Assessment of the Antifungal Effect of Camellia sinensis Extracts on Candida albicans and Candida parapsilosis Strains: An in vitro Study

Background: Oral candidiasis is a common infection caused by Candida species, Candida albicans and Candida parapsilosis being the most prevalent strains. Objectives: To assess the antifungal effects of Camellia sinensis (green tea) extracts on standardized Candida albicans and Candida parapsilosis strains, depending on the extraction solvent and extract concentration. Materials and Methods: Extracts with concentrations of 25 and 50% were prepared, using methanol and ethanol as solvents. A 0.5 McFarland concentration and approximate 2x106 CFU/mL suspension of each Candida strain was prepared. The four types of extracts were applied on unimpregnated culture medium. A Dimethyl sulfoxide solution was used as negative control, and a fluconazole impregnated disc was used as positive control. After a 24 hr incubation period, the inhibition zones were measured. The minimum inhibitory concentration was determined. Results: The largest inhibition zone was measured for the positive control, while the negative control showed no inhibitory effect. The 50% concentration extracts showed larger inhibition zones compared to 25% concentration, for both ethanol and methanol solvents and for both Candida albicans and Candida parapsilosis strains, but lower compared to the positive control. No significant differences were determined when comparing the antifungal effects of same concentration extracts prepared with methanol and ethanol as solvents. Conclusion: The green tea extract shows the ability to inhibit the growth of standardized Candida albicans and Candida parapsilosis stains. Its efficacy increases with concentration, and is not dependent on the solvent type.