Synthesis and biological properties of benzimidazole-2-selenone compounds with cyclopentyl function

Cancer and antimicrobial resistance continue to pose significant global health challenges. Recently, there has been an increasing interest in N-heterocyclic carbene (NHC) complexes, primarily because of their established catalytic, antibacterial, and antioxidant capabilities. Owing to their low toxicity and high potential for biological activity, NHC compounds have gained considerable attention in cancer research. Selenium supports the immune system by participating within the composition of essential enzymes like glutathione and thioredoxin reductases. Given its role as a biologically active trace element, the biological activity of Se-NHC compounds has also attracted significant interest. This study involved the synthesis of novel Se-NHC compounds and the examination of their antibacterial and anticancer properties. A series of new carbene precursors (2a–2j) were synthesized using benzimidazole derivatives bearing cyclopentyl groups and alkyl substituents with varying steric and functional properties attached to the nitrogen atom. The corresponding Se-NHC compounds (3a–3j) were then obtained by reacting these benzimidazolium salts with selenium. The structures of all synthesized compounds were characterized using 1H NMR, 13C NMR, FT-IR, and HR-MS techniques. The antifungal activities of the compounds were evaluated against Candida albicans and Candida glabrata using the disk diffusion method, while their antibacterial activities were tested against Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli. Furthermore, the anticancer activities of the compounds were assessed using the MTT assay on several cell lines, including BEAS-2B (normal human lung cells), SH-SY5Y (human neuroblastoma), HCT-116 (human colon cancer), MCF-7 (human breast cancer), and A549 (human lung cancer), and their IC50 values were calculated.