InChI=1S/C20H18O8/c1-26-16-10-13(3-6-14(16)21)11-18(20(24)25)28-15-7-4-12(5-8-19(22)23)9-17(15)27-2/h3-11,21H,1-2H3,(H,22,23)(H,24,25)/b8-5-,18-11+