title: Antimicrobial mechanism and activity of dodecyl rosmarinate against Staphylococcus carnosus LTH1502 as influenced by addition of salt and change in pH.
abstract: Antimicrobial activity and mechanism of action of rosmarinic acid (RA) and dodecyl rosmarinate (RE12) against Staphylococcus carnosus LTH1502 were studied as a function of pH (5.8 to 7.2) and in the presence of salts (KCl and MgCl2, 0 to 500 mM). Microbial cultures were exposed to unesterified RA and to esterified RE12, and cell number was determined by plate counting. Cells exposed to RA and RE12 at the minimum bactericidal concentration (200 and 0.05 mM, respectively) were examined using scanning electron microscopy to observe potential morphological changes. Activity of RA was found to be strongly dependent on pH, salt type, and concentration, whereas RE12 led to the compound's activity becoming independent of pH, salt concentration, and type. Scanning electron microscopy images showed that morphology of cells treated with RE12 after incubation of 1 h was irrevocably altered. Our results suggest that esterification (i) altered the mechanism of action by increasing the compound's affinity for cell membranes and (ii) decreased the compound's susceptibility to changes in environmental conditions that alter its charge. Highly specific changes in structure-activity relationships can be observed when esterifying a naturally active phenol such as RA with an alkyl chain that has a carbon chain length of 12.
authors.affiliation: Department of Food Physics and Meat Science, Institute of Food Science and Biotechnology, University of Hohenheim, Garbenstrasse 21/25, 70599 Stuttgart, Germany.
authors.forename: Sarisa
authors.initials: S
authors.lastname: Suriyarak
authors.affiliation: Department of Food Physics and Meat Science, Institute of Food Science and Biotechnology, University of Hohenheim, Garbenstrasse 21/25, 70599 Stuttgart, Germany.
authors.forename: Monika
authors.initials: M
authors.lastname: Gibis
authors.affiliation: Centre de Coopération Internationale en Recherche Agronomique pour le Développement (CIRAD), Unité Mixte de Recherche (UMR), Ingénierie des Agropolymères et Technologies Émergentes (IATE), Montpellier, 34060 France.
authors.forename: Herbert
authors.initials: H
authors.lastname: Schmidt
authors.affiliation: Department of Food Microbiology, Institute of Food Science and Biotechnology, University of Hohenheim, Garbenstrasse 28, 70599 Stuttgart, Germany.
authors.forename: Pierre
authors.initials: P
authors.lastname: Villeneuve
authors.affiliation: Department of Food Physics and Meat Science, Institute of Food Science and Biotechnology, University of Hohenheim, Garbenstrasse 21/25, 70599 Stuttgart, Germany. j.weiss@uni-hohenheim.de.
authors.forename: Jochen
authors.initials: J
authors.lastname: Weiss
mesh_terms: D002934:Cinnamates / Q000494:pharmacology*; D015169:Colony Count, Microbial; D053630:Depsides / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D005516:Food Microbiology; D006863:Hydrogen-Ion Concentration; D008826:Microbial Sensitivity Tests; D008855:Microscopy, Electron, Scanning; D012965:Sodium Chloride / Q000494:pharmacology*; D013210:Staphylococcus / Q000187:drug effects* / Q000648:ultrastructure; D000097123:Rosmarinic Acid
chemical_list: D002934:Cinnamates; D053630:Depsides; D012965:Sodium Chloride; D000097123:Rosmarinic Acid