From Bedside to Bench and Back Again: Exploratory Analysis of the Role of Essential Oils as Potential Treatment of Fungal Keratitis

Authors

  • Celso Costa Department of Ophthalmology, Unidade Local de Saúde de Coimbra, Coimbra, Portugal https://orcid.org/0000-0002-7111-1002
  • Elijah Akegbe Faculty of Medicine of the University of Coimbra (FMUC), Coimbra, Portugal
  • João Pinheiro Costa Department of Ophthalmology, Unidade Local de Saúde de São João, Porto, Portugal
  • Dolores Pinheiro Department of Clinical Pathology, Unidade Local de Saúde de São João, Porto, Portugal
  • Nuno Mesquita University of Coimbra, Centre for Functional Ecology (CFE), Department of Life Sciences, Faculty of Sciences and Technology, Coimbra, Portugal
  • Célia Cabral Clinical Academic Center of Coimbra (CACC), Coimbra, Portugal; University of Coimbra, Center for Innovative Biomedicine and Biotechnology (CiBB), Coimbra, Portugal; University of Coimbra, Centre for Functional Ecology (CFE), Department of Life Sciences, Faculty of Sciences and Technology, Coimbra, Portugal; University of Coimbra, Coimbra Institute for Clinical and Biomedical Research (iCBR), Faculty of Medicine, Coimbra, Portugal
  • Anália Carmo Department of Microbiology, Unidade Local de Saúde de Coimbra, Coimbra, Portugal
  • Rui Tomé Department of Microbiology, Unidade Local de Saúde de Coimbra, Coimbra, Portugal
  • Elisa Julião Campos Clinical Academic Center of Coimbra (CACC), Coimbra, Portugal; Faculty of Medicine of the University of Coimbra (FMUC), Coimbra, Portugal; University of Coimbra, Center for Innovative Biomedicine and Biotechnology (CiBB), Coimbra, Portugal; University of Coimbra, Centre for Chemical Engineering and Renewable Resources for Sustainability (CERES), Department of Chemical Engineering, Faculty of Sciences and Technology, Coimbra, Portugal; University of Coimbra, Center for Neuroscience and Cell Biology (CNC-UC), Coimbra, Portugal
  • Esmeralda Costa Department of Ophthalmology, Unidade Local de Saúde de Coimbra, Coimbra, Portugal; Faculty of Medicine of the University of Coimbra (FMUC), Coimbra, Portugal
  • João Gil Department of Ophthalmology, Unidade Local de Saúde de Coimbra, Coimbra, Portugal; Unidade de Oftalmologia de Coimbra (UOC), Coimbra, Portugal
  • Andreia Rosa Department of Ophthalmology, Unidade Local de Saúde de Coimbra, Coimbra, Portugal; Unidade de Oftalmologia de Coimbra (UOC), Coimbra, Portugal
  • Maria João Quadrado Department of Ophthalmology, Unidade Local de Saúde de Coimbra, Coimbra, Portugal; Unidade de Oftalmologia de Coimbra (UOC), Coimbra, Portugal

DOI:

https://doi.org/10.48560/rspo.38196

Keywords:

Antifungal Agents, Keratitis/therapy, Oils, Volatile

Abstract

INTRODUCTION: This study aimed to evaluate the antifungal efficacy of essential oils (EOs) extracted from medicinal plants, one native in Côa Valley (Portugal): Lavandula pedunculata (Mill.) Cav. and another not-native: Cymbopogon citratus (DC.) Stapf, against fungal keratitis (FK) pathogens.
METHODS: Corneal specimens were collected from patients suspected of having infectious keratitis from Unidade Local de Saúde de Coimbra (Coimbra) and Unidade Local de Saúde de São João (Porto). The confirmed fungal isolates were then identified and characterized. In addition to testing the sensitivity to conventional antifungals, the susceptibility to the selected EOs was also assessed at various concentrations, through in vitro solid-phase disk diffusion assays, determining their inhibitory and fungicidal properties. The inhibition zone diameters (IZD) formed around the paper discs were recorded on the 3rd, 5th, 7th, 10th and 14th day of incubation.
RESULTS: Fourteen positive samples were obtained in 6 months. A predominance of Candida spp. was noted. Cymbopogon citratus demonstrated exceptional antifungal activity, with complete inhibition of Aspergillus fumigatus and Scedosporium apiospermum across all concentrations, maintaining maximum IZDs throughout the study period. Against Candida species, the IZD for Cymbopogon citratus increased over time, with the 100% concentration achieving an IZD from 68 mm on day 3 to 81.7 mm by day 14 for Candida albicans and from 51.7 mm to 71.3 mm for Candida parapsilosis. Lavandula pedunculata EO displayed initial high activity against Aspergillus fumigatus, with a decrease in IZDs over time for lower concentrations. Its effectiveness against Scedosporium apiospermum and Candida species demonstrated concentration and time-dependent variability.
CONCLUSION: Cymbopogon citratus and Lavandula pedunculata EOs may be potent antifungal agents against FK pathogens, providing a basis for the development of new antifungal treatments. The remarkable efficacy of Cymbopogon citratus against a range of fungal pathogens supports its use in clinical practice, while Lavandula pedunculata requires further studies to clarify its antimicrobial potential. Optimizing EOs concentrations and exposure duration seems to be important to maximize antifungal efficacy. Further research is needed to understand the role of these EOs in the corneal mileu and contribute to the development of new drugs.

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Published

2025-02-14

How to Cite

Costa, C., Akegbe, E., Pinheiro Costa, J. ., Pinheiro, D., Mesquita, N., Cabral, C., Carmo, A., Tomé, R., Julião Campos, E. ., Costa, E., Gil, J., Rosa, A., & Quadrado, M. J. (2025). From Bedside to Bench and Back Again: Exploratory Analysis of the Role of Essential Oils as Potential Treatment of Fungal Keratitis. Revista Sociedade Portuguesa De Oftalmologia. https://doi.org/10.48560/rspo.38196

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