title: Predictability of ionic liquid toxicity from a SAR study on different systematic levels of pathogenic bacteria.
abstract: Ionic liquids (ILs), a new class of solvents with unique and tunable physicochemical properties, were initially envisioned as working alternatives to traditional organic solvents. However, they have now proven to have a wide range of alternative chemical and biochemical applications. Due to their increasing use, environmental and toxicity concerns are growing, but resolutions are hindered by the sheer number of possible variants. In order to assess and possibly predict IL-toxicity, a structure-activity relationship (SAR) approach was adopted using defined structural motifs. These included varied cationic alkyl side-chain lengths, cation lipophilicity and diverse anion effects. The predictive powers of such SARs in respect of antibacterial effects were compared using a total of 28 ILs on six Gram-negative and six Gram-positive pathogenic bacteria. Endpoints were minimum inhibitory (MIC) and minimum bactericidal concentrations (MBC). Results indicate that while certain limited IL-toxicity responses in bacteria can be predicted from SARs, they caution that predictions cannot be generalized across species. This study demonstrates the complex species-specific nature of IL-toxicity and the current limitations of SAR predictability.
authors.affiliation: Merck KGaA, Life Science, Frankfurter Str. 250, 64293 Darmstadt, Germany.
authors.forename: Nadine
authors.initials: N
authors.lastname: Weyhing-Zerrer
authors.affiliation: Christian Doppler Laboratory for Monitoring of Microbial Contaminants, Department of Veterinary Public Health and Food Science, University of Veterinary Medicine, Veterinaerplatz 1, 1210 Vienna, Austria.
authors.forename: Tobias
authors.initials: T
authors.lastname: Gundolf
authors.affiliation: Proionic GmbH, Parkring 18, 8074 Grambach, Austria.
authors.forename: Roland
authors.initials: R
authors.lastname: Kalb
authors.affiliation: Merck KGaA, Life Science, Frankfurter Str. 250, 64293 Darmstadt, Germany.
authors.forename: Rolf
authors.initials: R
authors.lastname: Oßmer
authors.affiliation: Christian Doppler Laboratory for Monitoring of Microbial Contaminants, Department of Veterinary Public Health and Food Science, University of Veterinary Medicine, Veterinaerplatz 1, 1210 Vienna, Austria; Institute of Milk Hygiene, Milk Technology and Food Science, Department of Veterinary Public Health and Food Science, University of Veterinary Medicine, Veterinaerplatz 1, 1210 Vienna, Austria.
authors.forename: Peter
authors.initials: P
authors.lastname: Rossmanith
authors.affiliation: Christian Doppler Laboratory for Monitoring of Microbial Contaminants, Department of Veterinary Public Health and Food Science, University of Veterinary Medicine, Veterinaerplatz 1, 1210 Vienna, Austria. Electronic address: patrick-julian.mester@vetmeduni.ac.at.
authors.forename: Patrick
authors.initials: P
authors.lastname: Mester
mesh_terms: D000838:Anions / Q000737:chemistry / Q000633:toxicity; D002412:Cations / Q000737:chemistry / Q000633:toxicity; D006090:Gram-Negative Bacteria; D006094:Gram-Positive Bacteria; D052578:Ionic Liquids / Q000737:chemistry* / Q000633:toxicity*; D008826:Microbial Sensitivity Tests; D015394:Molecular Structure; D011237:Predictive Value of Tests; D013329:Structure-Activity Relationship
chemical_list: D000838:Anions; D002412:Cations; D052578:Ionic Liquids
keywords: Antimicrobial activity; Bacteria; Ionic liquids; SAR; Toxicity