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

a r t i c l e i n f o 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 en-teric 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. Dark teas, such as pu'er and fuzhuan, are produced by fungal fermentation of Camellia sinensis L. (Theaceae) leaves (Xu et al., 2011). Fuzhuan tea, native to the Hunan province of China, is consumed as an ethno-botanical remedy for treating food-borne illnesses, dysentery , and aiding general nutrition and digestion (Fu et al. Fuzhuan tea has been shown to stimulate pancreatic amylase and protease in vitro (Yu, 2009) and inhibit the growth of food-borne pathogens Ba-cillus cereus, Bacillus subtilis, Clostridium perfringens, and Clostridium sporogenes (Mo, Zhu, & Chen, 2008), providing evidence for digestive and intestinal health protective actions. Several reports suggest that the fermentation process results in a final product with a unique phytochemical profile compared to other types of tea. Targeted analysis of catechins, commonly associated with the antioxidant and cancer fighting properties of green tea, showed their in fuzhuan tea following fermentation (Wu et al., 2010). Several organic acids, including oxalic, α-keto-glutaric, L-malic, succinic and ascorbic acid were also decreased by fermentation. However, organic acids such as lactic, acetic, and citric acids, which are fermentation products of beneficial lactic acid bacteria, increased with fuzhuan tea fermentation (Wu et al., 2010). Taken together, this suggests that fuzhuan tea has a unique phytochemical profile that is, in part, due to the microbial fermentation employed during its production. As fuzhuan tea is produced by microbial fermentation of …