Evaluation of the antimicrobial and antioxidant properties of synthetic phenolipids

Functionalization of phenolic compounds by lipophilization allowing the synthesis of new compounds with improved biological properties. This study aims to investigate the antimicrobial effects of eight synthesized phenolipids, derived from bioactive coumaric and ferulic acid esters, against Bacillus subtilis, Escherichia coli, and Candida albicans. Antioxidant activity, as well as antimicrobial capacity were evaluated through DPPH assays and classical disc agar diffusion, respectively, concomitantly with the evaluation of cellular viability using flow cytometry assay. Antioxidant activities results showed that ferulic acid esters exhibit higher antiradical activity than coumaric acid esters. Results of agar diffusion assay revealed that, 1-methylpropyl coumarate and 1-methylpropyl ferulate (1-MPF) have an effective antimicrobial activity with Minimum Inhibitory Concentrations (MICs) values between 0.9 – 3.5mM against all tested microorganisms. Also, flow cytometry showed that 1-MPF and decyl coumarate exhibited significant bactericidal activity (p < 0.05), with almost 63% of dead Bacillus subtilis cells. Compared to the commonly used agar method, flow cytometry proved to be a fast and straightforward analytical tool to assess antimicrobial activity while providing information on inhibition type. These results suggest the applicability of phenolipids as potent lipophilic bioactive molecules to protect food products and cosmetic formulations from oxidative stress and microbial spoilage.