Synthetic substances called purine nucleoside analogs are made to resemble the structure of the naturally occurring purine nucleosides, which are crucial parts of DNA and RNA. These analogues have a number of medical uses, especially in the management of cancer and viral infections. Purine nucleoside analogs, which are made up of a purine base joined to a ribose sugar by a glycosidic link, are structurally comparable to natural purine nucleosides like adenine and guanine. They do, however, have certain changes that give them special qualities, such greater potency or resistance to enzymatic breakdown.Acyclovir is one of the most well-known purine nucleoside analogs and is used to treat infections caused by the herpes simplex virus. Viral thymidine kinase specifically phosphorylates acyclovir to its active form, which inhibits viral DNA polymerase and stops the production of new viral DNA.Azathioprine is a significant purine nucleoside analog that is used as an immunosuppressant to treat autoimmune conditions including rheumatoid arthritis and prevent organ transplant rejection. The body breaks down azathioprine into 6-mercaptopurine, which disrupts purine metabolism and prevents rapidly proliferating cells—including immune cells—from synthesizing DNA and RNA.By interfering with the synthesis of DNA in leukemia cells, mercaptopurine and its prodrug thioguanine are also employed in the treatment of leukemia, namely acute lymphoblastic leukemia (ALL).A purine nucleoside analog called cladribine is used to treat multiple sclerosis and hairy cell leukemia. Deoxycytidine kinase phosphorylates it, which then prevents DNA synthesis by interfering with DNA repair processes.Another purine nucleoside analog used to treat specific forms of lymphomas and chronic lymphocytic leukemia (CLL) is fludarabine. Deoxycytidine kinase phosphorylates it, and it prevents DNA synthesis by blocking ribonucleotide reductase and DNA polymerase.A purine nucleoside analog called pentostatin is used to treat hairy cell leukemia. Deoxyadenosine triphosphate (dATP) builds up to dangerous amounts in lymphocytes due to the inhibition of adenosine deaminase, an enzyme involved in purine metabolism. This ultimately results in cell death.To sum up, purine nucleoside analogs are artificial substances that have structural characteristics with purine nucleosides found in nature. Because they interfere with target cells' ability to synthesize DNA and RNA, they have a wide range of medical uses, including the treatment of cancer and viral infections. These substances are essential to modern medicine because they provide efficient cures for a wide range of illnesses.
