Dihydro-β-erythroidine hydrobromide(DHβE) is a potent, oral active and competitive antagonist of neuronal nicotinic acetylcholine receptors (nAChRs). Dihydro-β-carotene hydrobromide showed selectivity to α4β4 and α4β2nAChR, with IC50 of 0.19 and 0.37 μM,