Marine-derived nicotinic receptor antagonist toxins: Pinnatoxins and alpha conotoxins

Nicotinic acetylcholine receptors are evolutionarily conserved ligand gate ion channels that play pivotal roles in neuromuscular and neuronal transmission in a wide range of species. Unsurprisingly, an equally wide range of toxins targeting nicotinic receptors have evolved in numerous terrestrial and marine species. Pinnatoxins and α-conotoxins represent two such groups of marine toxins. While pinnatoxins are macrocyclic small molecules and α-conotoxins are peptidic toxins, both act as potent and selective nicotinic receptor antagonist toxins. As such, both toxin groups can be utilized to study different aspects of nicotinic receptor structure and function. The pharmacological and toxicological insights gained from studying these toxins at an ecological, biological and molecular level have enhanced our knowledge of the importance of nicotinic receptors in both health and disease. Here, the threat of these toxins to animal and human health, their pharmacological and toxicological characteristics, their use as tool compounds and the therapeutic potential of nicotinic toxins are discussed.