TDZD-8 is a non-ATP competitive selective inhibitor of the serine/threonine kinase glycogen synthase kinase 3β (GSK3β; IC50 = 2µM), binding to the active site of GSK3β. It does not significantly affect the activities of Cdk-1/cyclin B, CK-II, cAMP-dependent protein kinase or protein kinase C (IC50s = >100 µM), but inhibits PKC and Flt-3 activities (IC50 = 1.4-5.5µM and 673nM, respectively). TDZD-8 has been used to study the role of GSK3β during stem cell differentiation as well as in cell and animal models of Alzheimer’s disease and other neurodegenerative disorders. TDZD-8 is a potent anti-proliferative and pro-apoptotic agent of glioma cells in vitro and in vivo. These effects are associated with an early activation of extracellular signal-regulated kinase (ERK), which is followed by an increased expression of the early growth response-1 (EGR-1) and p21. TDZD-8 potentially inhibits the 33.8-kDa Main protease (Mpro)/3C-like protease of SARS-CoV-2, consequently inhibiting viral transcription and replication and possibly inhibiting spread of COVID-19.