Antibacterial activity and phytochemical profile of fermented Camellia sinensis (fuzhuan tea)

Fuzhuan tea is a traditional preparation of Camellia sinensis L. (Theaceae) from Hunan, China, that is fermented with the fungus Eurotium cristatum. Metabolomic analysis was performed on fuzhuan tea extracts and compared to extracts of non-fermented green teas using ultra-performance liquid chromatography/time of flight-mass spectrometry (UPLC-ToF-MS). Principal component analysis revealed a unique phytochemical profile between the two types of tea with the largest separation visible along the third principle component, which accounted for 12.4% of dataset variation. Spectral comparison of significantly different tea metabolite features allowed tentative identification of flavonoids including catechins, fatty acid amides, and other lipids and polysaccharides. Fuzhuan tea extracts, at a concentration of 5 mg/mL or less, reduced the growth of enteric pathogens Shigella sonnei and Staphylococcus aureus by 50%, and had a minimum inhibitory concentration (MIC) of 0.625 mg/mL against S. aureus. These results support a distinct phytochemical profile associated with fermented fuzhuan tea compared to non-fermented green teas that warrant further investigation for novel compounds with antimicrobial bioactivity.