丁香油酚和乙酸香茅酯对蜂王信息素活性的影响:量子化学研究

Effects of plant volatile compounds on honeybee queen pheromone: A quantum chemistry study

植物次生代谢物质可影响昆虫信息素的功能,但有关影响机制尚不清楚。本文利用量子化学理论分析了广泛存在于花粉或花蜜中的挥发性丁香油酚和乙酸香茅酯能否与蜜蜂蜂王信息素挥发性成分4-羟基-3-甲氧苯乙醇(HVA)反应。使用Gaussian 09软件来完成几何优化、过渡态搜索、频率分析,并计算了反应能垒和速率常数。结果表明,丁香油酚和HVA分别与OH自由基反应生成有机自由基后,通过自由基-自由基途径发生聚合反应(反应能垒为0.613077 kcal/mol,反应速率常数为9.559953×1011cm3/molecule/s),而不易通过自由基-分子途径发生反应(反应能垒为31.792769 kcal/mol,反应速率常数为4.268854×10-13cm3/molecule/s)。相似地,乙酸香茅酯和HVA分别与OH自由基反应后,也可通过自由基-自由基途径发生反应(反应能垒为2.086469 kcal/mol,反应速率常数为2.328216×1011cm3/molecule/s),但不易通过自由基-分子途径发生反应(反应能垒为25.881002 kcal/mol,反应速率常数为1.513828×10-8cm3/molecule/s)。由于全球环境变化可能导致大气中OH自由基浓度升高,使得花蜜或花粉中挥发性不饱和化合物有可能影响蜂王信息素的功能,从而干扰蜂群的化学通讯。

Plant secondary compounds are able to affect the activities of some insect pheromones,but the underlying mechanisms remain unclear. In this study,we use quantum chemistry theory to assay whether the two plant volatiles,engenol and citronellyl acetate that are ubiquitous in floral nectar and pollen,react with homovanillyl alcohol（ HVA）,a volatile component of the Apis mellifera bee queen pheromone.Geometry optimization,transition state searching and frequency calculations by Gaussian 09 show that engenol and HVA can readily react with OH,respectively. The two reaction intermediates can induce a polymerization reaction through the radical-radical pathway（ the energy barrier and rate constant for the pathway are 0. 613077 kcal / mol and 9. 559953 × 10^11cm3/ molecule / s, respectively）, but unlikely through the radical-molecule pathway（ the energy barrier and rate constant for the pathway are31. 792769 kcal / mol and 4. 268854 × 10^（-13）cm3/ molecule / s,respectively）. Similarly,after citronellyl acetate and HVA react with OH,respectively,their reaction productions would polymerize through radicalradical pathway（ the energy barrier and rate constant for the pathway are 2. 086469 kcal / mol are and2. 328216 × 10^11cm3/ molecule / s,respectively）,but unlikely through the radical-molecule pathway（ theenergy barrier and rate constant for the pathway are 25. 881002 kcal / mol and 1. 513828 × 10^（-8）cm3/ molecule / s,respectively）. Our study suggests that abundant OH radical due to climate change may make honeybee queen pheromone less resistant against plant volatiles, thereby disturbing chemical communication in honeybees.