Discovery of triterpenoid derivatives as novel selective CDC2-like kinase 2 inhibitors against knee osteoarthritis

CDC2-like kinase 2 is a promising target for the therapy of knee osteoarthritis. A series of natural and commercial triterpenoid derivatives were evaluated for their inhibitory activity against CDC2-like kinase 2 using ADP-Glo assay by GloMax ® Navigator Microplate Luminometer. Most of these triterpenoid derivatives exhibited the moderate inhibitory activity against CDC2-like kinase 2, but in particular, Methyl ganoderate A showed the highest inhibitory activity with an IC 50 value of 0.69 μM against CDC2-like kinase 2. Methyl ganoderate A showed the inhibitory activity against CLK1, CLK2, CLK3, CLK4, DYRK1A, and DYRK2 with IC 50 values of 8.79 μM, 0.69 μM, >20 μM, 10.75 μM, 9.06 μM, and >20 μM, indicating that it is a novel and selective CDC2-like kinase 2 inhibitor. Preliminary structure–activity relationships (SARs), molecular docking, and molecular dynamics simulation of Methyl ganoderate A against CDC2-like kinase 2 were studied. The investigation of mechanisms indicated that Methyl ganoderate A inhibited cartilage degradation and exerted anti-inflammatory effects in vitro.