In the hospital environment, several factors that lead to microbial dysbiosis contribute to the development of fungal infections caused by yeasts of the genus Candida, with the emergence of resistance already documented. Plant extracts have become potential sources for the discovery of bioactive compounds with antimicrobial activity, as new alternatives for the treatment of antifungal-resistant infections are urgently needed. The objective of this study was to evaluate the antifungal potential of plant extracts against Candida species resistant to commercial antifungal agents, isolated from urine samples of hospitalized patients with candiduria in a university hospital in Minas Gerais.

Yeasts were isolated and identified between March 2021 and January 2023. For yeasts resistant to one or more commercial antifungal agents, susceptibility tests were carried out using five different plant extracts (Amaranthus viridis, Stachys lanata, Glycyrrhiza inflata, Pothomorphe umbellata, and Renealmia petasites) in serial concentrations, by broth microdilution technique, to determine the minimum inhibitory concentration (MIC) of the extract capable of inhibiting fungal growth.

Between 2021 and 2023, 42 yeast isolates of different species showed resistance to one or more tested antifungal drugs and were recovered to evaluate the antifungal potential of the plant extracts. The MIC value was higher than the maximum concentration tested (> 1000 µg/mL) for four of the five extracts (R. petasites, S. lanata, A. viridis, and G. inflata), suggesting that these did not show significant activity against Candida strains resistant to commercial antifungals. Only the extract of P. umbellata showed moderate inhibitory and fungicidal activity against some Candida strains (26.2%), including 5 strains of C. glabrata (19.2%), 5 strains of C. parapsilosis (71.4%), and one strain of C. kefyr (100%).

This study identified a potential antifungal activity for the P. umbellata extract, which remains to be further explored. This finding reinforces the importance of searching for active molecules and potential new drugs, which may provide alternatives to overcome therapeutic limitations, poor bioavailability, and toxicity of current antifungals, as well as the increasing resistance among fungal species.