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United States Department of Agriculture

Agricultural Research Service

Research Project: BITING ARTHROPODS: INTEGRATED PEST MANAGEMENT

Location: Mosquito and Fly Research Unit

Title: Correlation of lipophilicity with mosquito larvicidal and repellent activities of novel trifluoromethylphenyl amides

Authors
item Tsikolia, Maia
item Bernier, Ulrich
item Agramonte, Natasha
item Coy, Monique
item Becnel, James
item Clark, Gary
item Linthicum, Kenneth

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: February 6, 2014
Publication Date: N/A

Technical Abstract: For a chemical to have a biological impact on an organism, the molecules must be capable of being transported across the membranes of cells. Lipophilic insecticides that can pass through lipid bilayers and penetrate the insect cuticle can lead to rapid intoxication or mortality by acting on the nervous system. LogP values are a measurement of a partition between two phases (octanol and water) for an unionized (neutral) compound. This study explores the relationship between lipophilicity (in terms of LogP values), and larvicidal and repellent activity against Aedes Aegypti for a series of similarly structured compounds. For twenty trifluoromethylphenyl amides, the LogP values were calculated and compared to larvicidal and repellency bioassay results. Calculation of LogP was accomplished by using the virtual computational software programs, Molinspiration and ALOGPS 2.1. We observed that compounds with higher LogP (4.0-5.1) values, exibited more potent larvicidal activity; although compounds that exceeded a certain level of lipophilicity (LogP~5.3) had decreased larvicidal activity. We observed an increase in repellent activity with increasing lipophilicity (LogP from ~4 to ~5). However, lipophilicity of the most active repellents within this set had LogP values that ranged from 2.8-4.4. In conclusion, this study indicates that the lipophilicity coefficient may be an important property to consider in the design of insecticide and repellent candidates.

Last Modified: 9/10/2014
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