Synergistic effects of tea catechin epigallocatechin gallate and antimycotics against oral Candida species.
OBJECTIVE
Epigallocatechin gallate (EGCG), the major antimicrobial tea polyphenol, has been reported to inhibit the growth of Candida albicans planktonic cells and enhance the antifungal activity of antimycotics. We hypothesised that synergism exists between EGCG and conventional antimycotics against biofilms of Candida species.


METHODS
The minimal inhibitory concentrations (MIC) of EGCG, miconazole, fluconazole and amphotericin B against planktonic cells and the sessile MIC (SMIC) against biofilms of Candida albicans, Candida parapsilosis, Candida tropicalis, Candida glabrata, Candida kefyr and Candida krusei were determined by a microdilution method. For assessment of biofilm metabolic activity, the 2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide (XTT) assay was used. The interactions between EGCG and antimycotics were evaluated by checkerboard microdilution assay and determined by fractional inhibitory concentration index (FIC).


RESULTS
Synergism was observed between EGCG and miconazole, fluconazole or amphotericin B against most test planktonic and biofilm cells of Candida species (FIC≤0.5). All biofilm cells were significantly more resistant to EGCG and antimycotics (20-3200 times higher) compared with their planktonic counterparts.


CONCLUSIONS
We conclude that EGCG enhances the antifungal effects of miconazole, fluconazole and amphotericin B. Combined treatment with EGCG may lower the dosages of antimycotics, thus preventing adverse effects and the emergence of drug-resistant oral Candida species.
Department of Pediatric Dentistry, College of Dentistry, University of Illinois at Chicago, Chigago, IL, USA; Guangdong Provincial Key Laboratory of Stomatology, Guanghua School of Stomatology, Sun Yat-sen University, Guangzhou, Guangdong, China. Electronic address: dentistningyang@aliyun.com.
Yang
Y
Ning
Guangdong Provincial Key Laboratory of Stomatology, Guanghua School of Stomatology, Sun Yat-sen University, Guangzhou, Guangdong, China. Electronic address: lingjq@mail.sysu.edu.cn.
Junqi
J
Ling
Department of Pediatric Dentistry, College of Dentistry, University of Illinois at Chicago, Chigago, IL, USA. Electronic address: chriswu@uic.edu.
Christine D
CD
Wu
D000666:Amphotericin B / Q000494:pharmacology; D000813:Anilides / Q000494:pharmacology; D000935:Antifungal Agents / Q000494:pharmacology*; D018441:Biofilms / Q000187:drug effects; D002175:Candida / Q000187:drug effects* / Q000502:physiology; D002392:Catechin / Q000031:analogs & derivatives* / Q000737:chemistry / Q000494:pharmacology; D004357:Drug Synergism; D015725:Fluconazole / Q000494:pharmacology; D008825:Miconazole / Q000494:pharmacology; D008826:Microbial Sensitivity Tests; D059808:Polyphenols / Q000494:pharmacology; D013778:Tetrazolium Salts / Q000494:pharmacology
C548251:2,3-bis (2-methyloxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide; D000813:Anilides; D000935:Antifungal Agents; D059808:Polyphenols; D013778:Tetrazolium Salts; D008825:Miconazole; D000666:Amphotericin B; D002392:Catechin; D015725:Fluconazole; C045651:epigallocatechin gallate
Antifungal agents; Candida species; Epigallocatechin gallate; Synergism