Final answer:
6-Mercaptopurine, Azathioprine, and 6-thioguanine act as antimetabolites that disrupt purine nucleotide synthesis and incorporate into DNA and RNA, impairing their function and inhibiting rapidly dividing cells like cancer cells.
Step-by-step explanation:
The mechanism of action of 6-mercaptopurine (6-MP), Azathioprine, and 6-thioguanine (6-TG) involves their role as antimetabolites in purine and nucleic acid metabolism, which is crucial for DNA and RNA synthesis. These drugs are analogs of purine bases and become incorporated into the DNA and RNA, causing faulty base pairing and inhibition of cell division—primarily affecting rapidly dividing cells such as cancer cells. Specifically, 6-MP is metabolized into its ribonucleotide form, which inhibits the conversion of inosinic acid to adenine nucleotides, leading to a decrease in adenine availability and subsequent interference with nucleic acid synthesis. Additionally, it is incorporated as thioguanosine into DNA and RNA, disrupting proper protein synthesis. Azathioprine is a prodrug of 6-MP, and 6-TG operates similarly by being incorporated into DNA, resulting in disruption of vital functions of nucleic acids.