Synthesis, multi-target evaluation and DFT analysis of 6-hydroxychromone derived hydrazones with carbonic anhydrase I-II/acetylcholinesterase inhibition and antioxidant activity

Abstract

Alzheimer's disease seems to be the result of several tumultuous processes such as cholinergic deficits associated with the abnormal metabolic status and oxidative stress that cannot be controlled effectively by single-target molecules. A complex group of agents capable of combining specific enzyme inhibition with antioxidant protection may be seen as an approach toward neuroprotection. The partial synthesis method led to the creation of a new series of chromone hydrazones (3a-p) from substituted hydrazones and 6-hydroxy-chromone. All the newly obtained hydrazones were assayed for their inhibitory activity against acetylcholinesterase (AchE) and human carbonic anhydrases (CA I and II), and their antioxidant potentials were also studied. The chromone-substituted hydrazones 3c, 3e, and 3f exhibited good inhibitory activity against AChE with IC₅₀ values of 0.82 µM, 0.20 µM, and 1.11 µM, respectively. Compound 3e was found to be highly selective for AChE and about six hundred fold more potent as compared to the standard inhibitor, tacrine. Also, these novel chromone derivatives were tested against CA I and II isoenzymes and exhibited IC₅₀ values within the range of 3.16 µM-19.28 µM against CA I and 1.21 µM-14.90 µM against CA II. In addition, in vitro antioxidant assays revealed that compounds 3c, 3e, and 3m exhibited notable radical-scavenging activity, with compound 3e showing superior antioxidant performance (IC₅₀ = 4.17 µg mL^-1 for DPPH and 2.46 µg mL^-1 for ABTS) compared to the reference standard trolox. Furthermore, cytotoxicity studies on HUVEC cells demonstrated that compounds 3c, 3e, and 3m exhibited IC₅₀ values ranging from 52.36 to 60.84 µM. Molecular docking studies described the nature of binding affinities between the synthesized compounds and enzyme targets. DFT-based FMO, MEP, and reactivity analyses demonstrated that the chromone-hydrazone derivatives exhibit narrow HOMO-LUMO gaps and well-defined electrostatic surfaces, supporting their suitability for efficient charge transfer and biological interaction. Moreover, computational simulations and ADME analysis proved that all of the synthesized molecules were druggable with good inhibitory potential.

Fig. 1. Synthesis of compounds 3a–p.

Fig. 2. The SAR analysis of new chromone derivatives.

Fig. 3. Antioxidant activity graphs of compounds 3a–p.

Fig. 4. Overlap of docked conformations of hCA I inhibitors with the co-crystallized inhibitor (represented in black).

Fig. 5. Binding interactions of docked conformations of hCA I inhibitors with surface representation.

Fig. 6. Overlap of docked conformations of hCA II inhibitors with the co-crystallized inhibitor (represented in black).

Fig. 7. Binding interactions of docked conformations of hCA II inhibitors with surface representation.

Fig. 8. Overlap of docked conformations of AChE inhibitors with the co-crystallized inhibitor (represented in black).

Fig. 9. Binding interactions of docked conformations of AChE inhibitors with surface representation.

Fig. 10. MD simulation studies of complex of 3c with hCA 1 for 150 ns; (from top left to right) RMSD plot; protein RMSF graph; ligand RMSF graph, protein ligand contacts, ligand protein contacts, and ligand torsion profile.

Fig. 11. MD simulation studies of complex of 3c with hCA 2 for 150 ns; (from top left to right) RMSD plot; protein RMSF graph; ligand RMSF graph, protein ligand contacts, ligand protein contacts, and ligand torsion profile.

Fig. 12. MD simulation studies of complex of 3c with AChE for 150 ns; (from top left to right) RMSD plot; protein RMSF graph; ligand RMSF graph, protein ligand contacts, ligand protein contacts, and ligand torsion profile.

Fig. 13. HOMO–LUMO energy gap of selected compounds.

Fig. 14. Molecular electrostatic potential for selected compounds.