Natural medicine can substitute antibiotics in animal husbandry: protective effects and mechanisms of rosewood essential oil against Salmonella infection

Aniba rosaeodora essential oil (RO) has been traditionally used in natural medicine as a substitute for antibiotics due to its notable antidepressant and antibacterial properties. Salmonella, a prevalent pathogen in foodborne illnesses, presents a major challenge to current antibiotic treatments. However, the antibacterial efficacy and mechanisms of action of RO against Salmonella spp. remain underexplored. This study aims to elucidate the chemical composition of RO, evaluate its antibacterial activity and mechanisms against Salmonella in vitro, and further delineate its anti-inflammatory mechanisms in vivo during Salmonella infection. Gas chromatography-mass spectrometry (GC-MS) was utilized to characterize the chemical constituents of RO. The antibacterial activity of RO was assessed using minimal inhibitory concentration (MIC) and time-kill assays. Various biochemical assays were employed to uncover the potential bactericidal mechanisms. Additionally, mouse and chick models of Salmonella infection were established to investigate the prophylactic effects of RO treatment. RO exhibited significant antibacterial activity against both Gram-positive and Gram-negative bacteria, with an MIC of 4 mg·mL⁻¹ for Salmonella spp. RO treatment resulted in bacterial damage through the disruption of lipid and purine metabolism. Moreover, RO reduced injury and microbial colonization in infected mice and chicks. RO treatment also modulated the host inflammatory response by inhibiting proinflammatory pathways. In conclusion, our findings demonstrate that RO is effective against Salmonella infection, highlighting its potential as an alternative to antibiotics for antibacterial therapy.