InChI=1S/C18H18N2O8/c1-6-12-8(2-3-19-6)11-9(20-12)4-7(5-10(11)21)27-18-15(24)13(22)14(23)16(28-18)17(25)26/h2-5,13-16,18,20-24H,1H3,(H,25,26)