Antifungal activity of beta -citronellol against two non-albicans Candida species

beta-citronellol, an acyclic monoterpenoid, inhibits dose-dependent growth of C. glabrata and C. tropicalis with MIC/MFC values of 400 mu g/ml/600 mu g/ml and 100 mu g/ml/200 mu g/ml, respectively. Below MIC, the compound was more toxic to C. glabrata but the inhibition of extracellular proteinases was higher in C. tropicalis. Significant phospholipase activity was not observed in both cases. Membrane ergosterol content decreased at concentrations above MIC/4; inhibition being greater in C. tropicalis. Interestingly at MIC, beta-citronellol showed significantly better ergosterol inhibition in comparison to FLC. At MIC/2, beta-citronellol destabilized fungal cell membrane and cell wall in the presence of cell wall perturbing agents (caspofungin and calcoflour white). Of the two species, C. tropicalis was affected more by DTT and salt-induced stress in the presence of beta-citronellol, severely affecting fungal endoplasmic reticulum and cell surface integrity. beta-citronellol thus alters metabolic activities of both Candida species decreasing growth and viability projecting it as a potential antifungal.