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