Antifungal and antibiofilm activity of Lippia microphylla Cham. essential oil. (Verbenaceae) on Candida albicans and human cell cytotoxicity

Abstract

Objective

This study evaluated the antifungal activity of Lippia microphylla essential oil (LM-EO) on Candida albicans.

Design

In vitro assays were conducted to test LM-EO for its anti-Candida effects, antibiofilm activity, effects on the fluorescence intensity of Candida albicans biofilms observed via confocal microscopy, probable mechanism of action, and toxicity on human keratinocytes. Statistical analysis was performed considering α = 5 %.

Results

The minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) of LM-EO ranged from 128 µg/mL to 256 µg/mL and 256 µg/mL to 1024 µg/mL, respectively. MIC values did not change in the presence of sorbitol, whereas a 4-fold increase was observed in the presence of ergosterol, suggesting that LM-EO may act on the cell membrane. This was subsequently observed via confocal microscopy using propidium iodide markers. LM-EO reduced biofilm adherence by 66–86 % (p < 0.0001) at low concentrations (256–2560 µg/mL); however, it showed toxicity in human cells.

Conclusions

LM-EO exhibited fungicidal activity likely through a mechanism related to ergosterol complexation but demonstrated cytotoxicity to human keratinocytes.