Abstract: A variety of terpenoids of plant origin such as anisatin, picrotoxinin and picrodendrins were shown to be noncompetitive antagonists of GABA_A receptors. The results show the selectivity toward the insect receptor and thus represent new leads toward selective insecticides. Two pharmacophore models of rat and housefly′s GABA_A receptors for terpenoids inhibitors were studied by DISCOtech methodology. Two pharmacophore models were verified by the study of the threedimensional quantitative structure and activity relationships, which gave two predictive CoMFA models with q²_rat=0.713 and q²_fly=0.738. According to these results, it was found that negatively charged particle of inhibitor contributed strongly to binding at the rat receptor but showed almost no contribution to the housefly receptor. So these findings will lay a foundation of finding leading compounds and give some guidance on synthesizing insecticides with selectivity activity.

Key words: Inhibitors of terpenoids, Insecticide, Pharmacophore model, GABA_A receptor, Comparative molecular field analysis