Mechanistic insights into citral-induced cellular damage and its antibacterial efficacy against Listeria monocytogenes

Abstract

Citral is widely recognized as a membrane-targeting antimicrobial, with its bactericidal activity primarily dependent on the degree of membrane damage. This study reveals its dual mechanism involving oxidative assault against Listeria monocytogenes (L. monocytogenes). The induced cytotoxic effects appear closely associated with citral's interaction with bacterial cell membrane components and the resultant sustained membrane dysfunction. Our results showed that sublethal concentrations of citral induced rapid depolarization in L. monocytogenes while progressively increasing membrane permeability. Following 1 h of citral exposure, the intracellular generation of reactive oxygen species peaked. Further investigations indicated that citral could directly interact with and alter the chemical structure of reduced glutathione (GSH). Notably, exogenous GSH supplementation significantly attenuated citral's antimicrobial efficacy, suggesting that its biochemical reactivity targeting glutathione and related thiol-containing proteins plays a critical role in the antibacterial action against L. monocytogenes. Importantly, regardless of growth inhibition, all tested concentrations of citral significantly suppressed the hemolytic activity of L. monocytogenes. Overall, this study provides valuable insights into the antimicrobial mechanisms of citral, particularly at low concentrations.