InChI=1S/C20H18O7/c1-20(2)16(24)5-10-3-9(4-14(23)19(10)27-20)12-8-26-15-7-11(21)6-13(22)17(15)18(12)25/h3-4,6-8,16,21-24H,5H2,1-2H3