In order to further investigate the binding modes of Mannich bases derivatives with cholinesterases, we carried out molecular docking studies for the selected potent compound 4b by Surflex-Dock suite implemented in SYBYL 8.0 software. The PDB codes of 3D crystal structures of human AChE and BuChE are 1EVE and 1P0I, respectively. As shown in Figure 5A, the most energetically favorable binding mode of compound 4b at the active site of AChE comes into a free binding energy of −7.14 kcal/mol. The MOLCAD surface modeling with cavity depth potential shows that compound 4b extends into the deep cavity of the binding pocket of AChE (Figure 5B). Compound 4b occupied to the central hydrophobic region of the binding pocketed arranged by Tyr70, Tyr121, Trp279 and Phe290. It is clearly demonstrated that compound 4b extends from the anionic subsite of the active site near Trp84 to PAS region near Trp279. Besides, aromatic ring of compound 4b also forms π-π interactions with Trp279 (Figure 5C). Moreover, the dendrimer-shaped motif at the aromatic ring of compound 4b may effectively prevent the interaction of catalytic triad of AChE with substrate. These interaction and occupation of compound 4b with the subsites of AChE explains its mixed inhibition type.