Impact of fermentation conditions on the production of bioactive compounds with anticancer, anti-inflammatory and antioxidant properties in kombucha tea extracts

The production of natural bioactive compounds through the fermentation of plants has increased in recent years. The biological activities of the extracts obtained from the fermentation of black tea with the kombucha consortium were evaluated. To improve the productivity of these compounds two different vessel geometries were used and successive extractions with solvents of increasing polarity were performed. Forty-seven compounds were identified by GC-MS, including several organic acids and phenolic compounds. Total phenolic content, pH value, and antioxidant, antiproliferation and anti-inflammatory activities were measured after 21 days of fermentation. A higher surface/height (s/h) ratio seemed to enhance the anti-inflammatory activity of kombucha tea, resulting in IC50 value of 9.0 +/- 0.1 mu g/mL compared to 24.3 +/- 0.2 mu g/mL with the lowest ratio. Regarding the anticancer activity, the highest inhibition percentage of 55.3% at 50 mu g/mL against the HCT-116 human colon carcinoma cell line was obtained with the ethyl acetate extract after 21 days of fermentation compared to the value of 8% obtained with the same extraction solvent using the non-fermented black tea. These results showed that fermentation may improve the biological activities of the tea and that the production of bioactive compounds can vary depending on the fermentation conditions.