InChI=1S/C20H20O8/c1-26-16-9-12(3-6-14(16)21)5-8-19(23)28-18(20(24)25)11-13-4-7-15(22)17(10-13)27-2/h3-10,18,21-22H,11H2,1-2H3,(H,24,25)/b8-5+/t18-/m0/s1