Kinetics of thymol-induced Candida albicans envelope damage

Scanning electron microscopy was used to study the effects of thymol, an important naturally occurring terpene in thyme oils, at concentrations ranging from 1 to 1/8 MIC on the morphology of Candida albicans yeast cells. The incubation of growing Candida cultures with 1/4, 1/2, and 1 MIC of thymol increased the formation of cells with different types of envelope alterations and the kinetics of this progressive damages was followed at one, two and four hours of incubation. The amphipatic chemical behaviour of thymol allowed it to enter the membrane lipid bilayers, thus altering membrane fluidity and permeability, as well as the function of the membrane-bound enzymes that regulate the synthesis of the polysaccharide components of the cell wall, such as ß-glucan, chitin and mannan, and therefore disturbing cell growth and morphogenesis.The ability of thymol to generate alterations in the Candida envelope underlies its inhibition of major virulence factors, such as: its adhesiveness, its morphological transition to hyphal form, and the resulting infectiousness of this fungus.