InChI=1S/C20H18O8/c1-27-17-9-11(3-5-15(17)21)7-13(19(23)24)14(20(25)26)8-12-4-6-16(22)18(10-12)28-2/h3-10,21-22H,1-2H3,(H,23,24)(H,25,26)/b13-7-,14-8+