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In order to study the structure-activity relationship of Flavokawain B Mannich-based derivatives as acetylcholinesterase (AChE) inhibitors in our recent investigation, 20 new nitrogen-containing chalcone derivatives (4 a-8d) were designed, synthesized, and evaluated for AChE inhibitory activity in vitro. The results suggested that amino alkyl side chain of chalcone dramatically influenced the inhibitory activity against AChE. Among them, compound 6c revealed the strongest AChE inhibitory activity (IC50 value: 0.85 μmol/L) and the highest selectivity against AChE over BuChE (ratio: 35.79). Enzyme kinetic study showed that the inhibition mechanism of compound 6c against AChE was a mixed-type inhibition. The molecular docking assay showed that this compound can both bind with the catalytic site and the peripheral site of AChE.

A new series of-fluoro chalcones-substituted amino-alkyl derivatives (3a˜3l) were designed, synthesized, characterized and evaluated for the inhibitory activity against acetylcholinesterase and butyrylcholinesterase. The results showed that the alteration of fluorine atom position and amino-alkyl groups markedly influenced the activity and the selectivity of chalcone derivates in inhibiting acetylcholinesterase and butyrylcholinesterase. Among them, compound 3l possesses the most potent inhibitory against acetylcholinesterase (IC50  = 0.21 ± 0.03 μmol/L), and the highest selectivity for acetylcholinesterase over butyrylcholinesterase (IC50 (BuChE)/IC50 (AChE) = 65.0). Molecular modeling and enzyme kinetic study on compound 3l supported its dual acetylcholinesterase inhibitory profile, simultaneously binding at the catalytic active and peripheral anionic site of the enzyme.

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Naringin, as a component universal existing in the peel of some fruits or medicinal plants, was usually selected as the material to synthesise bioactive derivates since it was easy to gain with low cost. In present investigation, eight new acacetin-7-O-methyl ether Mannich base derivatives (1-8) were synthesised from naringin. The bioactivity evaluation revealed that most of them exhibited moderate or potent acetylcholinesterase (AChE) inhibitory activity. Among them, compound 7 (IC for AChE = 0.82 ± 0.08 μmol•L, IC for BuChE = 46.30 ± 3.26 μmol•L) showed a potent activity and high selectivity compared with the positive control Rivastigmine (IC for AChE = 10.54 ± 0.86 μmol•L, IC for BuChE = 0.26 ± 0.08 μmol•L). The kinetic study suggested that compound 7 bind to AChE with mix-type inhibitory profile. Molecular docking study revealed that compound 7 could combine both catalytic active site (CAS) and peripheral active site (PAS) of AChE with four points (Trp84, Trp279, Tyr70 and Phe330), while it could bind with BuChE via only His 20.