Substituent Effect in Salicylaldehyde 2-Furoic Acid Hydrazones: Theoretical and Experimental Insights into DNA/BSA Affinity Modulation, Antimicrobial and Antioxidant Activity

Abstract

The biological properties of five aroylhydrazones derived from salicylaldehyde and its 5-substituted derivatives with 2-furoic acid hydrazide were thoroughly investigated. NMR analysis confirmed the predominant existence of the aroylhydrazones in the keto-amine form in aqueous solution. Geometries of these compounds were optimized using density functional theory (DFT) calculations with the B3LYP hybrid functional, while ADMET analysis predicted their pharmacokinetic and toxicological properties. Substituent effects on the interactions between the salicyl aroylhydrazones and BSA and DNA were elucidated through experimental and molecular docking studies, revealing the bromo-substituted hydrazone as the most potent binder to both biomolecular targets. Experimental results aligned well with theoretical predictions, indicating that salicyl hydrazones predominantly act as DNA groove binders. Thermodynamic analysis suggested that the hydrazones predominantly interact with BSA through hydrogen bonding and van der Waals forces. Moreover, antioxidant potential assessment using DPPH, ABTS, FRAP, and metal chelating assays demonstrated the potent antioxidant power of nitro and hydroxy-substituted derivatives. Additionally, the antimicrobial properties of hydrazone against Gram-positive and Gram-negative bacteria, as well as fungi, were thoroughly explored, highlighting the nitro derivative as the most prominent candidate with broad-spectrum antimicrobial potential.