Piperamides, which are secondary metabolites in the genus Piper, have potent insecticidal activity, and have thus inspired the development of novel insecticides. In this study, piperovatine, a piperamide from Piper piscatorum (Piperaceae), was investigated using a two-electrode voltage clamp to clarify its detailed mode of action against voltage-gated sodium channels, a classic target. In Xenopus oocytes expressing voltage-gated sodium channels from German cockroach (Blattella germanica), piperovatine induced inward currents depending on repetitive openings. For instance, maximal currents were generated with 10 μM piperovatine following 100 trains of depolarizing pulses with frequency 25 Hz. Piperovatine also shifted the half-activation voltage after conditioning pulses from -35 mV to -45 mV. In addition, piperovatine-modified currents were correlated with not only the number of prior conditioning pulses but also the proportion of activated channels. Finally, piperovatine was found to stabilize voltage-gated sodium channels in the fast-inactivated state after opening, and inhibit transition to the slow-inactivated state. These results suggest that piperovatine preferably binds to activated channels and stabilizes voltage sensors at the conformation acquired during depolarization.

哌啶是Piper属的次生代谢产物，具有强大的杀虫活性，因此激发了新型杀虫剂的开发。在这项研究中，使用两电极电压钳研究了来自Piper piscatorum（Piperaceae）的哌酰胺的哌丁丙啶，以阐明其针对经典的靶控电压门控钠通道的详细作用方式。在非洲爪蟾卵母细胞中表达德国蟑螂（德国小att）的电压门控钠通道），哌拉维汀感应的内向电流取决于重复的开口。例如，在100串频率为25 Hz的去极化脉冲之后，用10μM的哌伏汀产生最大电流。在调节脉冲后，哌伐他汀还将半激活电压从-35 mV转移到-45 mV。另外，哌咯丙汀修饰的电流不仅与先前的调节脉冲的数量相关，而且与激活的通道的比例相关。最后，发现哌罗维汀在打开后能使电压门控钠通道稳定在快速灭活状态，并抑制过渡到慢速灭活状态。这些结果表明哌维他汀优选结合至活化的通道并使电压传感器稳定在去极化过程中获得的构象上。