[{"from": "human", "value": "What can you tell me about this molecule? [C][C][C][C][C][Branch1][Branch1][C][C][Ring1][=Branch1][N][C][=Branch1][C][=O][N][Branch1][Ring2][C][C][Cl][N][=O]"}, {"from": "gpt", "value": "The molecule is a methylated derivative of carmustine with antineoplastic activity. As an alkylating agent, semustine forms covalent linkages with nucleophilic centers in DNA, causing depurination, base-pair miscoding, strand scission, and DNA-DNA cross-linking, which may result in cytotoxicity. (NCI04)"}]