InChI=1S/C20H20O7/c1-20(2,26)6-5-12-14(23)8-17-18(19(12)25)15(24)9-16(27-17)11-4-3-10(21)7-13(11)22/h3-4,7-9,21-23,25-26H,5-6H2,1-2H3