Mechanistic insights into the inhibition of microtubule affinity-regulating kinase 4 by Syringic acid: A computational and experimental study

Microtubule affinity regulating kinase 4 (MARK4) is a vital protein kinase that serves as a dual target in cancer and neurodegenerative diseases. It is implicated in the development of tauopathies and also linked to the pathogenesis of several cancer types, implying its importance. Syringic acid is a naturally occurring phenolic molecule that has shown significant efficacies in cancer and neurodegenerative diseases by modulating several key pathways. Thus, the present study aims to investigate the inhibitory potential of syringic acid against the protein kinase MARK4, employing a combination of experimental and computational approaches. Molecular docking revealed the binding of syringic acid in the MARK4's binding pocket, interacting with key functional residues of the protein kinase. Molecular dynamic simulation (MD) studies demonstrated the conformational dynamics and structural stability of MARK4 upon the binding of syringic acid. In silico findings were further complemented by experimental assays. Enzyme inhibition assay showed that syringic acid effectively inhibits MARK4 with an IC₅₀ value of 4.32 μM. Fluorescence binding assays revealed a strong binding affinity (K = 2.8 × 10⁶ M⁻¹). The findings of our study establish syringic acid as a potent MARK4 inhibitor, providing a perfect platform for its use in tackling MARK4-associated diseases.