Selenium-N-heterocyclic carbene (Se-NHC) complexes with higher aromaticity inhibit microbes: synthesis, structure, and biological potential

Abstract

The synthesis of five selenium complexes bearing imidazole-based N-heterocyclic carbene ligands (Se-NHC) are reported. The adducts were characterized by elemental and spectroscopic analysis (FTIR, ¹H and ¹³C NMR). Single-crystal XRD confirmed the structures of two Se-NHC adducts, VIII and XI. Zone of inhibition (ZOI) values of Se-NHC complexes were evaluated towards two bacterial (Bacillus thuringiensis and Escherichia coli) and one fungal strain (Candida albicans). The most active tested compound was XI with inhibition value of 24.1 ± 0.1 mm against E. coli, and it showed higher activity than Tetracycline (reference drug). Similarly, XI exhibited good inhibition potential against C. albicans (26.5 ± 0.2 mm). The hemolytic assay demonstrated that the tested compounds (VIII-XII) are non-toxic to healthy human blood; however, thrombolysis indicated that VIII-XII could be used as potential thrombolytic agents. It is concluded that Se-NHC carbene adducts having more aromatic rings at terminal nitrogens of imidazole are more effective than other tested compounds. Se-NHC compounds have more efficacy against bacterial strains than fungal strain.

Graphical Abstract

Keywords:

• Imidazolium salts
• Se–NHC adducts
• antimicrobial
• antioxidant
• hemolytic
• thrombolysis

Acknowledgements

The authors are thankful to the higher education commission of Pakistan for awarding research grant NRPU-8198. The authors are thankful to the Professor Murray Baker, Honorary Professor, The University of Western Australia (M310), 35 Stirling Highway, 6009 Perth, Australia for his sincere guidance during IRSIP period of first author.

Disclosure statement

The authors declare no conflict of interest.

Additional information

Funding

The authors are thankful to the higher education commission of Pakistan for awarding research grant NRPU-8198. The authors are thankful to the Professor Murray Baker, Honorary Professor, The University of Western Australia (M310), 35 Stirling Highway, 6009 Perth, Australia for his sincere guidance during IRSIP period of first author.