Microwave-assisted synthesis of bioactive pyridine-functionalized N-alkyl-substituted (benz)imidazolium salts

Imidazolium salts have always been well recognized as the precursors to ionic liquids. Various studies have been extended to their biological properties, in which many have discovered interesting results. In this study, a series of pyridine-functionalized (benz)imidazolium salts were synthesized using the conventional synthetic method, and microwave irradiation. The products were tested biologically against a list of microorganisms via broth microdilution assay and cancer cell lines using a standard MTT assay. Lead compound 4 e exhibited great antimicrobial properties with lowest MIC value of 3.91 μg/mL against Bacillus cereus, Bacillus subtilis, Staphylococcus aureus and Enterococcus faecalis. Remarkable anticancer properties of 3 f were shown with IC₅₀ value as low as 0.71 μM against human colon cancer (HCT116). From our study, the MIC of 4 e and IC₅₀ values of 3 f surpassed the potency of positive controls such as chloramphenicol (8.08–16.2 μg/mL) and cisplatin (10.78 μM) respectively. Additionally, the use of microwave irradiation has significantly reduced the reaction time from 5 days in a conventional setup, to a 3-hour synthetic reaction in a microwave synthesizer.