Table 1: Inhibitory activity (IC50) and selectivity index (SI) of the compounds investigated against AChE and BChE.

CompoundsIC50 ( M ± SD) SI
AChEBChE

Galanthamine1.18 ± 1.05/
0.8 [21]7.3 [21]9.13
Harmane7.11 ± 2.0076.91 ± 1.5710.82
Harmine9.05 ± 1.0875.07 ± 1.298.30
Harmaline10.58 ± 2.01101.39 ± 1.399.58
Harmol21.58 ± 1.398.21 ± 3.650.38
Harmalol27.88 ± 1.139.48 ± 2.030.34
Vasicine13.68 ± 1.252.60 ± 1.470.19
Nigellastrine II40.46 ± 1.099.26 ± 1.470.23
Nigellastrine I70.50 ± 1.1418.24 ± 3.230.26
Vasicinone370.78 ± 1.07
Deoxyvasicinone294.44 ± 1.47
Deoxyvasicine
1,2,3,4-tetrahydroharmane-3-carboxylic acid

IC50 values were determined by regression analyses and expressed as the means ± SD of three replicate determinations. SI is the AChE selectivity index defined as IC50 BChE/IC50 AChE affinity ratio.
—: no inhibitory activity.