InChI=1S/C19H16O8/c1-26-16-9-12(2-5-13(16)20)10-17(19(24)25)27-15-6-3-11(8-14(15)21)4-7-18(22)23/h2-10,20-21H,1H3,(H,22,23)(H,24,25)/b7-4+,17-10-