title: Quantitative structure-activity relationships of monoterpenoid binding activities to the housefly GABA receptor.
abstract: BACKGROUND
  Monoterpenoids are a large group of plant secondary metabolites. Many of these naturally occurring compounds have shown good insecticidal potency on pest insects. Previous studies in this laboratory have indicated that some monoterpenoids have positive modulatory effects on insect GABA receptors. In this study, the key properties of monoterpenoids involved in monoterpenoid binding activity at the housefly GABA receptor were determined by developing quantitative structure-activity relationship (QSAR) models, and the relationship between the toxicities of these monoterpenoids and their GABA receptor binding activities was evaluated.
  
  
  RESULTS
  Two QSAR models were determined for nine monoterpenoids showing significant effects on [³H]-TBOB binding and for nine p-menthane analogs with at least one oxygen atom attached to the ring. The Mulliken charges on certain carbon atoms, the log P value and the total energy showed significant relationships with binding activities to the housefly GABA receptor in these two QSAR models.
  
  
  CONCLUSIONS
  From the QSAR models, some chemical and structural parameters, including the electronic properties, hydrophobicity and stability of monoterpenoid molecules, were suggested to be strongly involved in binding activities to the housefly GABA receptor. These findings will help to understand the mode of action of these natural insecticides, and provide guidance to predict more monoterpenoid insecticides.
authors.affiliation: Pesticide Toxicology Laboratory, Department of Entomology, Iowa State University, Ames, IA, USA.
authors.forename: Fan
authors.initials: F
authors.lastname: Tong
authors.forename: Joel R
authors.initials: JR
authors.lastname: Coats
mesh_terms: D000818:Animals; D006793:Houseflies / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D019476:Insect Proteins / Q000737:chemistry / Q000378:metabolism*; D007306:Insecticides / Q000737:chemistry* / Q000494:pharmacology*; D015394:Molecular Structure; D039821:Monoterpenes / Q000737:chemistry* / Q000494:pharmacology*; D011485:Protein Binding; D021281:Quantitative Structure-Activity Relationship; D018079:Receptors, GABA / Q000737:chemistry / Q000378:metabolism*
chemical_list: D019476:Insect Proteins; D007306:Insecticides; D039821:Monoterpenes; D018079:Receptors, GABA