InChI=1S/C16H18O9/c1-7(14(20)21)5-8-3-2-4-9(6-8)24-16-12(19)10(17)11(18)13(25-16)15(22)23/h2-6,10-13,16-19H,1H3,(H,20,21)(H,22,23)/b7-5+