Lavandula angustifolia Essential Oil as a Developmental Inhibitor of Candida Species and Biofilms

Background: This research aimed to investigate the antifungal and antibiofilm action of Lavandula angustifolia essential oil (LaEO) against certain Candida species and its toxicity on human keratinocytes. Methods: The minimum inhibitory concentration (MIC) and sessile minimum inhibitory concentration (SMIC) of LaEO were both determined by broth microdilution assays. The influence of LaEO treatment on the ultrastructural morphology of the biofilm and germ tubes was evaluated by scanning electron microscopy (SEM) and light microscopy. In vitro cytotoxicity studies were conducted using human HaCaT epidermal keratinocytes. Results: LaEO showed fungicidal action for all Candida species (125-4000 μg/mL). The SMIC_>90 (C. albicans) ranged between 10,000 and 20,000 μg/mL and resulted in quantitative and qualitative cellular changes. LaEO also inhibited the developmental germ tube kinetics of C. albicans. The 50% cytotoxic concentration (CI₅₀) for HaCaT cells was estimated at 420 μg/mL of LaEO, resulting in a selectivity index (SI) of 0.376 to 5.753 for planktonic cells and 0.056 to 0.321 for biofilm phases. Conclusions: LaEO was found to have antifungal action against Candida species and inhibited the pathogenic morphology of C. albicans. Its antibiofilm effects are comparable to the antifungal agent nystatin, and it can become an important component for the development of natural products applicable to alternative and complementary medicine and dentistry.