Inhibition of quorum sensing regulation and stress tolerance by Rhodomyrtus tomentosa extracts and rhodomyrtone as an alternative treatment for zoonotic pathogens

Vet World Vol.18 April-2025 Article-13

Research Article

Veterinary World, 18(4): 877-887

https://doi.org/10.14202/vetworld.2025.877-887

Sukanlaya Leejae¹, Watcharapong Mitsuwan², Ozioma F. Nwabor³, and Supayang Piyawan Voravuthikunchai⁴

1. School of Languages and General Education, Drug and Cosmetics Excellence Center, Walailak University, Nakhon Si Thammarat, 80160, Thailand.
2. Akkhraratchakumari Veterinary College, Research Center of Excellence in Innovation of Essential Oil, and One Health Research Center, Walailak University, Nakhon Si Thammarat, 80160, Thailand.
3. Department of Public Health, Syracuse University, Syracuse, NY13244, USA.
4. Center of Antimicrobial Biomaterial Innovation-Southeast Asia, Faculty of Science, Prince of Songkla University, Songkhla, 90112, Thailand.

Background and Aim: Staphylococcus aureus is a zoonotic pathogen with significant public health and economic implications. Its ability to tolerate environmental stress and regulate virulence through quorum sensing contributes to its persistence and pathogenicity. Rhodomyrtus tomentosa and its bioactive compound rhodomyrtone have demonstrated antimicrobial properties against Gram-positive, multidrug-resistant bacteria. This study aimed to evaluate the effects of these agents on quorum sensing inhibition and stress tolerance in S. aureus and Pseudomonas aeruginosa, providing insights into their potential as alternative antimicrobial strategies.

Materials and Methods: The anti-quorum sensing activity of R. tomentosa extracts was assessed using Chromobacterium violaceum as a bioindicator. In addition, the effects on P. aeruginosa swarming motility were evaluated. Stress tolerance in S. aureus was examined by subjecting treated cells to acidic (pH = 5.0), alkaline (pH = 9.0), osmotic (7.5% NaCl), heat (43°C), and oxidative (1 mM H₂O₂) stress conditions. The survival rates were determined through colony-forming unit (CFU) counts following treatment with rhodomyrtone and ethanol leaf extracts.

Results: The ethyl acetate fraction of R. tomentosa leaf extract exhibited the highest violacein inhibition, followed by the ethanol extract. At 256 μg/mL, these extracts permitted P. aeruginosa colony formation but inhibited its swarming motility. Regarding stress tolerance, no surviving S. aureus cells were detected under any stress condition after 3–6 h of treatment with 2 × minimum inhibitory concentration (MIC) (1 μg/mL) of rhodomyrtone. In addition, 4 × MIC (128 μg/mL) of the ethanol leaf extract inhibited pathogen survival under all tested stress conditions except for alkaline and oxidative stresses.

Conclusion: The findings suggest that R. tomentosa extracts and rhodomyrtone effectively inhibit quorum sensing and stress tolerance, offering a promising alternative antimicrobial approach. These compounds could be utilized in veterinary medicine and food safety to mitigate zoonotic pathogen contamination and combat antibiotic-resistant infections.

Keywords: anti-quorum sensing, Pseudomonas aeruginosa, rhodomyrtone, Rhodomyrtus tomentosa, Staphylococcus aureus, stress tolerance.

How to cite this article: Leejae S, Mitsuwan W, Nwabor OF, and Voravuthikunchai SP (2025) Inhibition of quorum sensing regulation and stress tolerance by Rhodomyrtus tomentosa extracts and rhodomyrtone as an alternative treatment for zoonotic pathogens, Veterinary World, 18(4): 877–887.

Received: 27-10-2024 Accepted: 11-03-2025 Published online: 19-04-2025

Corresponding author: Sukanlaya Leejae E-mail: sukanlaya.le@wu.ac.th

DOI: 10.14202/vetworld.2025.877-887

Copyright: Leejae, et al. This article is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http:// creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.