Unfolded and macrocyclic ammonium derivatives of diterpenoids steviol and isosteviol having choline moieties. Synthesis and inhibitory activities toward acetylcholine- and butyrylcholinesterases
A series of unfolded and macrocyclic ammonium derivatives of diterpenoids isosteviol 2 and steviol 17 possessing choline moieties have been synthesized and assayed for inhibitory activities toward AchE and BchE. Compounds 5–8, 13, 16, 20, and 21 showed moderate activity within the range of IC50 values 8.0 × 10−4 to 2.2 × 10−6 mol L−1. Isosteviol derivative 16 exhibited the best inhibition selectivity against acetylcholinesterase among the compounds tested. It inhibited AchE of human erythrocytes at IC50 = 80 μM, whereas inhibition of BchE occurred at IC50 > 1000 μM.