Antibacterial Activity of Polyphenolic Fraction of Kombucha Against Enteric Bacterial Pathogens
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The emergence of multi-drug-resistant enteric pathogens has prompted the scientist community to explore the therapeutic potentials of traditional foods and beverages. The present study was undertaken to investigate the efficacy of Kombucha, a fermented beverage of sugared black tea, against enterotoxigenic Escherichia coli, Vibrio cholerae, Shigella flexneri and Salmonella Typhimurium followed by the identification of the antibacterial components present in Kombucha. The antibacterial activity was evaluated by determining the inhibition zone diameter, minimal inhibitory concentration and minimal bactericidal concentration. Kombucha fermented for 14 days showed maximum activity against the bacterial strains. Its ethyl acetate extract was found to be the most effective upon sequential solvent extraction of the 14-day Kombucha. This potent ethyl acetate extract was then subjected to thin layer chromatography for further purification of antibacterial ingredients which led to the isolation of an active polyphenolic fraction. Catechin and isorhamnetin were detected as the major antibacterial compounds present in this polyphenolic fraction of Kombucha by High Performance Liquid Chromatography. Catechin, one of the primary antibacterial polyphenols in tea was also found to be present in Kombucha. But isorhamnetin is not reported to be present in tea, which may thereby suggest the role of fermentation process of black tea for its production in Kombucha. To the best of our knowledge, this is the first report on the presence of isorhamnetin in Kombucha. The overall study suggests that Kombucha can be used as a potent antibacterial agent against entero-pathogenic bacterial infections, which mainly is attributed to its polyphenolic content.
KeywordsHigh Performance Liquid Chromatography Minimal Inhibitory Concentration Catechin Ethyl Acetate Extract Minimal Bactericidal Concentration
We thank Dr. Joydeep Mukherjee, UGC Associate Professor and Dr. Sayani Mitra, Mr. Kaushik Biswas and Mr. Sayak Bhattacharya of School of Environmental Studies, Jadavpur University, Kolkata for HPLC analysis and Prof. Mahammad Ali, Department of Chemistry, Jadavpur University, Kolkata for ESI–MS study. We also thank Dr. Saubhik Haldar of Department of Chemistry, Jadavpur University, Kolkata for analysis of the sample and Dr. Dhrubajyoti Nag, Dr. Ritam Sinha and Ms. Priyadarshini Mukherjee of National Institute of Cholera and Enteric Diseases, Kolkata for efficient assistance in the study. This work has been financially assisted by the Department of Science and Technology, Government of India.
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Conflict of interest
The authors declare that they have no conflict of interest.
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