(±)Epibatidine

Epibatidine is an analgesic alkaloid isolated from the skin of the poison frog Epipedobates tricolor. It is the most potent nicotinic acetylcholine receptor agonist known. The natural (+) enantiomer is only 2-fold more potent than the (-) enantiomer with respect to analgesic activity in mice. Both enantiomers bind with high affinity (K_i=0.045 and 0.058 nM respectively) to rat brain membrane nicotinic receptors.