AChE inhibitory activity of N-substituted natural galanthamine derivatives.

Galanthamine derivatives are known for their AChE inhibitory activity. Among them, galanthamine has been approved for treatment of Alzheimer's disease. N-Acetylnorgalanthamine (narcisine) and N-(2'-methyl)allylnorgalanthamine (the most potent natural AChE inhibitor of galanthamine type) were synthetized using N-norgalanthamine as a precursor. The NMR data described previously for narcisine were revised by two-dimensional H-H and H-C chemical shift correlation experiments. AChE inhibitory assays showed that N-acetylnorgalanthamine and N-formylnorgalanthamine (with previously unknown activity) are 4- and 43-times, respectively, less potent than galanthamine. In vitro (AChE inhibitory) and in silico (docking, ADME) assays and comparison of N-(2'-methyl)allylnorgalanthamine with galanthamine prove that this molecule is a very promising natural AChE inhibitor (33-times more potent than galanthamine) which further in vivo studies would provide better estimation about its applicability as a drug.