Ion Channels as Targets for Plant-Derived Drugs

Gated ion channels open or close in response to changes in membrane potential, binding of ligands at extracellular or intracellular sites, or mechanical stimuli. Many natural products including plant-derived drugs and plant and animal toxins interfere with the function of ion channels. Here we first discuss neurotoxin binding to voltage-gated ion channels. Nicotine is an agonist for the nicotinic acetylcholine receptor (NAchR). Moreover, many drugs including thujone and synthetic drugs, such as benzamidines, bind to GABA receptors, whereas strychnine antagonizes glycine receptors, e.g. such which mediate feedback signals after muscle contraction. We describe the three isoforms of glutamate receptors and the action of some psychoactive compounds, e.g. ketamine and PCP. Finally, TRPV receptors are briefly touched in connection with their sensing of heat, inflammatory cytokines and the action of capsaicin. In contrast, TRPM8 is described as a cold sensor activated by menthol and related compounds.