Pharmacological and mechanistic assessment of Trachyspermum ammi hydrosol: antimicrobial and anti-biofilm efficacy against Staphylococcus aureus and Listeria monocytogenes.

The escalating global threat of antimicrobial resistance (AMR), particularly among biofilm-forming bacterial pathogens, has necessitated the development of novel therapeutic strategies. Trachyspermum ammi hydrosol has exhibited a range of bioactive properties. However, its potential as a dual-action antimicrobial agent targeting both planktonic and biofilm-associated microorganisms remains underexplored. This study aimed to explore the antibacterial and antibiofilm activity of T. ammi hydrosol (TaHy) against two major Gram-positive pathogens, Staphylococcus aureus (S. aureus) and Listeria monocytogenes (L. monocytogenes), and elucidate its mechanism of action based on cell. Additionally, we aimed to evaluate in vivo acute toxicity and biosafety. Antimicrobial activities were assessed using DDA, MIC, and time-kill assays. Antibiofilm activity was evaluated using a crystal violet method, and biofilm morphology was examined by microscopy. TaHy demonstrated efficient inhibition in hydrophobicity and EPS production, along with alterations in membrane integrity, including bacteriolysis and protein and nucleic acid release. Our results showed that the MIC of TaHy was 0.625 mg/mL against both pathogens and that it significantly inhibited and eradicated biofilm formation at sub-MIC values, as confirmed by SEM and fluorescence microscopy. TaHy effectively inhibited hydrophobicity and EPS production, reducing the virulence factors of pathogens to 1/8 MIC. Consequently, in vivo acute oral toxicity tests revealed no adverse effects at doses up to 2000 mg/kg body weight of hydrosol concentrate. These findings revealed that TaHy has robust antimicrobial and antibiofilm capability against S. aureus and L. monocytogenes.