Using O=C(CCC(Cc1ccc(C(=O)O)cc1)C(=O)O)NOCc1ccccc1 to produce O=C(CCC(Cc1ccc(C(=O)[O-])cc1)C(=O)O)NO, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.