Investigation of bioactive properties, structural, electronic, reactivity analysis and quantum-based characterization of hexadecanamide

Hexadecanamide (HDA), a long-chain fatty acid amide, was identified as a key bioactive constituent in the
extract of Aegle marmelos using GC-MS analysis and chosen for further theoretical and biological studies. Density
functional theory (DFT) was used to examine the molecular structure and vibrational properties of HDA at the
B3LYP/6-311++G(d,p) level. The computed results were compared with the experimental FT-IR and UV-visible
spectra. The structural stability of the molecule was confirmed by the optimized geometrical parameters, which
showed good agreement with the available experimental data. To comprehend the chemical reactivity and
stability of HDA, the electronic properties, such as HOMO–LUMO energies, energy gap, chemical hardness,
softness, and electrophilicity index, were assessed. Charge delocalization and intramolecular interactions were
examined using Natural Bond Orbital (NBO) analysis, and electrophilic and nucleophilic reactive sites were
identified using the Molecular Electrostatic Potential (MEP) surface. The theoretical and experimental UV-Vis
absorption bands correlated well, according to TD-DFT calculations. The binding affinity of HDA with the
target protein was further investigated by molecular docking studies, which revealed advantageous interactions
through hydrophobic and hydrogen bonding contacts. HDA's potential as a bioactive therapeutic candidate is
supported by the combined experimental and computational results, which indicate that it has strong structural
stability and encouraging biological activity.