Antifungal Activity of Black Tea Polyphenols (Catechins and Theaflavins) against <i>Candida </i>Species

Abstract

<i>Background/Aims:</i> The polyphenols catechins and theaflavins in black tea have been shown to possess many medicinal properties, including anticancer activity and some antifungal characteristics, but there have been few studies of their anti-<i>Candida</i> activity. In this paper we report the results of our study of the anti-<i>Candida</i> activity of tea polyphenols. <i>Methods:</i> The effects of 4 different concentrations of catechins and theaflavins were evaluated on 5 isolates each of 5 <i>Candida </i>species employing an agar diffusion growth inhibition assay. The minimum inhibitory concentration (MIC) of the polyphenols against <i>C. albicans </i>was determined. The post-antifungal effect (PAFE) of the polyphenols for <i>C. albicans </i>was investigated. <i>C. albicans</i> cells exposed to polyphenols were studied using a scanning electron microscope (SEM). <i>Results:</i> Both polyphenols showed anti-<i>Candida</i> activity against all tested <i>Candida</i> species and demonstrated a MIC of 6.25 mg/ml for <i>C. albicans</i>. <i>C. glabrata</i> was found to be the most sensitive species followed by <i>C. parapsilosis, C. albicans, C. krusei </i>and <i>C. tropicalis </i>(p < 0.05 for all). Significant intraspecies variations in sensitivity were noted among <i>C. parapsilosis</i> and <i>C. tropicalis</i> (p < 0.001) for both polyphenols. Theaflavins displayed standard PAFE while catechins showed a paradoxical PAFE with all isolates of <i>C. albicans</i>. SEM revealed considerable cell wall damage of <i>C. albicans</i> cells exposed to the polyphenols. <i>Conclusion:</i> The study reveals for the first time the anti-<i>Candida</i> properties of black tea polyphenols that may find therapeutic applications in future.