InChI=1/C16H16O8/c17-10-3-1-8(5-11(10)18)2-4-14(20)24-13-7-9(16(22)23)6-12(19)15(13)21/h1-6,12-13,15,17-19,21H,7H2,(H,22,23)/b4-2+