InChI=1S/C21H20O7/c1-10(2)4-6-12-14(23)9-16-17(18(12)25)19(26)21(27-3)20(28-16)11-5-7-13(22)15(24)8-11/h4-5,7-9,22-25H,6H2,1-3H3