Candida albicans growth and germ tube formation can be inhibited by simple diphenyl diselenides [(PhSe)2, (MeOPhSe)2, (p-Cl-PhSe)2, (F3CPhSe)2] and diphenyl ditelluride

Candida species are the fourth most common cause of nosocomial bloodstream infections. An increase in the frequency of infections, which have become refractory to standard antifungal therapy, has been observed. Recent studies have shown that the pro-oxidant properties of diphenyl diselenide (PhSe)(2), a structurally simple organoselenium compound, can be toxic to yeast. The objective of this work was to study, under non-reactive oxygen species (ROS)-generating conditions, the effect of different organochalcogenide compounds [(PhSe)(2), (PhTe)(2), (MeOPhSe)(2), (p-Cl-PhSe)(2) and (F3CPhSe)(2)] on growth and germ tube formation by Candida albicans. A decrease in C. albicans growth in the presence of crescent concentrations of (PhSe)(2), (PhTe)(2) and (MeOPhSe)(2) was observed. The organochalcogenide compound concentration needed to inhibit 50% (IC50) of the Candida growth was 0.5-2 and 2-10 mu mol l(-1), at a cell density of 10(5) and 10(6) cells ml(-1), respectively. The compounds (p-Cl-PhSe)(2) and (F3CPhSe)(2) were able to inhibit the cell growth, although the inhibition was considerably weaker than that by (PhSe)(2), (PhTe)(2) and (MeOPhSe)(2). In Candida suspensions incubated in a medium containing serum as an inducer of germ tube formation, the presence of either (PhSe)(2) or (MeOPhSe)(2) at 10 mu mol l(-1) completely inhibited the number of cells which formed germ tubes. These results demonstrate the potential of organochalcogenide compounds to inhibit both C. albicans growth and germ tube formation.