Structure of Thioguanine
Thioguanine, also known as 6-thioguanine (6-TG), is a purine analog with the following structural features:
Purine Base: Similar to guanine.
Thio Group: Contains a sulfur atom replacing the oxygen at position 6.
Amino Group: Contains an amino group at position 2.
Chemical Formula: C₅H₄N₄OS
Mode of Action
Thioguanine acts as an antimetabolite by:
Incorporation into DNA and RNA: Disrupts nucleic acid synthesis and function.
Inhibition of Purine Synthesis Enzymes: Blocks enzymes involved in purine nucleotide synthesis.
Induction of Apoptosis: Causes cytotoxicity in rapidly dividing cells, particularly in leukemic cells.
Uses
Acute Lymphoblastic Leukemia (ALL): Often used in combination with other chemotherapeutic agents.
Chronic Myeloid Leukemia (CML): As part of certain treatment regimens.
Inflammatory Bowel Disease (IBD): Such as Crohn's disease and ulcerative colitis (off-label).
Autoimmune Disorders: Including rheumatoid arthritis (off-label)..