InChI=1S/C21H20O9/c22-9-16-18(25)19(26)20(27)21(30-16)28-12-5-6-13-14(8-12)29-15(17(13)24)7-10-1-3-11(23)4-2-10/h1-8,16,18-23,25-27H,9H2/b15-7-