Decoding the Benzaldehyde Pharmacophore: Structural Determinants for Enhancing Antibacterial Efficacy and Food Safety

Phytocompounds undoubtedly are structurally diverse and play a crucial role in the development of novel therapeutic agents. 2-Hydroxy-4-methoxybenzaldehyde (HMB), from Hemidesmus indicus, is a potent antibacterial agent. Yet its pharmacophore has not been mechanistically defined. Here, we deconstructed HMB through a panel of structural derivatives to delineate the core structural determinants driving activity against foodborne pathogens. Structure-activity analysis revealed that the core benzaldehyde structure, rather than HMB itself, is the minimal active pharmacophore, with specific functional substitutions modulating antibacterial activity and membrane affinity. Integrating an experimental membrane assay with molecular dynamics simulations provided the first atomistic insight into how these derivatives interact with bacterial membrane lipids, demonstrating that substituent-driven modulation of hydrogen bonding dictates antibacterial potency. Specifically, electron-withdrawing groups enhanced membrane penetration and depolarization, particularly in Gram-positive pathogens. Time-kill kinetics and functional assays confirmed bactericidal action via membrane disruption rather than DNA interaction. Crucially, the active derivatives exhibited negligible cytotoxicity toward mammalian Vero cells, confirming their potential as selective and safe natural preservatives. This work provides a mechanistic blueprint for designing benzaldehyde-based antibacterials to combat antimicrobial resistance.