A limited therapeutic arsenal is currently available against
Candida infections that show high resistance to
antifungal agents. For this reason, there is a great need to prioritize testing therapeutic agents for the treatment of
candidiasis. The use of
essential oils and their phytoconstituents has been emphasized as a new therapeutic approach. The cell surface hydrophobicity (CSH),
polysaccharide content, antimicrobial activity of
essential oil from Origanum vulgare L. (OVEO), and its two phenolic compounds
carvacrol and
thymol were evaluated in four different Candida spp. (Candida albicans and emerging non-albicans Candida (NAC) species, such as C. glabrata, C. tropicalis, and C. krusei). The results showed the differences between Candida species; for example, C. tropicalis revealed higher resistance than other strains to different natural molecule treatments. The ultrastructural variabilities in the biomembranes and cell walls of these Candida spp. might explain the different biological effects observed after OVEO,
carvacrol and
thymol treatments. Therefore, to study the biological effects of these natural compounds on Candida strains, the samples were observed by confocal
laser scanning microscopy (CLSM) and scanning electron microscopy (SEM). Moreover, the release of cellular materials and their "in vivo" antimicrobial activity on infected G. mellonella larvae were evaluated. The novelty of this study is the demonstration that exists a close correlation between both structural architecture of cell walls and biomembranes' organization with cell fungal responses to
essential oils treatments. Overall, these results suggest practical limits to the predictability.