Chemical characterization and bioactivity of phenolics from Tieguanyin oolong tea

Abstract

Phenolics are the main bioactive components in tea and greatly contribute to human health. Three phenolic‐enriched extracts, the ethyl acetate fraction (TEF), n‐butanol fraction (TBF), and water fraction (TWF), were obtained from Tieguanyin oolong tea, which is considered a typical type of semi‐fermented tea. The chemicals in the extracts and their antioxidant activity and cytotoxicity against 4T1 breast cancer cells were investigated in the present work. TEF was found to have the highest contents of phenolics, flavonoids, procyanidins, sugars, and catechin monomers. Meanwhile, TEF exhibited the strongest antioxidant capacity, which may be due to its abundant bioactive compounds, as validated by Pearson correlation and hierarchical clustering analysis. Furthermore, TEF showed greater inhibition of the growth of 4T1 murine breast cancer cells than TBF and TWF. Practical applications Fermentation during the processing of oolong tea causes many alterations in polyphenols, leading to different bioactivities. In the present work, three phenolic‐enriched extracts, the ethyl acetate fraction (TEF), n‐butanol fraction (TBF), and water fraction (TWF), were obtained from Tieguanyin oolong tea. Further tests showed that TEF and TBF from Tieguanyin oolong tea possessed remarkable antioxidant activity and inhibitory potential inhibition of the growth of 4T1 murine breast cancer cells in vitro due to their main bioactive compounds, including phenolics and flavonoids. Thus, the phenolic‐enriched extracts from Tieguanyin tea are expected to have a potential application in the food and pharmaceutical industries after further study.

Untargeted Metabolomics and Transcriptomics Reveal the Mechanism of Metabolite Differences in Spring Tender Shoots of Tea Plants of Different Ages

“…Tea polyphenols, also known as tea tannins, mainly include catechins, flavonoids, anthocyanidins, phenolic acid, and depsides [ 37 ]. Free amino acids in tea include protein amino acids and non-protein amino acids [ 38 ].…”

Effects of the Baking Process on the Chemical Composition, Sensory Quality, and Bioactivity of Tieguanyin Oolong Tea

“…The ABTS, DPPH, and hydroxyl radical scavenging activities of BT2 were significantly reduced compared with BT0 ( Figures 3A–C ). Earlier researches suggested that the ethyl acetate fraction of TOT, which had higher contents of phenolics, flavonoids, procyanidins, sugars, and catechin monomers, exhibited stronger antioxidant capacity than the n-butanol fraction and water fraction of TOT ( 36 ). Su et al demonstrated that monomeric catechins played critical roles in anti-oxidation ( 37 ).…”

Comparison of Phenolic Contents and Scavenging Activities of Miang Extracts Derived from Filamentous and Non-Filamentous Fungi-Based Fermentation Processes

“…The increase in TP (~2-fold and 1.38-fold for NFP-Miang and FFP-Miang) and TT (~2-fold and 1.80fold, respectively) could be attributed to microbial hydrolytic enzymes (such as esterases and glucosidases) capable of lysing complex phenolics, thereby releasing free absorbable phenolic compounds that are easily detected [26]. Other reasons for this increase might include an increase in the extractability of tea polyphenols and microbial biosynthetic and/or hydrolytic enzymes (such as amylases, proteases, and xylanases) capable of causing structural modification of tea leaf cell walls during fermentation, thus mobilizing free polyphenols from complexed forms or synthesizing new bioactive phenolics from the available substrates [27][28][29]. The contents of CT also significantly increased (p < 0.05) after fermentation (NFP-Miang: 198.36 mg/g and FFP-Miang: 170.04 mg/g) compared to their respective starting materials (young leaves: 43.12 mg/g and mature leaves: 27.01 mg/g).…”