Thiazolyl Benzenesulfonamide Derivative as a Novel Inhibitor of Thymidine Kinase: Promising Therapeutics Against Staphylococcus aureus

The emergence of multidrug-resistant Staphylococcus aureus necessitates novel antimicrobial strategies. This study reports the synthesis and evaluation of thiazolyl benzenesulfonamide-derived synthetic kinase inhibitors targeting thymidine kinase (TK), essential for bacterial DNA metabolism. Derivatives were synthesized via aromatic ring modifications and characterized by ¹H/¹³C NMR. Compound DSA3 exhibited significant interaction with TK. Fluorescence binding assays confirmed high-affinity DSA3–TK binding, corroborated by isothermal titration calorimetry revealing exothermic, spontaneous complex formation (favorable ΔG, ΔH, ΔS). Molecular docking positioned DSA3 within the TK ATP-binding pocket, forming hydrogen bonds and hydrophobic contacts with key residues, including the catalytic residue Glu89. Molecular dynamics simulations indicated DSA3 stabilizes TK structure by inducing minimal conformational perturbation. Crucially, DSA3 potently inhibited the ATPase activity of TK with an IC₅₀ value of 6.99 µM, disrupting its enzymatic function. In vitro antimicrobial testing showed the MIC value of 50 µM, demonstrating the potent activity of DSA3 against S. aureus (ATCC 29213). These integrated findings validate DSA3 as a promising TK inhibitor, effectively impeding bacterial growth by targeting DNA synthesis. This highlights the potential of DSA3 as a novel therapeutic agent against multidrug-resistant S. aureus infections, offering a mechanism to circumvent prevailing resistance.