)23)18(20(26)27)17(19(9)25)11-6-5-10(21)8-15(11)24/h2-8,12,17-19,21-25H,1H3,(H,26,27)