Synthesis, structure, and antimicrobial activity of a series of novel heterocyclic azo-colorants derived from α-dicarbonyl compounds.

Six novel azo-compounds derived from α-dicarbonyl species, such as 9,10-phenanthrene quinone, squaric acid and ammonium 2,3,5,6-tetraoxo-4-nitropyridinate, were isolated by reactions with a series of heterocyclic hydrazides and characterized by a set of methods. The spectral studies (FT-IR and 1H NMR), together with theoretical DFT modeling and X-ray structure description, of two compounds revealed the hydrazone tautomeric forms of the molecules. Antimicrobial activity against biofilm-forming bacteria was assessed using a turbidimetric method. Growth inhibition was monitored to determine the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) for both Gram-positive and Gram-negative strains. The possibility of a hemolytic effect of the compounds on human red blood cells was evaluated. The ADMET analysis indicated that all the studied compounds obeyed Lipinski's and Veber's rules of the drug discovery pipeline and offered oral bioavailability and positive blood-brain barrier permeability, indicating their potential as therapeutic lead-like compounds. According to the Toxtree analysis, all investigated compounds were categorized as Class I, indicating they belong to the low-toxicity group. The molecular interactions and inhibitory potential underlying the antimicrobial activities of the selected compounds were investigated using molecular docking methods.