Spectroscopic analysis, DFT and molecular docking study of potent antibacterial agent 4- hydroxy-8-methoxyquinoline-3 carboxylic acid ethyl ester

• FT-IR, FT-Raman, NMR and UV-vis spectra were used to investigate HMCA • DFT calculations were performed using B3LYP/6-311++G (d, p). • HOMO–LUMO, MEP and Mulliken analyses were used to identify reactive site • HMCA shown strong antibacterial activity against S.aureus This study investigates the potential of 4- hydroxy-8-methoxy quinoline-3-carboxylic acid ethyl ester (HMCA) against antibacterial activity by employing different spectroscopic approaches include FT-IR, FT-Raman, NMR, and UV-vis along with bioactive studies such as in vitro analysis and theoretical molecular docking. DFT calculations undertaken at the B3LYP/6-311++ G (d, p) level, show close agreement with the experimental data. Electronic characteristics and UV-visible spectra of HMCA as well as, HOMO-LUMO energies, were analysed by TD-DFT approach (time-dependent). Vibrational spectral analysis was used to evaluate the potential energy distribution (PED) contribution percentages for every mode of vibration. NMR results have shown unique structural characteristics of HMCA. Natural bond orbitals (NBO) were used to examine molecular stability and bond strength. The molecular electrostatic potential (MEP) map future identifies the reactive sites within HMCA. Topological surface analysis such as electron localization function (ELF) and localization orbital locator (LOL) was employed to better comprehend molecular electron density and reactive sites. Pharmacological assessments of HMCA include drug likeness, ADME supports the biological capability. HMCA obeyed the ‘Lipinski’s rule of five’. Preliminary antibacterial experimental analysis showed excellent results. Molecular docking study was conducted, to establish the mechanism by which HMCA inhibit the bacterial growth. These findings identify the titled compound as a crucial scaffold with broad-spectrum antibacterial action.