Synthesis and Anti‐Listeria Properties of Odorless Hybrid Bio‐Based n‐Phenolic Vegetable Branched‐Chain Fatty Acids

Consumers are becoming concerned about the impact of synthetic chemicals on human health and environments, and demanding natural compounds to reduce risk of antibiotic resistance of microorganisms. However, natural compounds are often less effective than synthetic antimicrobials. This challenge may be addressed with the development of bio-based antimicrobial agents. In this study, bio-based n-phenolic branched-chain fatty acids (n-phenolic-branched chain fatty acid [BCFA]) were synthesized from vegetable oil (soybean and safflower) fatty acids and four natural phenolics (phenol, thymol, carvacrol, and creosote), and tested against Listeria innocua. Results revealed that the newly synthesized products in crude form had minimum inhibitory concentrations (MIC) against L. innocua ranging from 3.6 to 116.4 mu g mL(-1), with phenol-BCFA products having the lowest MIC (3.6 mu g mL(-1)) and minimum bactericidal concentration (MBC) (7.3 mu g mL(-1)). The precursors (unsaturated free fatty acids and phenolics) and noncovalently bound mixture of free fatty acids and phenolics had MIC above 232.7 mu g mL(-1). After purification by molecular fractionation, n-phenolic-BCFA in the free fatty acid/monomer form were shown to be responsible for the anti-Listeria activity with MIC of 3.6-7.3 mu g mL(-1) and MBC of 7.3-29.1 mu g mL(-1). These promising results pave the road for further study of this new class of bio-based compounds, which may lead to their widespread use.