Green Synthesis, Characterization and In Vivo Evaluation of White Tea Silver Nanoparticles with 5-Fluorouracil on Colorectal Cancer

Investigations of the highly efficient processing technique, chemical constituents, and anti-inflammatory effect of N-ethyl-2-pyrrolidinone-substituted flavan-3-ol (EPSF)-enriched white tea

N-Ethyl-2-pyrrolidinone-substituted flavan-3-ols (EPSFs) are a newly discovered compound class in tea with various bioactivities. This study aimed to develop a novel processing technique to enhance EPSF contents in white tea efficiently. Using optimal processing parameters of 125 °C and 30 min in a high-temperature sterilizing oven, total EPSF content significantly increased by 1.42-18.80-fold to 1.57-6.22 mg/g without impacting sensory characteristics. Metabolomics analysis revealed elevated levels of nucleosides, nucleotides, bases, theaflavins, flavonol aglycones, EPSFs, and most flavone-C-glycosides, as well as decreased levels of amino acids, procyanidins, theasinensins, several flavanols, and flavonol-O-glycosides after EPSF-enrichment treatment. Furthermore, the EPSF-enriched white tea exhibited notable anti-inflammatory effects, mitigating xylene-induced ear edema in mice and carrageenan-induced paw edema and cotton ball-induced granulomas in rats. This study developed a new processing technique for highly efficient enhancement of EPSFs in white tea and demonstrated that EPSF-enriched white tea has a potential to serve as effective anti-inflammatory dietary supplement.

Metabolomics investigation of the chemical variations in white teas with different producing areas and storage durations

In this study, we employed nontargeted metabolomics and quantitative analysis to explore the variations in metabolites among white teas from different production areas and with varying storage durations. A total of 83 compounds exhibited differential levels between Zhenghe and Fuding white tea, 89 between Zhenghe and Jinggu, and 75 between Fuding and Jinggu white tea. Concerning the storage of white tea, the concentrations of flavanols, dimeric catechins, and amino acids decreased over time, while N-ethyl-2-pyrrolidone-substituted flavanols (EPSFs), caffeine, adenosine monophosphate (AMP), and adenosine increased. Galloylated flavanols showed a higher propensity to form EPSFs with theanine compared to nongalloylated flavanols during storage. Theanine and epigallocatechin gallate were more inclined to generate S-configuration EPSFs during storage in Fuding and Jinggu white tea samples, while R-configuration EPSFs were more readily formed in Zhenghe white tea samples. This study offers a comprehensive understanding of the changes in metabolites during the storage of white tea.

Nano-Strategies for Enhancing the Bioavailability of Tea Polyphenols: Preparation, Applications, and Challenges

Tea polyphenols (TPs) are among the most abundant functional compounds in tea. They exhibit strong antioxidant, anti-inflammatory, and anti-cancer effects. However, their instability and low bioavailability limits their applications. Nanotechnology, which involves the use of nanoscale substances (sizes ranging from 1 to 100 nm) to improve the properties of substances, provides a solution for enhancing the stability and bioavailability of TPs. We reviewed the preparation, performance, effects, and applications of different types of TPs nanocarriers. First, we introduced the preparation of different nanocarriers, including nanoparticles, nanoemulsions, nanomicelles, and nanolipids. Then, we discussed various applications of tea polyphenol-loaded nanocarriers in functional ingredient delivery, food quality improvement, and active food packaging. Finally, the challenges and future development directions of TPs nanocarriers were elucidated. In conclusion, a nano-strategy may be the “key” to break the application barriers of TPs. Therefore, the use of nano-strategies for the safe, stable, and efficient release of TPs is the direction of future research.