The Amaryllidaceae alkaloids: an untapped source of acetylcholinesterase inhibitors

The AChE inhibitory activity of alkaloid extracts and compounds has been in the focus of research on the plants of Amaryllidoideae subfamily since the approval of galanthamine in 2001 by FDA for treatment of mild to moderate Alzheimer's disease. A small fraction of the huge biodiversity of the plants producing Amaryllidaceae alkaloids has been studied as a source of AChE inhibitors. Less than 20% of the known Amaryllidaceae alkaloids have been tested in vitro for their ability to inhibit AChE. Galanthamine, lycorine and haemanthamine are scaffolds for semi-synthesis of potent AChE inhibitors. In the last years, galanthamine has been studied in silico for drug optimization and synthesis of potent dual-binding AChE inhibitors. In silico studies of other Amaryllidaceae alkaloids have also provoked the interest of researchers in the last years. The aim of this article is to provide a comprehensive review on studies of the AChE inhibitory activity of extracts and compounds from the plants of Amaryllidoideae subfamily covering the literature from the last two decades.