This study aimed to evaluate the antifungal activity of the aqueous extract from leaves of burdock [Arctium minus (Hill) Bernh.] by determining the Minimum Inhibitory Concentration (MIC) and the Minimum Fungicidal Concentration (MFC) on different species and strains of Candida genus. The species Candida albicans, C. tropicalis, C. glabrata, C. stellatoidea, C. dubliniensis, and C. Krusei were included in this study. Four C. albicans and three C. tropicalis strains were used, whereas only one strain of each remaining species was tested. Such yeasts were used in this study due to their importance and frequency in the oral cavity. The yeasts were subjected to treatments with aqueous extract concentrations that ranged from 0.09 to 25 mg mL-1. Concentrations lower than 12.5 mg mL-1 were not enough to present fungicidal or fungistatic effect. The concentration of 12.5 mg mL-1 had fungistatic effect on most tested strains and species (C. albicans 04A and ATCC44858; C. tropicalis 23600 and 23651; C. glabrata; C. stellatoideia; C. dubliniensis; and C. krusei). However, fungicidal effect was only observed on the species C. krusei (MFC=12.5 mg mL-1). A distinct performance was observed among different strains from the same species (for C. albicans and C. tropicalis). Thus, the antifungal action of A. minus (Hill) Bernh. aqueous extract is probably associated with the genetic variability present among the different strains of one same species and among different species; besides, concentrations lower than 12,5 mg mL-1 did not have an effect on the tested yeasts. The adopted methodology and considering the limitations of this study led to the conclusion that the aqueous extract of A. minus presented antifungal effect, mainly fungistatic, against oral Candida species. However, new studies are needed to evaluate its real antifungal potential inside the oral environment.
Arctium minus; Candida; antifungal activity; Asteraceae; medicinal plants
