Antioxidant cysteine and methionine derivatives show trachea disruption in insects

To prevent the deterioration of the global environment, the reduction of chemical pesticide use and the development of eco-friendly pest control technologies are urgent issues. Our recent study revealed that the production of reactive oxygen species (ROS) by dual oxidase (Duox) plays a pivotal role in stabilizing the tracheal network by intermediating the tyrosine cross-linking of proteins that constitute trachea. Notably, the formation of dityrosine bonds by ROS can be inhibited by the intake of an antioxidant cysteine derivative N-acetyl-L-cysteine (NAC), which can suppress insect respiration. In this study, we screened for the derivatives showing insecticidal activity and tracheal formation inhibition. As a result of investigating the soybean pest bug Riptortus pedestris, cysteine and methionine derivatives showed respiratory formation inhibition and high insecticidal activity. In particular, NAC had a slow-acting insecticidal effect, while L-cysteine methyl ester (L-CME) showed relatively fast-acting insecticidal activity. Furthermore, the insecticidal activity of these derivatives was also detected in Drosophila, mealworms, cockroaches, termites, and plant bugs. Our results suggest that some antioxidant compounds have specific tracheal inhibitory activity in different insect species and they may be used as novel pest control agents upon further characterization.

为遏制全球环境恶化，减少化学农药使用量、开发生态友好型害虫防治技术已是亟待解决的重大课题。我们的最新研究发现，双氧化酶（dual oxidase, Duox）产生的活性氧（reactive oxygen species, ROS），通过介导构成气管的蛋白质的酪氨酸交联反应，在稳定气管网络中发挥关键作用。值得注意的是，活性氧介导的二酪氨酸键形成可被抗氧化剂半胱氨酸衍生物N-乙酰-L-半胱氨酸（N-acetyl-L-cysteine, NAC）抑制，而该物质可抑制昆虫呼吸作用。本研究针对具备杀虫活性与气管形成抑制活性的衍生物开展筛选。通过对大豆害虫豆缘蝽（Riptortus pedestris）开展实验，结果显示半胱氨酸与甲硫氨酸衍生物可抑制呼吸作用并展现出高杀虫活性。具体而言，NAC表现出迟效性杀虫效果，而L-半胱氨酸甲酯（L-cysteine methyl ester, L-CME）则展现出相对速效的杀虫活性。此外，此类衍生物的杀虫活性在果蝇、黄粉虫、蟑螂、白蚁以及盲蝽类昆虫中均有检出。本研究结果表明，部分抗氧化剂化合物在不同昆虫物种中具备特异性气管抑制活性，经进一步表征后可作为新型害虫防治药剂加以应用。