154-42-7

Odorless or almost odorless pale yellow crystalline powder.

6-THIOGUANINE(154-42-7) is incompatible with strong oxidizing agents. .

This chemical may be sensitive to prolonged exposure to air. Insoluble in water.

Flash point data for this chemical are not available; however, 6-THIOGUANINE is probably combustible.

An antineoplastic metabolic antagonist that inhibits DNA synthesis by being metabolically converted to 6-thioGMP. This inhibits purine biosynthesis at multiple steps, and may be phosphorylated and incorporated into DNA. In humans, it causes bone marrow depression and gastrointestinal toxicity. Due to safety problems it is currently less used as an antineoplastic agent but has some use as therapy for ulcerative colitis.

Crystalline, lyophilized, sterile, endot

Thioguanine,Burroughs-Wellcome,US,1966

6-Thioguanine acts as an antineoplastic and purine antimetabolite. It is also useful as an inhibition of stimulated expression of TNF-related apoptosis-inducing ligand (TRAIL) protein. It is involved in the treatment of acute leukemias and Psoriasis. Further, it is used for the treatment of ulcerative colitis and autoimmune diseases.

antineoplastic, purine antimetabolite

The compound produced dose-dependent inhibition of stimulated expression of TRAIL protein

Thioguanine USP (Tabloid)is used to treat acute leukemia; chronic granulocytic leukemia.

6-Thioguanine is a variant of guanine with hydrogen bonding at the N-7 of the purine ring. Its association with cytosine alters the dimension of the base stacking. 6-Thioguanine usage in treating inflammatory bowel disease (IBD) contributes to nodular regenerative hyperplasia (NRH) in the liver.
6-Thioguanine has been used:
to induce autophagy and apoptosis in colorectal cancer cell lines HCT116
as a selection marker in the mutation and survival assay in chinese hamster lung fibroblasts culture V79
as a selection marker in clonogenic Lung metastasis assay of 4T1-luc cells

ChEBI: A 2-aminopurine that is the 6-thiono derivative of 2-amino-1,9-dihydro-6H-purine.

6-Thioguanine is a purine analogue structurally related to 6-mercaptopurine and azathioprine. Thioguanine interferes with several enzymes required for de novo purine synthesis, and its metabolites are incorporated into DNA and RNA, further impeding nucleic acid synthesis. The mechanism of action of thioguanine in psoriasis is not clearly understood; it has been hypothesized to affect the proliferation and trafficking of lymphocytes as well as the proliferation of keratinocytes.

Thioguanine is an analogue of the natural purine guanine in which a hydroxyl group has been replaced by a sulfhydryl group in the 6-position. Two major mechanisms of cytotoxicity have been proposed for 6-thioguanine: (1) incorporation of the thio nucleotide analogue into DNA or RNA and (2) feedback inhibition of purine nucleotide synthesis.
The product of this reaction, 6-TGMP, can eventually be converted to deoxy-6-thioguanosine-triphosphate (dTGTP), which has been shown to be incorporated into DNA. Resistance of human leukemia cells to thioguanine has been correlated with decreased activity of HGPRTase and to increased inactivation of the thio nucleotides by alkaline phosphatase.
Thioguanine is slowly absorbed after oral administration; parent drug levels are barely detectable, and peak levels of metabolites occur only after 6 to 8 hours. Total urinary excretion of metabolites in the first 24 hours is 24 to 46% of the administered dose.
Thioguanine is used primarily as part of a combined induction of chemotherapy in acute myelogenous leukemia.
Myelosuppression, with leukopenia and thrombocytopenia appearing 7 to 10 days after treatment, and mild nausea are the most common adverse effects. Liver toxicity with jaundice has been reported in some patients but appears to be less common than with mercaptopurine.

A mixture of 2.7 grams of finely divided guanine, 10 grams of pulverized phosphorus pentasulfide, 10 ml of pyridine and 100 ml of tetralin was heated at 200°C with mechanical stirring for 5 hours. After cooling, the mixture was filtered and the insoluble residue treated with 150 ml of water and 50 ml of concentrated ammonium hydroxide. The ammoniacal solution was filtered, heated to boiling and acidified with acetic acid. Upon cooling, 2-amino-6- mercaptopurine precipitated as a dark yellow powder, according to US Patent 2,697,709.

Tioguanine is INN and BAN.

Cancer chemotherapy

Ribosylated and phosphorylated by the same pathway as natural purine bases; as the nucleotide, inhibits a variety of cellular processes involved in nucleic acid synthesis. Has a long history as an effective treatment of leukemia.

Absorption of orally administered 6-thioguanine is slow and incomplete; only approximately 30% of the oral dose is achieved in the plasma, peak levels being reached after 8 hours. Thioguanine is extensively metabolized prior to excretion. The elimination half-life is on the order of 80 minutes.

Although 6-thioguanine is chiefly used in chemotherapy for acute myelocytic leukemia and other marrow-based malignancies, lower doses are very effective for moderate to severe psoriasis, particularly in patients who cannot tolerate alternative systemic agents such as methotrexate and cyclosporine.

Dose-related myelosuppression is the major adverse effect produced by 6-thioguanine. Patients deficient in thiopurine methyltransferase (TPMT), a cytosolic enzyme required for metabolism of 6-thioguanine, are at heightened risk. Other adverse effects include gastrointestinal complaints and elevations of liver transaminases. There have been rare reports of more serious hepatotoxicity, including acute hepatitis, acute cholestasis, and hepatic venoocclusive disease.

Poison by ingestion andintraperitoneal routes. Human mutation data reported. Anexperimental teratogen. Other reproductive effects. Ahuman skin irritant. When heated to decomposition itemits very toxic fumes of SOx and NOx.

Thioguanine, 2-aminopurin-6-thiol (30.1.2.12), is made from 2,8-dichloro- 6-hydroxypurine (30.1.2.7), in which the second chlorine atom at C2 is replaced with an amino group when reacted with ammonia, forming 2-amino-8-chloro-6-hydroxy-purine (30.1.2.7), which is then reduced by hydrogen iodide to 2-aminopurin-6-ol (30.1.2.11). Replacement of the hydroxyl group with a mercapto group at C6 is carried out by reacting it with phosphorous pentasulfide, which forms thioguanine (30.1.2.12).

Thioguanine may be useful as adjunctive therapy for acute lymphocytic or granulocytic leukemia in dogs or cats.

Potentially hazardous interactions with other drugs
Antipsychotics: avoid concomitant use with clozapine (increased risk of agranulocytosis).

Tioguanine undergoes extensive metabolism in the liver and other tissues to several active and inactive metabolites. Tioguanine is inactivated mainly by methylation to aminomethylthiopurine; small amounts are deaminated to thioxanthine, and may go on to be oxidised by xanthine oxidase to thiouric acid, but inactivation is essentially independent of xanthine oxidase and is not affected by inhibition of the enzyme. 24-46
% of the dose is excreted in the urine within 24 hours. It is excreted in the urine almost entirely as metabolites

Room temperature

It crystallises from H2O as needles. It has UV at 258 and 347nm (H2O, pH 1) and 242, 270 and 322nm max (H2O, pH 11). [Elion & Hitchings J Am Chem Soc 77 1676 1955, Fox et al. J Am Chem Soc 80 1669 1958.] It is an antineoplastic agent [Kataoka et al. Cancer Res 44 519 1984]. [Beilstein 26 III/IV 3926.]

1) Wang and Wang (2009), 6-thioguanine perturbs cytosine methylation at the CpG dinucleotide site by DNA methyltransferases in vitro and acts as a DNA demethylating agent in vivo; Biochemistry, 48 2290 2) Yuan et al. (2011), 6-thioguanine reactivates epigenetically silenced genes in acute lymphoblastic leukemia cells by facilitating proteasome-mediated degradation of DNMT1; Cancer Res., 71 1904 3) Bohon and de los Santos (2005), Effect of 6-thioguanine on the stability of duplex DNA; Nucleic Acid Res., 33 2880 4) Issaeva et al. (2010), 6-thioguanine selectively kills BRCA2-defective tumors and overcomes PARP inhibitor resistance; Cancer Res., 70 6268