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