Quantity determination of phenolic compounds in some products containing green tea and evaluation of effectiveness against opportunistic fungal infections

Opportunistic fungal infections are considered important public health problems that are difficult to treat, costly, and have high mortality due to increased immuno-compromised individuals and drug resistance to antifungal drugs. Studies showing the use of antifungal phytochemicals externally or internally as adjuvant agents or prophylaxis against complications due to drug resistance and side effects of antifungal medications are included in various articles. Antifungal activity studies have gained importance due to their strong antimicrobial effects, primarily on phenolic compounds. Within the scope of our thesis study, based on the literature showing that the green tea obtained from the Camellia sinensis (L.) O. Kuntze and the phenolic compositions in green tea are related to the antifungal activity; it has been determined that green tea samples were obtained from pharmacies, markets, and the internet in Turkey and food containing green tea. The phenolic content of the supplements was determined by LC-ESI-MS/MS method, and its antifungal activity against C. albicans, C. parapsilosis, C. krusei, and C. glabrata yeasts was investigated. As a result of the study, it was observed that all of the green tea samples affected C. parapsilosis, and C. glabrata species, while antifungal activity was observed in the extracts prepared from three samples of Matcha tea. Within the aim of this study, it was shown for the first time that Matcha tea has an antifungal effect against C. glabrata and C. parapsilosis. When the food supplement samples were examined, it was observed that, unlike the tea samples, the standardized samples, especially on phenolic compounds, showed antifungal effects against C. krusei. None of the samples used in the study showed an antifungal effect against C. albicans. The antifungal effect was suspected to be related to the phenolic compound contents under the literature data. Still, the contents of some compounds causing antagonism, which could not be detected within the analysis, were found in the samples that did not show antifungal activity even though they contained phenolic compounds in similar proportions. It is also thought that it may be related to the presence of chemicals that degrade due to physicochemical reactions during cultivation or storage, chemicals that act as antagonists, or impurities that may cause antagonism. In conclusion, it was observed that more studies on green tea, matcha tea, and food supplements should be done, and positive results were obtained about their use as an adjuvant or prophylactic agent in the treatment of opportunistic fungal infections.