Studies on the Cytotoxicity and Antioxidant Activity of Tea Kombucha

Abstract

Fermentation of sugared tea with a symbiotic culture of acetic acid bacteria and yeast (tea fungus) yields kombucha tea which is consumed worldwide for its refreshing taste and beneficial effects on human health. It is claimed to prevent various types of cancer and cardiovascular diseases, promote liver function, and stimulate the immune system. The antiproliferative and antioxidant activities of tea kombucha and unfermented tea were, therefore, investigated in this study. The cytotoxic effect of the tea kombucha was studied using an MTT (3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyltetrazolium) assay while its antioxidant activity was performed using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and reducing power (the ferric reducing/antioxidant power (FRAP)) assays. The total phenolic content of the tea kombucha was also studied using the modified Folin-Ciocalteau colorimetric assay. It was observed that the antioxidant activity of tea kombucha was higher compared to the unfermented tea and this reflected in the total phenolics contents. Tea kombucha had 2.4-fold and 7.3-fold significantly (p<0.05) higher phenolic content at concentrations of 2.5 and 5.0 mg/ml, respectively than the unfermented tea. The tea kombucha showed insignificantly low cytotoxicity against the Jurkat P9 leukemia cells many orders of magnitude below that of the standard drug, curcumin, which had an IC50 = 7.22 mg/ml whilst the unfermented tea was without such effect. These results suggest that kombucha tea with its high antioxidant activity may help protect cells against oxidative damage and possibly cancer