Eleven Amaryllidaceae alkaloids (1-11) were isolated from fresh bulbs of Chlidanthus fragrans Herb. The chemical structures were elucidated by MS, and 1D and 2D NMR spectroscopic experiments. Complete NMR assignments were achieved for deoxypretazzetine (1). All compounds were evaluated for their erythrocytic acetylcholinesterase and serum butyrylcholinesterase inhibition activity using Ellman's method. In the prolyl oligopeptidase assay, Z-Gly-Pro-p-nitroanilide was used as substrate. In biological assays, only the crinine type Amaryllidaceae alkaloid undulatine showed promising acetylcholinesterase and prolyl oligopeptidase inhibition activity with IC50 values of 23.0 +/- 1.0 microM and 1.96 +/- 0.12 mM, respectively. Other isolated compounds were considered inactive.

ADINACO Research Group Faculty of Pharmacy Charles University Heyrovského 1203 500 05 Hradec Králové Czech Republic

Centre of Advanced Studies Faculty of Military Health Sciences University of Defence Trebesská 1575 Hradec Králové 500 01 Czech Republic

Department of Inorganic and Organic Chemistry Faculty of Pharmacy Charles University Heyrovského 1203 500 05 Hradec Králové Czech Republic

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