Pesticide Toxicology Laboratory, Department of Entomology, Iowa State University, Ames, IA, USA.
Pest Manag Sci. 2012 Aug;68(8):1122-9. doi: 10.1002/ps.3280. Epub 2012 Mar 28.
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.
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.
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.
单萜类化合物是一大类植物次生代谢物。许多这些天然存在的化合物在害虫昆虫上显示出良好的杀虫效力。本实验室的先前研究表明，一些单萜类化合物对昆虫 GABA 受体具有正调节作用。在这项研究中，通过开发定量构效关系 (QSAR) 模型，确定了参与家蝇 GABA 受体中单萜结合活性的单萜类化合物的关键性质，并评估了这些单萜类化合物的毒性与其 GABA 受体结合活性之间的关系。
确定了对 [³H]-TBOB 结合具有显著影响的 9 种单萜类化合物和至少有一个氧原子连接到环上的 9 种 p-薄荷烷类似物的两个 QSAR 模型。在这两个 QSAR 模型中，某些碳原子上的 Mulliken 电荷、log P 值和总能量与对家蝇 GABA 受体的结合活性显示出显著关系。
从 QSAR 模型中，可以看出一些化学和结构参数，包括单萜类分子的电子性质、疏水性和稳定性，强烈参与与家蝇 GABA 受体的结合活性。这些发现将有助于了解这些天然杀虫剂的作用模式，并为预测更多的单萜类杀虫剂提供指导。
