In vitro activity of xanthorrhizol against Candida glabrata, C. guilliermondii, and C. parapsilosis biofilms

Abstract

The formation of Candida biofilms has important clinical ramifications, because these biofilms exhibit increased resistance to conventional antifungal therapies. The aim of this study was to investigate the activity of xanthorrhizol on biofilms produced by non-C. albicans Candida (NCAC) species, including C. glabrata, C. guilliermondii, and C. parapsilosis. NCAC biofilms were generated in flat-bottom 96-well microtiter plates and quantified using the XTT (2, 3 – bis (2-methoxy-4-nitro-5-sulfophenyl)-5-[(phenyl amino) carbonyl]-2H-tetrazolium hydroxide) reduction assay. The NCAC biofilms at adherent, intermediate, and mature growth phases were treated with 0.5–512 μg/ml of xanthorrhizol for 24 h. The ranges of sessile minimum inhibitory concentrations (SMICs) of xanthorrhizol against C. glabrata, C. guilliermondii, and C. parapsilosis biofilms were 8–32 μg/ml, 8–16 μg/ml, and 8–64 μg/ml, respectively. Xanthorrhizol affected cell density that had an indirect effect on the biofilm OD₄₉₀. The compound eradicated the viable cells of the C. glabrata and C. parapsilosis biofilms at the adherent growth phase at 16 μg/ml and that of C. guilliermondii at 8 μg/ml. Treatment with 128 μg/ml of xanthorrhizol reduced the OD₄₉₀ of C. glabrata, C. guilliermondii, and C. parapsilosis biofilms at the mature growth phase by 77.8%, 88.5%, and 64.5%, respectively. These results indicate that xanthorrhizol exhibits potent activity against NCAC biofilms in vitro. Therefore, xanthorrhizol has potential therapeutic value in treating biofilm-associated NCAC infections and should be further evaluated in vivo.

Keywords:

• amphotericin B
• biofilms
• non-Candida albicans Candida (NCAC)
• xanthorrhizol

Acknowledgements

This work was supported by the Korea Foundation for International Cooperation of Science & Technology (KICOS) through a grant provided by the Korean Ministry of Science & Technology (MOST) in 2007 (No. 2006-8-1797) and by the Yonsei Biomolecule Research Initiative of the Brain Korea 21 Project.

Declaration of interest: The authors report no conflicts of interest. The authors are responsible for the content and writing of the manuscript.

This paper was first published online on Early online on 11 June 2010.