Bufotenidine
Bufotenidine, also known as 5-hydroxy-N,N,N-trimethyltryptammonium (5-HTQ) or as cinobufagine, is an indole toxin related to bufotenin, serotonin, and other tryptamines which is found in the venom of a variety of toads. It acts as a selective serotonin 5-HT3 receptor agonist, and has been used in scientific research to study the function of the serotonin 5-HT3 receptor, though this use has been limited by the fact that, as a quaternary amine, it is unable to readily cross the blood-brain-barrier and hence is peripherally selective.