Tideglusib (NP031112), a non-ATP competitive inhibitor of glycogen synthase kinase 3 (GSK-3), is with anti-inflammatory and neuroprotective activities.

[35S]Tideglusib (207 Bq/nmol) at 55 μM is incubated with 5 μM GSK-3β for 1 h at 25°C in 315 μL of 50 mM Tris-HCl, pH 7.5, containing 150 mM NaCl and 0.1 mM EGTA. The incubation is extended for another 30 min after having added 35 μL of the same buffer with or without 100 mM DTE. Samples are then processed in three different ways. First, an aliquot of 125 μL of each sample is mixed with 375 μL of 8 M GdnHCl in Water and heated at 80°C for 5 min. A second aliquot of 125 μL is diluted up to 500 μL with Water and left at room temperature for 5 min. In both cases, the free drug is removed afterwards by gel filtration through Sephadex G-25, and the amount of bound drug is determined by liquid scintillation counting on a 1450-MicroBeta TriLux counter. Finally, a third 40 μL aliquot of each original sample is mixed with 10 μL of denaturing electrophoresis sample buffer without reducing agents, and 35 μL of this mixture is loaded onto a 10% polyacrylamide gel and subjected to SDS-PAGE (again in the absence of reducing agents except for the DTE already included in the corresponding sample), followed by fluorography of the dried gel[1].