Antifungal activity of different essential oils against Malassezia pathogenic species.

Plants produce essential oils in response to physiological stresses, pathogen attacks and ecological factors. Nowadays, they are recognized as defence compounds and attractors of pollinators. Essential oils have been traditionally used in the past years in various cultures for medicinal and health purposes. In recent times due to their well-documented antimicrobial activities, essential oils have consolidated their use in raw and processed food preservation, health and clinical uses.The potential activity of essential oils against the largely diffused Malassezia species on the human skin, which can cause common infections or exacerbate multiple skin disorders, such as P. versicolor, folliculitis, seborrheic dermatitis and dandruff, atopic dermatitis and psoriasis.Information on essential oils activity against Malassezia species was obtained from published materials, including books and electronic databases, such as SCI finder, PubMed, Web of Science, ACS, Science Direct, Wiley, Springer, Taylor, J-STAGE and Google Scholar. Search was conducted covering the period from January 2013 to December 2018.

In the in vitro studies diverse methods were used to test the essential oils activity, namely broth microdilution method, which resulted the most used one, followed by agar disk diffusion and vapour phase methods. Essential oils obtained by steam distillation were from different plant genera, Thymus, Artemisia, Malaleuca, Cinnamomun, Ocimum, Zataria, Rosmarinus, Origanum, Syzigium, Foenicolum, Thapsia, Tachyspermum, Myrtus. MIC values were expressed as μg/mL, μL/mL and by inhibition zone (mm) or μL/cm³. All the investigated essential oils were active at the tested conditions. In addition, two clinical studies used essential oils from Cymbopogon citratus and C. flexuosus formulated in shampoo, cream or lotion for the successful treatment of dandruff and P. versicolor.

Results of these studies indicate worthy prospects for clinical application of essential oils and there is an urgent need to conduct further in vivo studies with large number of patients in order to verify the clinical potential of essential oils against Malassezia species.