Anticandida and antibiofilm activities of extract from Schinopsis brasiliensis Engl. against Candida spp

Abstract

The pathogenic nature of infections caused by Candida spp. underscores the necessity for novel therapeutic agents. Extracts of Schinopsis brasilienses Engl are \ a promising source of agents with antifungal effects. This study aimed to assess the antifungal potential of the leaf extract of S. brasilienses. The antifungal activity was evaluated by determining the minimum inhibitory concentrations and fungicide concentrations (MIC and MFC). The antibiofilm potential was assessed by counting colony-forming units/mL. The study examined the inhibition kinetics of fungal growth and potential synergism between gallic acid or the extract and nystatin using the Checkerboard method. Cytotoxicity was evaluated through the MTT assay. The extract exhibited antifungal effect against all tested strains, with MIC and MFC ranging from 31.25-250 μg/mL. Gallic acid, the main isolated compound, displayed a MIC of 2000 μg/mL. The extract of S. brasilienses at 31.25 μg/mL inhibited the formation of biofilm by C. albicans and significantly reduced the mass of mature biofilm after 24 and 48 h (p < 0. 05). At a concentration of 125 μg/mL, the extract demonstrated significant inhibition of fungal growth after 6 hours. The combination of gallic acid or extract with nystatin did not exhibit synergistic or antagonistic effect. Furthermore, the extract did not induce cytotoxicity to a human cell line. The extract of S. brasiliensis demonstrates antifungal activity against Candida, generally exhibiting fungicidal action and capacity to inhibit biofilm formation as well as reduce mature biofilms. Additionally, the extract showed low cytotoxicity to human cells.

Figure 1. Kinetics test showing the behavior of the S. brasiliensis extract, nystatin, and control at the MICx4 concentration during 24 hours (*p < 0.05).

Figure 2. Cytotoxicity of the S. brasiliensis extract against HEK-293 cell line for 72 hours using the MTT assay. Data are presented as the mean ± SEM of three independent experiments, tested in different concentrations (3.9–500 µg/mL), in quadruplicate. DMSO at 20% was used as a positive control. *p <0.05 vs control analyzed by one-way analysis of variance (ANOVA) followed by Tukey’s post-test.