Antifungal activity and influence of propolis against germ tube formation as a critical virulence attribute by clinical isolates of Candida albicans

Abstract

The potentiality to switch between yeast and hyphal morphologies plays an important role in the virulence of Candida albicans (C.albicans). The objective of the present study was to evaluate the chemical composition, antifungal activity and influence of propolis upon germ tube formation of C.albicans clinical isolates. The major compounds of propolis ethanolic extract (PEE) was revealed by gas chromatography-mass spectrometry (GC/MS) analysis. Broth microdilution method was used for determination of minimal inhibitory concentration (MIC) and minimal fungicidal concentration (MFC) of this extract. C.albicans isolates were exposed to sub-MIC concentrations of propolis and germ tube reduction percent (GRP) and morphological transition from yeast to filamentous form were monitored microscopically. Phenolic compounds, aromatic acids, aliphatic acids, sugars and polycyclic aromatic hydrocarbons were the major compound classes in PEE. Mean of MIC and MFC values of PEE against C.albicans isolates were 360.6μg·mL-1 and 1250.1μg·mL-1, respectively. The increase in concentration led to a significant reduction in germ tube formation, so mean of GRP was 36.7±11.1 and 22±10.1 at concentration of ½ MIC and ¼ MIC of PEE, respectively. In conclusion, the present study indicated that PEE has interesting potential as a therapeutic agent that targets germ tube formation by C.albicans as a critical virulence factor.