O=C1NC(=O)C(O)C(=O)N1    mol34232    0_1
O=c1[nH]c(=O)[c-](O)c(=O)[nH]1    mol34232    -1_1
O=C1[N-]C(=O)C(O)C(=O)N1    mol34232    -1_2
O=C1NC(=O)C([O-])C(=O)N1    mol34232    -1_3