Evaluation of the synergistic antifungal effect of combinations of essential oils and rhamnolipid in Trichophyton rubrum

• Grant number: 25/03760-3
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: August 01, 2025
• End date: July 31, 2026
• Field of knowledge: Health Sciences - Pharmacy - Pharmacognosy
• Principal Investigator: Daiane Cristina Sass
• Grantee: Ana Beatriz Felipe de Souza
• Host Institution: Instituto de Biociências (IB). Universidade Estadual Paulista (UNESP). Campus de Rio Claro. Rio Claro , SP, Brazil

Abstract

Onychomycosis is a fungal infection that affects the nails, mainly caused by fungi, with Trichophyton rubrum being the main etiological agent. This species of fungus thrives in moist and warm environments, such as closed shoes and swimming pool areas, which facilitates its proliferation and spread. Oral treatment is generally effective, but the toxicity of medications, the appearance of multidrug-resistant fungi and the length of treatment make adherence to medication difficult. Therefore, safe and effective alternative therapies are extremely necessary for successful treatment. Several essential oils have antifungal activity, and some in association with chemical drugs can reduce the effective dose of these. Essential oils of tea tree, citronella and oregano are known to have antifungal activity, including against Trichophyton rubrum. However, the application of essential oils is limited due to their hydrophobic nature, making it necessary to produce formulations with emulsifying agents appropriate for commercial applications. Rhamnolipids are glycolipid biosurfactants that, in addition to having antimicrobial potential, have emulsifying properties, which allows them to be mixed with essential oils to form emulsions, which have better applicability, especially for topical therapeutic treatments, increasing the bioavailability of the active ingredient, and can also increase antimicrobial activity (synergistic effect). In this sense, this project aims to evaluate the antifungal action, as well as the synergistic effect of emulsions formed by rhamnolipid and essential oils against Trichophyton rubrum.