Which of the following is NOT a subcategory of alkylating agents?

Alkylating agents are a class of chemotherapy drugs that work primarily by adding an alkyl group to the DNA molecule, which can prevent cancer cells from dividing. They are categorized into several subgroups based on their chemical structure and mechanism of action.

Nitrosoureas and nitrogen mustards are well-established subcategories of alkylating agents. Nitrosoureas, such as carmustine and lomustine, are unique because they can cross the blood-brain barrier and are often used in the treatment of brain tumors. Nitrogen mustards, including cyclophosphamide and mechlorethamine, are some of the earliest developed alkylating agents.

Platinum-based agents, such as cisplatin and carboplatin, although they have a structure that incorporates a platinum atom, do not fit into the category of alkylating agents. Instead, they form cross-links between DNA strands in a different manner, thereby inhibiting DNA replication and transcription.

Nonselective agents, as a description, do not constitute a specific subcategory of alkylating agents. The term generally refers to agents that may affect a wide variety of cells, rather than targeting a defined pathway or cell type, making it less relevant in the context of specific