Oxazosulfyl, a Novel Sulfyl Insecticide, Binds to and Stabilizes the Voltage-Gated Sodium Channels in the Slow-Inactivated State

Oxazosulfyl is the first representative of a novel sulfyl class of insecticides with a potent and cross-spectrum insecticidal activity, albeit with an unclear mechanism of action. As a potential agent of pest control in rice fields, we investigated the action of oxazosulfyl on the nervous system and voltage-gated sodium channels in insects. After the injection of 10 μg of oxazosulfyl, American cockroaches (Periplaneta americana) were quickly paralyzed, which persisted for more than 7 days. Extracellular recordings revealed a depressed spontaneous nerve activity in the cockroaches injected with oxazosulfyl, which specifically affected the voltage-gated sodium channels (in German cockroaches (Blattella germanica) expressed in Xenopus oocytes) in the slow-inactivated state resulting in the inhibition of sodium currents. The potency of oxazosulfyl and other sodium channel blockers to block sodium channels was consistent with their insecticidal activity. Thus, we conclude that the action mode of oxazosulfyl involves the state-dependent blockage of voltage-gated sodium channels.