Properties and role of the quorum sensing molecule farnesol in relation to the yeast Candida albicans.

Farnesol is a quorum sensing (QS) molecule synthesized by Candida albicans acting as a negative regulator of morphogenesis; it blocks the yeast-to-hyphae transformation. This molecule is currently studied in particular from the viewpoint of possible use as a substance with anticancer properties and with an antimicrobial, and anti-biofilm effect in yeasts resistant or tolerant to conventional therapeutic agents, for example fluconazole. Besides the aforementioned effect on morphological transformation through cyclic AMP (cAMP)/protein kinase A (cAMP-PKA) pathway, it also affects other biochemical pathways of yeasts, for example those ones for sterol biosynthesis or triggering of apoptosis via accumulation of ROS (reactive oxygen species) that damage essential cellular compartments. ROS activate intracellular caspases that are indicators of apoptotic response in C. albicans. However, an influence of farnesol on C. albicans yeasts is dependent on used concentrations; while higher concentrations (200 - 300 μM) are stressful for yeasts, lower concentrations (about 40 μM) protect them from stress. This QS molecule is also able to modulate efflux pumps in resistant yeasts. This review provides an overview of the current knowledge about production, role, and mode of action of farnesol in the clinically most important yeast C. albicans.