Design, Synthesis, and Aphicidal Activity of Novel Insect Neuropeptide Kinin Receptor Antagonists, Targeting the Ser² Ligand Position

Traditional chemical pesticides have raised significant environmental and health concerns, driving the pursuit of safer alternatives. Aphids, notorious for causing extensive agricultural damage and transmitting plant diseases, represent prime targets for next-generation insecticide development. This study investigates kinin neuropeptides, which regulate key physiological processes, as novel targets for biopesticide design. Using the kinin peptide as a structural lead, we synthesized 23 analogues and predicted their bioactivity via molecular docking and three-dimensional quantitative structure-activity relationship (3D-QSAR) modeling. Ser2 was identified as a critical site for enhancing receptor affinity. Two analogues, L02 and R01, emerged as potent antagonists of the aphid kinin G-protein-coupled receptor (GPCR), exhibiting strong binding in silico and functional inhibition in cell bioassays in vitro. Laboratory insect tests confirmed significant aphicidal activity, particularly for L02, which demonstrated superior efficacy. These findings highlight the potential of kinin-based GPCR antagonists as environmentally friendly biopesticides, offering target action with reduced nontarget impacts.