Submitted to: Pesticide Management Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/23/2005
Publication Date: 12/1/2005
Citation: Natarajan, R., Basak, S., Balaban, A., Klun, J.A., Schmidt, W.F. 2005. Chirality index, molecurlar overlay and the activity of stereoisomeric topical mosquito repellents. Pesticide Management Science. 61:1193-1201. Interpretive Summary: Many dangerous diseases, such as West Nile Virus, Lyme Disease and Malaria are transmitted by insects and other arthropods. Insect repellents are the first line of protection for individuals, and new and more effective repellents are always needed. One method to develop new repellents is to study the chemistry of the chemical compounds in repellents that are known to be effective, learn why they are effective, and design new compounds with those characteristics. We studied three widely used repellent compounds. Our results provided important information about what makes those compounds effective arthropod repellents. The new three-dimensional chemical structural information will be used by synthetic organic chemists to design new and more effective arthropod repellents for protection of humans.
Technical Abstract: Bayrepel, 2-(2-hydroxyethyl)-1-piperidine carboxylic acid-1-methylpropyl ester, and 220, 1-(cyclohex-3-ene-1-ylcarbonyl)-2-methylpiperidine have two chiral centers, and each of the four isomers has repellent activity. The degree of mosquito repellency of these stereoisomers individually and as racemic pairs has been quantified by the United States Department of Agriculture. Computational chemistry was used to identify the structural and configurational basis for repellent activity. Molecular overlay of the optimized geometries of the lowest energy conformers of the configurational isomers was investigated as a method to elucidate the role of chiral centers in 220 and Bayrepel. It was found that the presence of a chiral carbon alpha to the nitrogen with the S-configuration in the piperidine ring is essential to the three-dimensional arrangement of the atoms of the pharmacophore for effective repellent activity.