The inhibition modes of both cholinesterases caused by the selected potent compound 4b were investigated by the graphical analysis of steady-sate inhibition data (Figure 4). Reciprocal plots (lineweaver-Burk plots) describing compounds 4b inhibition showed that the point of the curves intersect at the secondary quadrant. This pattern indicated the mixed-type inhibition. The results revealed that these compounds were likely to bind both of the active site and PAS of both cholinesterases.