Flavonoid carbamate hybrids: design, synthesis, and evaluation as multi-target enzyme inhibitors for Alzheimer's disease

Abstract

Alzheimer's disease is characterized by cholinergic dysfunction and neuroinflammation, with acetylcholinesterase and monoacylglycerol lipase emerging as important therapeutic targets. In this study, a series of novel flavonoid carbamate derivatives were synthesized from chrysin and kaempferol, and their structures were confirmed via NMR and HRMS spectroscopy. The inhibitory activities of these compounds were evaluated against acetylcholinesterase and monoacylglycerol lipase using in vitro enzymatic assays. Among them, C3 and C5 exhibited significant dual inhibition, with IC₅₀ values of 22.86 μM and 46.65 μM for monoacylglycerol lipase, and 61.78 μM and 89.40 μM for acetylcholinesterase, respectively. Molecular docking studies revealed key binding interactions, while molecular dynamics simulations demonstrated their stability within the active sites of target enzymes. These findings highlight C3 and C5 as promising candidates for further investigation in the development of dual acetylcholinesterase/monoacylglycerol lipase inhibitors for Alzheimer's disease treatment.

Fig. 1. Design strategy for hybrid flavonoid carbamate derivatives.

Scheme 1. Synthesis of hybrid flavonoid carbamate derivatives from chrysin and kaempferol.

Fig. 2. 3D and 2D interactions of ligands with AChE and MAGL. (A) Interaction between AChE and C3. (B) Interaction between AChE and C5. (C) Interaction between MAGL and C3. (D) Interaction between MAGL and C5.

Fig. 3. The structural stability of AChE and MAGL in both apoprotein and ligand-bound forms was analyzed over a 100 ns MD simulation. Backbone RMSD plots (A) and residue-specific C_α RMSF calculations (B) were used to evaluate structural deviations and flexibility. The radius of gyration (C) provided insights into structural compactness, while SASA measurements (D) assessed solvent exposure throughout the simulation.

Fig. 4. The stability of ligands C3 and C5 in complexes with AChE and MAGL was evaluated using RMSD plots (A) to assess structural deviations over time and RMSF calculations (B) to analyze the flexibility of heavy atoms.

Fig. 5. Ligand-enzyme interaction profiles of C3 and C5 from MD simulations, analyzed using ProLIF (occupancy >30%).

Fig. 6. Three-dimensional FEL derived from RMSD and R_g for enzyme-ligand complexes in MD simulations.