BINDING OF TROPANE ALKALOIDS TO NICOTINIC AND MUSCARINIC ACETYLCHOLINE RECEPTORS

Fourteen tropane and related alkaloids were analyzed for their affinit y for nicotinic and/or muscarinic acetylcholine receptors. The biogene tic intermediates littorine, 6 beta-hydroxyhyoscyamine, 7 beta-hydroxy hyoscyamine exhibit similar affinities at the muscarinic receptor as s copolamine and atropine. The quarternary derivatives N-methylatropine and N-methylscopolamine show the highest binding with IC50 values of l ess than 100 pM and 300 pM, respectively. The tropane alkaloids (inclu ding cocaine) also bind to the nicotinic acetylcholine receptor, albei t with much lower affinities.