Bio‐guided isolation of cholinesterase inhibitors from the bulbs of

In a search for potential acetylcholinesterase (AChE) inhibitors, the ethanol extract of the bulbs of Crinum × powellii (Amaryllidaceae) was found to demonstrate a marked inhibition of this enzyme. Using a bio‐guided isolation strategy, linoleic acid ethyl ester has been identified as the compound responsible for this inhibition. Three other molecules – the alkaloid hippadine, the glycosylated benzyl alcohol derivative calleryanin and 4′‐hydroxy‐7‐methoxyflavan – were also isolated and characterized for the first time from Crinum x powellii. The structures of these compounds were elucidated by spectrometric methods including EI, D/CI mass spectrometry, 1 H, 13 C and 2D NMR experiments. Linoleic acid was also found to inhibit AChE. Copyright © 2005 John Wiley & Sons, Ltd.