Design, synthesis, and primary activity assays of baicalein derivatives as cyclin-dependent kinase 1 inhibitors

Malignant tumor is a disease with high mortality. Traditional treatment methods have many disadvantages, such as side-effects, drug resistance. Because cyclin-dependent kinase 1 (CDK1) plays an indispensable role in cell cycle regulation, it became an attractive target in rational anti-cancer drug discovery. Herein, we reported a series of baicalein derivatives, which remarkably repressed the proliferation of MCF-7 tumor cells and the activity of CDK1/cyclin B kinase. Among them, compound 4a displayed better inhibition rate than flavopiridol against MCF-7 proliferation at the concentration of 50 μg/ml, comparable to compound CGP74514A, while compound 3o possessed the best activity against CDK1/cyclin B kinase (IC₅₀  = 1.26 μM). The inhibitory activities toward the kinase well correlated with anti-proliferative activities. Molecular docking results suggested that compound 3o can interact with the key amino acid residues, E81, L83, and D146, of CDK1 through hydrogen bond just like flavopiridol does. And it can also form an extra hydrogen bond with D146 by its introduced 7-acrylate group, which flavopiridol does not have. These findings proved that baicalein derivatives can be used as CDK1 inhibitors fighting against cancer.