Inhibition of acetylcholinesterase

The inhibition of acetylcholinesterase (AChE) was determined in 96 microplates using the method by Ellman et al. (1961) with some modifications. Each well contained 25 μl of 15 mM ATCI in Millipore water, 125 μl of 3 mM DTNB in buffer C (50 mM Tris–HCl, pH 8, 0.1 M NaCl, 0.02 M MgCl2 6 H2O), 50 μl buffer B (50 mM Tris–HCl, pH 8, 0.1% bovine serum), and 25 μl of test compound or extract. Every concentration was tested in triplicates. Then, 25 μl and 0.22 U/ml AChE were added and the absorbance was measured eight times every 13 s at 405 nm. Galantamine was used as reference.