Anti- <i>Trichophyton rubrum</i> potential, association with fluconazole, and mechanism of action of ( <i>R</i> )-(+)-citronellal

<i>Trichophyton rubrum</i> is a keratolytic and keratinophilic fungus responsible for causing dermatophytoses. These pathogens have been associated with resistance phenomena, which encourages the need to search for new substances with anti-Trichophyton rubrum activity. The present study aimed to investigate the antifungal activity of (<i>R</i>)-(+)- Citronellal (RCIT) against clinical isolates of <i>T. rubrum</i>. The antifungal potential of RCIT was evaluated from the Minimum Inhibitory Concentration (MIC), Minimum Fungicide Concentration (MFC), Association study, and assays with cholesterol, ergosterol and sorbitol. RCIT MIC values ranged from 4 to 512 µg/mL, while their MFC ranged from 4 to 512 µg/mL. When associating RCIT with the drug fluconazole, pharmacological indifference and antagonism were evidenced. It was shown that the mechanism of action is related to fungal ergosterol and showed interactions with exogenous cholesterol. The results obtained in this research demonstrate that RCIT has the potential to become a product for the treatment of dermatophytosis.