InChI=1S/C20H18O9/c21-10-3-1-9(2-4-10)15-7-13(23)17-12(22)5-11(6-16(17)29-15)28-20-19(26)18(25)14(24)8-27-20/h1-7,14,18-22,24-26H,8H2