Effects of Lemongrass on Candida Albicans Biofilms and Human Cells

Objectives: The persistence of Candida albicans to conventional treatments is well-known today, which indicates the need to search for antimicrobial substances from new sources, including plants used in traditional medicine. The objective of this study was to investigate the effects of Cymbopogon citratus (lemongrass extract, LGE) on C. albicans biofilms developed on acrylic discs used for denture fabrication, and to investigate the cytotoxicity of LGE to peripheral blood mononucleated cells (PBMC).
Methods: The susceptibility of C. albicans (ATCC 18804) to LGE was verified by minimum inhibitory (MIC) and minimum fungicide concentrations (MFC). For biofilm analysis, acrylic discs (10x2mm) were fabricated and had its surface roughness standardized. On saliva-coated discs, biofilms of C. albicans were developed for 72h. After this, discs were immersed in distilled water (control), LGE at MIC, 5xMIC or 10xMIC for 8h. After treatments, biofilms were analyzed by cell counts and metabolic activity. PBMC were obtained using FicollPaque and the cytotoxicity of PBS (control), and LGE at different concentrations was analyzed by MTT assay. Data were analyzed by ANOVA and Tukey's test (p<0.05).
Results: The minimal concentration of LGE required to inhibit C. albicans growth was 6,25 mg/mL. The MFC value observed was 25 mg/mL. The exposure of LGE for 8 hours had a significant effect on biofilms, resulting in lower cell counts (p=0.001) and also lower metabolic activity (p<0.05) compared to the control group. Therefore, there were no significant differences when biofilms were immersed at MIC, 5xMIC or 10xMIC (p>0.05). When compared to the PBS group, which represents a solution without any effect of cytotoxicity, the exposure of human cells to LGE at MIC resulted in similar viability (p>0.05).
Conclusions: The immersion of denture surface in LGE was effective in removing C. albicans biofilms, and MIC represented a safe concentration.