In vitro Inhibition of Growth and Virulence Factors Production in Azole-Resistant Strains of Non-albicans Candida by Cinnamomum verum, Cymbopogon citratus, Cymbopogon martini and Syzygium aromaticum Essential Oils

Abstract

In the present study, oils of Cinnamomum verum, Cymbopogon citratus, Cymbopogon martini and Syzygium aromaticum and their major active compounds eugenol, cinnamaldehyde, citral and geraniol were studied for their efficacy in inhibiting growth and virulence factors (cell surface hydrophobicity, proteinase and haemolysin) production in the azole-resistant strains of non-albicans Candida. All the test oils exhibited significant antifungal activity; however, C. martini and cinnamaldehyde were most active (MIC range 45-200 μg/ml). Time-kill assays revealed relatively higher fungicidal activity by geraniol, eugenol, cinnamaldehyde and C. verum compared to other oils against C. tropicalis 01. At 0.5 × MIC, C. verum, C. citratus, C. martini, S. aromaticum, cinnamaldehyde and eugenol exhibited >70 % reduction in the production of proteinase in the test strains. Cinnamaldehyde at 50 μg/ml exhibited a reduction of 78.90 % in the production of haemolysin whereas % CSH was reduced from 60.97 to 26.89 in C. tropicalis 01. Our study has highlighted the promising and broad spectrum in vitro growth inhibition and anti-virulence activity of oils of S. aromaticum, C. verum, eugenol and cinnamaldehyde against drug-resistant strains of Candida spp and suggests their possible new mode of anti-infective action.

Keywords:

• Anti-virulence
• cell surface hydrophobicity
• essential oils
• haemolysin
• proteinase