Changes in the chemical profile and bioactive potentialities of Kombucha fermented Salvia aegyptiaca tea

Abstract

Kombucha is a traditionally non-alcoholic drink prepared by fermenting sweet-flavored black tea with tea fungus. In the present study, Salvia aegyptiaca tea was used as alternative substrate for kombucha fermentation due to its bioactivity which could improve the functional characteristics of kombucha. The prepared infusions (unfermented controls, without and with sugar) and fermented aqueous extracts were subjected to liquid-liquid extraction with ethyl acetate (EtOAc) and n-butanol (n-BuOH), sequentially, then compared in terms of their total phenolic content (TPC), antioxidant, anti-acetylcholinesterase (AChE), anti-inflammatory (anti-15-lipoxygenase), anti-xanthine oxidase (XOD) and cytotoxic activities. The kombucha beverage was obtained after longer period (11 days). Results indicated that fermentation reduced TPC in all extracts compared to unfermented samples (without and with sugar). The antioxidant capacity of S. aegyptiaca was enhanced by fermentation of n-BuOH (89%) and EtOAc (85%) extracts and inversely reduced in aqueous fraction. Nineteen phenolic compounds were identified and quantified using HPLC (high-performance liquid chromatography), whereas different aromatic compounds were detected using GC-MS (gas chromatography-mass spectrometry). The AChE, XOD and 15-lipoxygenase inhibitory effects as well as cytotoxic activity of all extracts were reduced by fermentation. The obtained results suggested that S. aegyptiaca tea is probably not suitable as substrate for kombucha production, as it can not be used as the only nitrogen source for tea fungus culture due to the low content of nitrogen in the leaves of the used plant.