• Journal of the Korean Society of Food Science and Nutrition
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• v.45 no.10
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• pp.1422-1429
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• 2016

Kombucha is a slightly sour beverage fermented by symbiotic micro-organisms, including bacteria and yeasts. In this study, we examined the biological activities of citrus Kombucha (CK) produced by addition of citrus extract to original Kombucha (K). After fermentation for 10 days, radical scavenging activity examined by ABTS and DPPH assays increased by approximately 20% compared to that of K. Moreover, content of total phenolic compounds significantly increased by 60% compared to that of K. Cell proliferation assays utilizing MTT showed that CK treatment significantly inhibited growth of bladder cancer cells, T-24 and 5637, in a dose-dependent manner with $IC_{50}$ values of 4 and 7 mg/mL, respectively. Annexin V staining showed that CK treatment led to apoptosis of cells in a dose-dependent manner. T-24 cells were more sensitive to CK treatment than 5637 cells, as 8 mg/mL of CK resulted in 97% apoptosis of T-24 cells. Western blotting showed that CK treatment led to up-regulation of apoptotic proteins, including caspases-3, -8, -9, and PARP, in bladder cells not in K-treated cells. Taken together, these results demonstrate that CK may be developed as a functional beverage.

• Journal of the Korean Society of Food Science and Nutrition
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• v.45 no.12
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• pp.1838-1842
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• 2016

Kombucha (K) is a fermented beverage made from black tea by symbiotic micro-organisms of bacteria and yeasts. To enhance bio-activities of K, we produced citrus/green tea Kombucha (CK) by adding extracts of citrus peel and green tea obtained from Jeju Island. ORAC assays showed that anti-oxidative capacity of CK increased by approximately 3-folds compared to K. We examined anti-cancer properties of extracts from citrus peel and/or green tea using 5637 human bladder cancer cells and B16F10 murine melanoma cells. Proliferation of B16F10 cells was markedly inhibited at concentrations higher than $10{\mu}L/mL$. At a concentration of $20{\mu}L/mL$, anti-cancer activities of extracts were in the order of citrus peel< green tea< combination of both. Interestingly, a combination of both extracts showed a synergistic effect on inhibition of growth of cancer cells. CK fermented with citrus peel and green tea extracts showed enhanced anti-cancer activity compared to K. Cytotoxicity of CK on RAW 264.7 murine macrophages was negligible up to $100{\mu}L/mL$. Taken together, these results indicate that citrus Kombucha is safe to be developed as a functional beverage.

• Journal of the Korean Society of Food Science and Nutrition
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• v.46 no.7
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• pp.896-902
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• 2017

In this study, we investigated citrus Kombucha (CK) produced by three different bacteria strains (Gluconacetobacter xylinus, Gluconacetobacter medellinensis, and Gluconobacter oxydans; named as CK-MOX) identified from traditional Kombucha. During fermentation, the pH level of CK-MOX was gradually reduced, and total acidity slightly increased. Antioxidant activity, measured by DPPH, ABTS, and oxygen radical absorbance capacity assays, markedly increased after fermentation. Moreover, fermented CK-MOX (Day15) exhibited anti-proliferative and anti-migratory activities against EJ human bladder carcinoma cells. Western immunoblot assays showed that treatment with CK-MOX significantly up-regulated phospho-extracellular signaling kinase (ERK) levels. To distinguish whether or not up-regulation of phospho-ERK is the cause or effect, we investigated the viability of EJ cells in the presence of U0126, a mitogen activated protein kinase/ERK kinase 1/2 inhibitor. Pre-treatment with U0126 rescued cells from CK-MOX-induced cell death, which indicates phospho-ERK may be a key regulator in the mechanism of CK-MOX-induced apoptosis of EJ bladder cancer cells. In conclusion, CK-MOX, fermented by a defined composition of bacterial starters, shows antioxidant capacity and anti-cancer activity against EJ bladder cancer cells.