Purine analogues are

antimetabolite An antimetabolite is a chemical that inhibits the use of a metabolite, which is another chemical that is part of normal metabolism. Such substances are often similar in structure to the metabolite that they interfere with, such as the antifolat ...

s that mimic the structure of metabolic

purine Purine is a heterocyclic aromatic organic compound that consists of two rings (pyrimidine and imidazole) fused together. It is water-soluble. Purine also gives its name to the wider class of molecules, purines, which include substituted puri ...

Examples

Nucleobase analogue Nucleic acid analogues are compounds which are Analog (chemistry), analogous (structurally similar) to naturally occurring RNA and DNA, used in medicine and in molecular biology research. Nucleic acids are chains of nucleotides, which are compo ...

s **

Thiopurine The thiopurine drugs are purine antimetabolites widely used in the treatment of acute lymphoblastic leukemia, autoimmune disorders (e.g., Crohn's disease, rheumatoid arthritis), and organ transplant recipients. Metabolism is catalyzed by S-met ...

s such as thioguanine are used to treat acute leukemias and remissions in acute granulocytic leukemias. ***

Azathioprine Azathioprine, sold under the brand name Imuran, among others, is an immunosuppressive medication. It is used for the treatment of rheumatoid arthritis, granulomatosis with polyangiitis, Crohn's disease, ulcerative colitis, and systemic lupus er ...

is the main immunosuppressive cytotoxic substance. A prodrug, it is widely used in transplantation to control rejection reactions. It is nonenzymatically cleaved to

mercaptopurine Mercaptopurine (6-MP), sold under the brand name Purinethol among others, is a medication used for cancer and autoimmune diseases. Specifically it is used to treat acute lymphocytic leukemia (ALL), acute promyelocytic leukemia (APL), Crohn's d ...

, a purine analogue that inhibits DNA synthesis. By preventing the clonal expansion of lymphocytes in the induction phase of the immune response, it affects both

cell immunity Cell most often refers to: * Cell (biology), the functional basic unit of life * Cellphone, a phone connected to a cellular network * Clandestine cell, a penetration-resistant form of a secret or outlawed organization * Electrochemical cell, a de ...

and

humoral immunity Humoral immunity is the aspect of immunity (medical), immunity that is mediated by macromolecules – including secreted antibodies, complement proteins, and certain antimicrobial peptides – located in extracellular fluids. Humoral immunity is ...

. It also successfully suppresses

autoimmunity In immunology, autoimmunity is the system of immune responses of an organism against its own healthy cells, tissues and other normal body constituents. Any disease resulting from this type of immune response is termed an " autoimmune disease ...

. ***

Mercaptopurine Mercaptopurine (6-MP), sold under the brand name Purinethol among others, is a medication used for cancer and autoimmune diseases. Specifically it is used to treat acute lymphocytic leukemia (ALL), acute promyelocytic leukemia (APL), Crohn's d ...

*** Thioguanine *

Nucleoside analogue Nucleoside analogues are structural analogues of a nucleoside, which normally contain a nucleobase and a sugar. Nucleotide analogues are analogues of a nucleotide, which normally has one to three phosphates linked to a nucleoside. Both types ...

s **

Clofarabine Clofarabine is a purine nucleoside antimetabolite marketed in the United States and Canada as Clolar. In Europe and Australia/New Zealand the product is marketed under the name Evoltra. It is FDA-approved for treating relapsed or refractory a ...

Pentostatin Pentostatin (or 2′-deoxycoformycin, trade name Nipent, manufactured by SuperGen) is an anticancer chemotherapeutic drug. Medical uses Pentostatin is used to treat hairy cell leukemia. It is given by intravenous infusion once every two weeks ...

and

cladribine Cladribine, sold under the brand name Leustatin, among others, is a medication used to treat hairy cell leukemia (formally named leukemic reticuloendotheliosis) and B-cell chronic lymphocytic leukemia. Cladribine, sold under the brand name Mav ...

are adenosine analogs that are used primarily to treat

hairy cell leukemia Hairy cell leukemia is an uncommon hematological malignancy characterized by an accumulation of abnormal B lymphocytes. The incidence of hairy cell leukemia (HCL) is 0.28-0.30 cases per 100,000 people in Europe and the United States and the pre ...

. *Nucleotide analogues **

Fludarabine Fludarabine is a purine analogue and antineoplastic agent. It is generally used as its 5-O-phosphorylated form known as fludarabine phosphate, sold under the brand name Fludara among others. It is a chemotherapy medication used in the treatm ...

inhibits multiple

DNA polymerase A DNA polymerase is a member of a family of enzymes that catalyze the synthesis of DNA molecules from nucleoside triphosphates, the molecular precursors of DNA. These enzymes are essential for DNA replication and usually work in groups to create t ...

DNA primase DNA primase is an enzyme involved in the replication of DNA and is a type of RNA polymerase. Primase catalyzes the synthesis of a short RNA (or DNA in some living organisms) segment called a primer complementary to a ssDNA (single-stranded ...

, and

DNA ligase I DNA ligase 1 also DNA ligase I, is an enzyme that in humans is encoded by the ''LIG1'' gene. DNA ligase 1 is the only known eukaryotic DNA ligase involved in both DNA replication and repair, making it the most studied of the ligases. Discovery ...

, and is

S phase S phase (Synthesis phase) is the phase of the cell cycle in which DNA is replicated, occurring between G1 phase and G2 phase. Since accurate duplication of the genome is critical to successful cell division, the processes that occur during S ...

-specific (since these enzymes are highly active during DNA replication). File:Purine.png,

Purine Purine is a heterocyclic aromatic organic compound that consists of two rings (pyrimidine and imidazole) fused together. It is water-soluble. Purine also gives its name to the wider class of molecules, purines, which include substituted puri ...

File:Mercaptopurine.svg,

File:Tioguanine.svg, Thioguanine File:Fludarabine phosphate.svg,

Medical uses

Purine antimetabolites are commonly used to treat cancer by interfering with DNA replication.

References

Antimetabolites * {{biochem-stub