Hydrophobic Derivatives of Glycopeptide Antibiotics as Inhibitors of Protein Kinases

As key regulators of cell signaling, protein kinases (PKs) are attractive targets for therapeutic intervention in a variety of diseases. Herein, we report for the first time the inhibitory activity of polycyclic peptides, particularly, derivatives of glycopeptide antibiotics teicoplanin and eremomycin, against a panel of 12 recombinant human protein kinases and two protein kinases (CK1 and CK2) isolated from rat liver. Several of the investigated compounds inhibited various PKs with IC₅₀ values below 10 μM and caused >90% suppression of the enzyme activity at 10 µM concentration. Kinetic analysis of the protein kinase CK2α inhibition by the teicoplanin aglycon analogue (7) demonstrated the non-competitive mechanism of inhibition (with regard to ATP). Interestingly, the inhibitory activity of some investigated compounds correlated with the earlier described antiviral activity against HIV, HCV, and other corona- and flaviviruses.