KCNQ3 activation by the naturally occurring phenol, eugenol

Pharmacological targeting of ion channels represents a crucial avenue for pain management. The KCNQ family of ion channels plays a significant role controlling neuronal excitability and the generation and propagation of pain-related nerve impulses, mitigating excessive electrical signaling and limiting the transmission of pain signals. Eugenol has a variety of biological activities, including analgesic and anti-inflammatory properties. When used in conjunction with the anti-inflammatory drug diclofenac, eugenol demonstrates enhanced analgesic efficacy in animal models. We investigated the effects of eugenol on KCNQ ion channels. Eugenol acts as a KCNQ2/3 activator, shifting the voltage dependency to negative potentials, most of the activation can be explained by the effect on the KCNQ3, molecular docking simulation and mutagenesis experiments suggest that the binding pocket of eugenol is located at the top of the voltage-sensing domain. We show also that eugenol is a weak activator of the TRPV1 channel yet inhibits the capsaicin and acidic pH activated current. Diclofenac also inhibits the TRPV1 channel current. In cells co-expressing KCNQ2/3 and TRPV1, eugenol and diclofenac limit the extent of membrane depolarization. Altogether, we report a new target for eugenol that adds to its wide array of biological activities, including its role in modulating acute pain.