1-Alkyl-1,2,5,6-tetrahydropyridine-3-carboxaldehyde-O-alkyl-oximes: A new class of potent orally active muscarinic agonists related to arecoline

Article abstract of DOI:10.1016/0223-5234(91)90128-A

On the basis of the knowledge acquired for basic studies of several known arecoline derivatives about the structural requirements for potent agonistic activity and oral efficacy, a series of 1-alkyl-1,2,5,6-tetrahydropyridine-3-carboxaldehyde-O-alkyl-oximes was synthesized and biologically evaluated in a battery of in vitro and in vivo assays. The most interesting molecules to emerge from the primary screening, 1,2,5,6-tetrahydropyridine-3-carboxaldehyde-O-methyloxime hydrochloride (11, RU 35963), 1-methyl-1,2,5,6-tetrahydropyridine-3-carboxyaldehyde-O-methyloxime hydrochloride (12, RU 35926), and 1,2,5,6-tetrahydropyridine-3-carboxyaldehyde-O-propargyloxime hydrochloride (30, RU 47029) and 1-methyl-1,2,5,6-tetrahydropyridine-3-carboxaldehyde-O-propargyloxime hydrochloride (33, RU 35986), were evaluated more extensively, and their cholinomimetic profile was compared with that of the parent molecule, arecoline. The pharmacological results after oral administration to mice and rats revealed that their efficacy is 2-3 orders of magnitude higher than that of arecoline, and, in addition, they show a longer duration of action. The 4 aldoximes showed anti-amnesic properties in many respects superior to those of arecoline. Their anti-amnesic doses were 2 orders of magnitude lower than those inducing obvious cholinergic symptoms, and 3-5 orders of magnitude lower than the lethal doses. These new compounds can be regarded as potential candidates for clinical studies in AD (Alzheimer's disease) patients.