title: Inactivation of Gram-Positive Bacteria by Novel Phenolic Branched-Chain Fatty Acids.
abstract: Novel phenolic branched-chain fatty acids (PBC-FAs) were evaluated for their antimicrobial properties against both gram-positive ( Listeria innocua , Bacillus subtilis , Enterococcus faecium ) and gram-negative ( Escherichia coli , Salmonella Typhimurium, and Pseudomonas tolaasii ) bacteria. In addition, PBC-FA derivatives, such as PBC-FA methyl ester mixture, methyl-branched fatty acid mixtures, and trimethylsilyl-PBC-FA methyl esters, were synthesized to study the structure activity relationship. Results showed that PBC-FAs were a potent antimicrobial against gram-positive bacteria with MICs of 1.8 to 3.6 μg/ml. The compounds were less effective against gram-negative bacteria. Derivatives of PBC-FAs and an equimolar mixture of oleic acid and phenol all had MICs above 233 μg/ml against both gram-positive and gram-negative bacteria. Comparison of antimicrobial activities of the PBC-FAs with those of the derivatives suggests that the carboxylic group in the fatty acid moiety and the hydroxyl group on the phenol moiety were responsible for the antimicrobial efficacy. Growth curves of L. innocua revealed that PBC-FAs prevented bacterial growth, while MBC-FAs only delayed the onset of rapid growth of L. innocua . Our results demonstrated that the novel PBC-FAs have potential for use as antimicrobials against gram-positive bacteria.
authors.affiliation: U.S. Department of Agriculture, Agricultural Research Service, Eastern Regional Research Center, 600 East Mermaid Lane, Wyndmoor, Pennsylvania 19038, USA.
authors.forename: Xuetong
authors.initials: X
authors.lastname: Fan
authors.affiliation: U.S. Department of Agriculture, Agricultural Research Service, Eastern Regional Research Center, 600 East Mermaid Lane, Wyndmoor, Pennsylvania 19038, USA.
authors.forename: Karen
authors.initials: K
authors.lastname: Wagner
authors.affiliation: U.S. Department of Agriculture, Agricultural Research Service, Eastern Regional Research Center, 600 East Mermaid Lane, Wyndmoor, Pennsylvania 19038, USA.
authors.forename: Kimberly J B
authors.initials: KJ
authors.lastname: Sokorai
authors.affiliation: U.S. Department of Agriculture, Agricultural Research Service, Eastern Regional Research Center, 600 East Mermaid Lane, Wyndmoor, Pennsylvania 19038, USA.
authors.forename: Helen
authors.initials: H
authors.lastname: Ngo
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry*; D005227:Fatty Acids; D006090:Gram-Negative Bacteria; D006094:Gram-Positive Bacteria; D008826:Microbial Sensitivity Tests; D010636:Phenols
chemical_list: D000900:Anti-Bacterial Agents; D005227:Fatty Acids; D010636:Phenols
keywords: Antimicrobial; Bacteria; Fatty acid; Phenolic branched-chain fatty acids