Design, synthesis of new mixed azo-hydroxyquinoline complexes; in vitro anti-inflammatory, antifungal, antibacterial, theoretical, and molecular docking interactions Investigation.

• Novel Co(II) (C1), Ni(II) (C2), & Cu(II) (C3) mixed-ligand complexes have been synthesized. • Their antibacterial, antifungal & anti-inflammatory efficacy have been the focus of recent studies. • The C1, C2, and C3 complexes were found to be more potential anti-inflammatory candidates than the free ligands. • DFT & molecular docking results were correlated with in vitro activities & debated. Here, we combine the simple and readily synthesized azo-ligand [1-((4-Hydroxyphenyl)azo)-2-naphthalenol (PNP)] with 8-hydroxyquinoline (QPH) to develop and synthesize novel Co(II) (C1), Ni(II) (C2), and Cu(II) (C3) complexes. Their antibacterial, antifungal, and anti-inflammatory efficacy had been the focus of recent studies. This objective was reached by first synthesizing and characterizing novel C1, C2, and C3 complexes using elemental analysis, mass spectra, Fourier-transform infrared, electronic spectra, magnetic, Thermal, and molar ratio analysis. Octahedral structures were identified for the C1, C2, and C3 complexes. Quantum chemical characteristics and an optimized molecular structure for each substance were calculated using Density Functional Theory (DFT). To find out whether these substances are efficient in stopping the diffusion of dangerous microorganisms that are the most popular environmental pollutants, a disc diffusion check was carried out. All complexes demonstrated significantly larger inhibition zones (IZ) against both Gram-negative and Gram-positive bacteria compared to free ligands, with increases ranging from 70 % to 134 %. Against fungal strains, C2 and C3 showed the most significant enhancements, exhibiting up to 202 % increase in IZ compared to QPH and PNP. All complexes displayed reductions in minimum inhibitory concentration (MIC) compared to the free ligands against both bacteria and fungi. The most notable reductions were observed against Gram-negative bacteria, with complexes C1-C3 achieving up to 50 % reduction in MIC compared to QPH and PNP. Against fungal strains, complexes C2 and C3 generally showed better activity, with up to a 25 % reduction in MIC compared to the free ligands. Furthermore, the Egg albumin denaturation technique was studied to assess the anti-inflammatory activity. At a concentration of 10 %, C3 exhibited the highest activity at 83.26 %. As the concentration increased to 50 %, C3 maintained its superiority at 83.42%, followed closely by C2 at 78.39 %. At 100 %, C3 again displayed the highest activity at 84.13 %, while C2 and C1 showed comparable activity. Remarkably, at higher concentrations (250 % and 500 %), C3 consistently outperformed all other compounds, reaching an impressive antioxidant activity of 86.29 % at 250 % concentration. The antibacterial, antifungal, and anti-inflammatory activity was assisted by molecular docking investigation against 5JQ9 and 6CLV from Escherichia coli and Staphylococcus aureus , and COX-2 (5IKT) as anti-inflammatory target enzyme, which confirms the bioactivity behavior. In the interaction with 5JQ9, 6CLV, and 5IKT, C3 displayed strong H-donor and ionic interaction with (GLY42 and ASP85), (GLY42 and ASP85) and (CYS41 and GLY45). Notably, C3 consistently exhibited strong interactions across all three receptors, emphasizing its potential as an effective compound. These quantitative results provide valuable insights into the molecular interactions and binding affinities, supporting the bioactivity behavior observed in the experimental assays. In the end, DFT and molecular docking results were correlated with in vitro activities and debated. [Display omitted] [ABSTRACT FROM AUTHOR]