This paper presents the synthesis and characterization of new thiosemicarbazone derivatives with potential applications as antibacterial, antioxidant and anticancer agents. Six thiosemicarbazone derivatives (L–L5) were synthesized by reacting an appropriate thiosemicarbazide derivative with 2-pyridinecarboxaldehyde. The structures of the obtained compounds were confirmed using mass spectrometry, infrared spectroscopy, and NMR spectroscopy. Antibacterial activity was evaluated by using the microdilution method, determining the minimum inhibitory concentration (MIC) against a panel of Gram-positive and Gram-negative bacteria. Compound L1 showed the most potent antibacterial activity, especially against Bacillus cereus (MIC 10 mg/L). Molecular docking to topoisomerase II and transcriptional regulator PrfA suggests that the studied compounds can effectively bind to molecular targets recognized in anticancer and antibacterial therapies. An assessment of physicochemical properties (ADME) indicates favorable parameters of the compounds as potential drugs. Compounds L and L2 showed the highest antioxidant activity, surpassing the activity of the Trolox standard. Cytotoxicity against A549 lung cancer cells was evaluated by the MTT assay. Compound L4 exhibited the strongest inhibitory effect on cancer cell survival. The obtained results indicate that the synthesized thiosemicarbazide derivatives, especially L1, L2, and L4, are promising compounds with potential applications as antibacterial and anticancer drugs.

This study focuses on the multitarget biological evaluation of variously substituted 4-pyridyl thiosemicarbazones. Six compounds (C1-C6) containing chlorine atoms in different positions of the phenyl ring were synthesized, and their structures were confirmed using mass spectrometry, FTIR, and NMR spectroscopy. Biological evaluation included antioxidant activity assays (ABTS, DPPH, and ORAC-FL), antibacterial testing against Gram-positive and Gram-negative bacteria, and anticancer activity assessment against a panel of cancer cell lines (A375, G-361, LNCaP, Caco-2, and U-87 MG), as well as healthy fibroblasts (BJ) to evaluate selectivity. While the compounds exhibited limited antibacterial activity, more pronounced anticancer effects were observed, particularly for a singly chlorinated derivative, with reduced cytotoxicity toward healthy cells. No direct correlation was observed between anticancer and antioxidant activities. Finally, ADME analysis suggested favorable pharmacokinetic profiles for all six compounds.