1-Azakenpaullone (azakenpaullone) is a potent and selective GSK-3β inhibitor with IC50 of 18 nM, >100-fold selectivity over CDK1/cyclin B and CDK5/p25.

GSK-3β:18 nM

1-Azakenpaullone inhibits the CDK1/cyclin B, CDK5/p25, and GSK-3β effectively, with IC50 of 0.018 μM, 4.2 μM, and 2.0 μM, respectively. [1] In human islets, 1-Azakenpaullone (5 mM) in combination with glucose (8 mM) stimulates the β-cell proliferation. [2] 1-Azakenpaullone effectively stimulates INS-1E cells replication and protects INS-1E cells against glucolipotoxicity-induced cell death. [3][4]

Pretreatment with 1-Azakenpaullone (10 or 100 pmol, i.c.v.) attenuates the ketamine-induced locomotor hyperactivity, disruption of PPI and cognitive de?cits, and improves the ketamine-induced motor incoordination in rotarod test. [5]

Kinase preparations and assays: GSK-3β is assayed, following a 1/100 dilution in 1 mg BSA per mL 10 mM dithiothreitol, with 5 μL 40 μM GS-1 peptide as a substrate, in buffer A, in the presence of 15 μM [γ-32P]ATP (3000 Ci·mmol-1; 1 mCi·mL-1 ) in a final volume of 30 μL. After 30 min incubation at 30℃, 25 μL aliquots of supernatant are spotted onto 2.5×3 cm pieces of Whatman P81 phosphocellulose paper, and 20 s later, the filters are washed five times in a solution of 10 mL phosphoric acid per L of water. The wet filters are counted in the presence of 1 mL ACS scintillation fluid. The kinase activity of CDK1/cyclin B is assayed in buffer C, with 1 mg/mL histone H1, in the presence of 15 μM [γ-32P]ATP (3000 Ci·mmol-1; 1 mCi·mL-1 ) in a final volume of 30 μL. After 10 min incubation at 30℃, 25 μL aliquots of supernatant are spotted onto P81 phosphocellulose papers and treated as described above. The activity of CDK5/p25 is assayed in buffer C as described for CDK1/cyclin B. (Buffer A: 10 mM MgCl2 , 1 mM EGTA, 1 mM dithiothreitol, 25 mM Tris/HCl pH 7.5, 50 μg heparin/mL. Buffer C: homogenization buffer but 5 mM EGTA, no NaF and no protease inhibitors.)

Cell replication is determined by BrdUrd incorporation after treatment with 1-Azakenpaullone for 24 h. The relative cell number is determined after treatment with 1-Azakenpaullone for 4 days using the CyQuant cell proliferation assay. Results are presented as fold change relative to control. (Only for Reference)