Thioguanine

Thioguanine (CAS No. 154-42-7) is a thiopurine immunosuppressant with antitumor and antiviral properties. Its therapeutic targets include hypoxanthine-guanine phosphoribosyltransferase (HGPRT) and DNA methyltransferase 1 (DNMT1). Its IC₅₀ values cover multiple scenarios: 0.9302 μM against EV71 virus (in HT-29 cells, selectivity index [SI] > 2150.1), 5.481~23.09 μM for antitumor activity (in MCF-7 breast cancer cells), 3.92~5.81 μM in PA-1 ovarian cancer cells, and a LC₅₀ of 5.0 μg/ml in leukemia cells (T-cell acute lymphoblastic leukemia [T-cell ALL]). Clinically, it is primarily indicated for patients with inflammatory bowel disease (IBD) who are intolerant to or unresponsive to azathioprine (AZA)/mercaptopurine (MP). The recommended oral initial and maintenance dose is 20 mg per day, which can be adjusted to 10~80 mg per day based on tolerability. Low doses (≤20 mg per day) are associated with a low risk of hepatotoxicity. In in vitro experiments, the effective antiviral concentration ranges from 0.5 to 3 μM, and the effective antitumor concentration ranges from 3.92 to 23.09 μM.

References:

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