Synthesis and Evaluation of Antimicrobial Properties of Some Chalcones

Abstract

Introduction: Recently there has been a great deal of interest in the health benefits of phytochemicals, particularly prenylated and allylated flavonoids. Chalcones (1, 3-diaryl-2-propen-1-ones) and their derivatives are important intermediates of the flavonoid synthetic pathway. Aims: To synthesis chalcones, and investigate their antimicrobial properties by determining their diameters of inhibition; minimum inhibitory concentration (MIC); and their minimum bactericidal and fungicidal concentrations (MBC), using the Kirby-Bauer diffusion and microdilution method. Study Design: Experimental analytical study. Place and Duration of Study: The study was done in the Laboratory of Organic Chemistry of the Faculty of Science, University of Yaounde1 and the Bacteriology Laboratory of the Yaoundé University Teaching Hospital. The study was done in a period of 6 months, from the 15th of December 2014 to the 22nd of May 2015. Methodology: The chalcones (3a-c) were synthesized by the Claisen Schmidt condensation reaction of vanillin (1) with different acetophenone derivatives (2a-c). Results: The structures of the compounds were confirmed by spectral data (1H and 13C Nuclear Magnetic Resonance). Compound 3c is a new compound while the compounds 3a and 3b have already been reported [26,27]. The synthesized compounds were tested for their antimicrobial activities (agar disc-diffusion and microdilution methods). All the synthesized chalcones were active against the test microbes: The most potent compound was 3c; bactericidal on 50% of strains with a MIC between 62.5 and 250 μg/mL, the most sensitive strains being S. aureus and C. albicans, and the least sensitive being E. faecalis. Conclusion: Synthesized chalcones showed antimicrobial properties and are very promising as lead compounds for drug development. We demonstrated that all the test microbes were susceptible to the 3 synthesized chalcones at low concentrations. The halogenated chalcone (3c) was the most potent of the synthesized chalcones against reference strains of Gram negative and Gram positive bacteria, and the clinical strain of C. albicans. Therefore the presence of halogens in chalcones increases their microbial susceptibility.