The Synergistic Effect of Combining Natural Compounds 1,8-cineole (Eucalyptol) and Naringenin with 11 Antibiotics of Different Drug Classes
DOI:
https://doi.org/10.58445/rars.2676Keywords:
1 8-Cineole, Eucalyptol, Naringenin, antibiotics, antibiotic resistance, efflux pump inhibitors, membrane permeabilizersAbstract
Antibiotic resistance represents a critical global health threat, as increasingly prevalent bacterial infections become more challenging to treat with existing antibiotics. Millions of lives are lost to infections caused by antibiotic-resistant bacteria, highlighting the urgent need for innovative strategies to combat this resistance. This study investigates the efficacy of two natural compounds, 1,8-Cineole (Eucalyptol) and Naringenin, in combination with eleven antibiotics of various drug classes, as antibiotic adjuvants to enhance the efficacy of existing antibiotics to combat resistance. Both compounds exhibit antimicrobial properties and are known to have mechanisms of action similar to efflux pump inhibitors and membrane permeabilizers. Eucalyptol has demonstrated antimicrobial effects through membrane disruption, and Naringenin damages bacterial membranes. The aim of this research is to evaluate the synergistic effects of these natural compounds against Escherichia coli, as there is no current research on the potential effects of combining these specific compounds with any antibiotics. Using broth microdilution assays and a derivative of checkerboard assays, Minimum Inhibitory Concentration (MIC) values, Area Under Growth (AUC) values, and Inhibitory Concentration 50% (IC50) values were compared to identify any potential synergistic interactions. It is hypothesized that both Eucalyptol and Naringenin will enhance antibiotic effectiveness. Results of this study demonstrate a synergistic effect occurred when Eucalyptol was combined with Azithromycin. In contrast, antagonistic interactions were found when Eucalyptol was combined with Tetracycline and Kanamycin, and when Naringenin was combined with Trimethoprim. This research holds significant implications for addressing the growing challenge of antimicrobial resistance by identifying novel compound combinations for restoring the efficacy of existing antibiotics and by expanding potential for new combinations for other applications.
References
Antimicrobial Resistance Collaborators. (2022). Global burden of bacterial antimicrobial resistance in 2019: A systematic analysis. The Lancet, 399(10325), 629–655. https://doi.org/10.1016/S0140-6736(21)02724-0
Darbandi, A., Asadi, A., Mahdizade Ari, M., Ohadi, E., Talebi, M., Halaj Zadeh, M., Darb Emamie, A., Ghanavati, R., & Kakanj, M. (2021). Bacteriocins: Properties and potential use as antimicrobials. Journal of Clinical Laboratory Analysis, 36(1), e24093. https://doi.org/10.1002/jcla.24093
Delcour, A. H. (2009). Outer membrane permeability and antibiotic resistance. Biochimica et Biophysica Acta (BBA) - Proteins and Proteomics, 1794(5), 808–816. https://doi.org/10.1016/j.bbapap.2008.11.005
Dhanda, G., Acharya, Y., & Haldar, J. (2023). Antibiotic adjuvants: A versatile approach to combat antibiotic resistance. ACS Omega, 8(12), 10757–10783. https://doi.org/10.1021/acsomega.3c00312
Echeverría, J., Opazo, J., Mendoza, L., Urzúa, A., & Wilkens, M. (2017). Structure-activity and lipophilicity relationships of selected antibacterial natural flavones and flavanones of Chilean flora. Molecules, 22(4), 608. https://doi.org/10.3390/molecules22040608
Evans, J., Hannoodee, M., & Wittler, M. (2024). Amoxicillin clavulanate. StatPearls. https://www.ncbi.nlm.nih.gov/books/NBK538164/
Fong, C. R., Bittick, S. J., & Fong, P. (2018). Simultaneous synergist, antagonistic and additive interactions between multiple local stressors all degrade algal turf communities on coral reefs. Journal of Ecology, 106(4), 1390–1400. https://doi.org/10.1111/1365-2745.12914
Habboush, Y., & Guzman, N. (2023, June 20). Antibiotic resistance. StatPearls. https://www.ncbi.nlm.nih.gov/books/NBK513277/
Hoch, C. C., Petry, J., Griesbaum, L., Weiser, T., Werner, K., Ploch, M., Verschoor, A., Multhoff, G., Bashiri Dezfouli, A., & Wollenberg, B. (2023). 1,8-Cineole (eucalyptol): A versatile phytochemical with therapeutic applications across multiple diseases. Biomedicine & Pharmacotherapy, 167, 115467. https://doi.org/10.1016/j.biopha.2023.115467
Kapoor, G., Saigal, S., & Elongavan, A. (2017). Action and resistance mechanisms of antibiotics: A guide for clinicians. Journal of Anaesthesiology Clinical Pharmacology, 33(3), 300–305. https://doi.org/10.4103/joacp.joacp_349_15
Khanna, N. R., & Gerriets, V. (2020). Beta lactamase inhibitors. StatPearls. https://www.ncbi.nlm.nih.gov/books/NBK557592/
Lamp, K. C., & Vickers, M. K. (1998). Pharmacodynamics of ampicillin-sulbactam in an in vitro infection model against Escherichia coli strains with various levels of resistance. Antimicrobial Agents and Chemotherapy, 42(2), 231–235. https://doi.org/10.1128/aac.42.2.231
Merghni, A., Belmamoun, A. R., Urcan, A. C., Bobiş, O., & Lassoued, M. A. (2023). 1,8-Cineol (eucalyptol) disrupts membrane integrity and induces oxidative stress in methicillin-resistant Staphylococcus aureus. Antioxidants, 12(7), 1388. https://doi.org/10.3390/antiox12071388
Patel, P., Wermuth, H. R., Calhoun, C., & Hall, G. A. (2023, May 26). Antibiotics. StatPearls. https://www.ncbi.nlm.nih.gov/books/NBK535443/
Pathania, R., Sharma, A., & Gupta, V. (2019). Efflux pump inhibitors for bacterial pathogens: From bench to bedside. Indian Journal of Medical Research, 149(2), 129. https://doi.org/10.4103/ijmr.ijmr_2079_17
Salehi, B., Fokou, P., Sharifi-Rad, M., Zucca, P., Pezzani, R., Martins, N., & Sharifi-Rad, J. (2019). The therapeutic potential of naringenin: A review of clinical trials. Pharmaceuticals, 12(1), 11. https://doi.org/10.3390/ph12010011
Tosh, P. K. (2024, March 29). Protect yourself from superbugs. Mayo Clinic. https://www.mayoclinic.org/diseases-conditions/infectious-diseases/expert-answers/superbugs/faq-20129283
Verma, P., Tiwari, M., & Tiwari, V. (2022). Potentiate the activity of current antibiotics by naringin dihydrochalcone targeting the AdeABC efflux pump of multidrug-resistant Acinetobacter baumannii. International Journal of Biological Macromolecules, 217, 592–605. https://doi.org/10.1016/j.ijbiomac.2022.07.065
Wang, Y., Zhang, Y., Song, X., Fang, C., Xing, R., Liu, L., Zhao, X., Zou, Y., Li, L., Jia, R., Ye, G., Shi, F., Zhou, X., Zhang, Y., Wan, H., Wei, Q., & Yin, Z. (2022). 1,8-Cineole inhibits biofilm formation and bacterial pathogenicity by suppressing luxS gene expression in Escherichia coli. Frontiers in Pharmacology, 13, 988245. https://doi.org/10.3389/fphar.2022.988245
World Health Organization. (2022, June 22). Lack of innovation set to undermine antibiotic performance and health gains. https://www.who.int/news/item/22-06-2022-22-06-2022-lack-of-innovation-set-to-undermine-antibiotic-performance-and-health-gains
World Health Organization. (2024, June 25). Building evidence for the use of bacteriophages against antimicrobial resistance. https://www.who.int/europe/news/item/25-06-2024-building-evidence-for-the-use-of-bacteriophages-against-antimicrobial-resistance
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