Search Results (458)

Tea (Camellia sinensis L.) is a traditional plant and consumed as a beverage or medicinal drink. Camellia sinensis teas exhibit in vitro xanthine oxidase (XOD) inhibitory activity. The total phenols, total flavonoids, antioxidant capacity, and inhibitory effect on the XOD activity of 101 tea extracts were systematically analyzed. The total phenol content of green tea was 158.58 ± 4.15 mg gallic acid equivalents/g, and the total flavonoid content was 122.24 ± 4.17 mg rutin equivalents/g. The total phenol (75.36 ± 9.86 mg gallic acid equivalents/g) and flavonoid (62.95 ± 6.76 mg rutin equivalents/g) contents of dark tea were two-fold lower than those of green tea (p < 0.05). The antioxidant capacity of green tea was 494.32 ± 12.41, 434.88 ± 13.20, 614.99 ± 21.87, and 257.81 ± 8.56 mg Trolox equivalents/g as 1,1-diphenyl-2-picrylhydrazyl (DPPH), ferric ion reducing antioxidant power (FRAP), 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid(ABTS), and total reducing capacity, respectively. The antioxidant capacity of the dark tea group was the lowest. Black tea showed the numerically highest average XODi activity, while no significant difference in XODi activity was detected among green, yellow, and black teas (p > 0.05). The XOD inhibitory effect was positively correlated with total phenol, total flavonoid, and antioxidant capacities, revealing the relationship among tea polyphenols, antioxidant capacity, and XOD inhibition rate. Principal component analysis (PCA) and partial least square discriminant analysis (PLS-DA) showed that green tea had a strong antioxidant capacity and inhibitory effect on XOD. These findings provide an in vitro screening reference for tea resources with antioxidant and xanthine oxidase inhibitory activities, and further studies on key component identification and in vivo validation are warranted. Full article

Matcha, a finely milled powdered green tea originating from Japan, is characterized by a unique cultivation method in which tea plants are shaded prior to harvest. This practice enhances the accumulation of chlorophyll, caffeine, L-theanine, and other bioactive compounds. In addition, specialized post-harvest processing, including careful hand-picking, gentle steaming, drying, and traditional stone grinding, helps preserve the nutritional and biochemical integrity of the tea leaves. This review examines the relationship between cultivation and processing techniques and the resulting bioactive composition of matcha. It also summarizes current scientific evidence regarding the potential health-promoting properties of matcha and its major constituents. The analysis is based on available scientific literature, including both in vitro and in vivo studies investigating the biological activity of matcha and green tea catechins. Particular attention is given to studies evaluating their effects on metabolic parameters such as glucose levels, lipid profile, body weight regulation, and gut microbiota composition. In addition, the potential influence of matcha-derived compounds on neurological function, systemic physiological processes and anticancer potential is discussed. Furthermore, matcha is increasingly recognized as a functional food ingredient and has been incorporated into a variety of products, including bakery goods, dairy products, functional beverages, and nutraceutical formulations. The collected findings suggest that matcha may exert a broad spectrum of beneficial biological effects due to its high concentration of polyphenols, amino acids, and antioxidants. Nevertheless, despite promising experimental and preclinical data, further well-designed clinical studies are needed to better understand the mechanisms of action, bioavailability, and long-term health effects associated with regular matcha consumption. Full article

Green tea is highly popular due to its richness in polyphenols exhibiting broad bioactivities. Tea polyphenols, primarily catechins and flavonoids, demonstrate health benefits following biotransformation by the gut microbiota to overcome limited bioavailability. However, metabolites and interaction between green tea polyphenol and the gut microbiota remains to be fully elucidated. This study investigates the biotransformation of metabolites and interaction between human gut microbiota (HGM) and green tea extract (GTE) through in vitro anaerobic fermentation. Temporal bioactivity assessments demonstrated that fermentation-enhanced antioxidant capacity and inhibition potential of α-glucosidase, α-amylase and pancreatic lipase peak at 6 h, showing strong correlations with polyphenol and flavonoid biotransformation kinetics. Using the untargeted metabolomics approach, 55 characteristic differential compounds during the fermentation process in GTE were characterized, including 15 catechins, 29 flavonoids, five organic acids and six other phytochemicals. Furthermore, nine microbial-transformed metabolites derived from GTE flavonoids were identified and the corresponding metabolic pathways were proposed simultaneously. Analysis of 16S rRNA gene sequencing revealed that GTE significantly enhanced gut microbiota diversity and induced structural reorganization, specifically enriching genera such as Bacteroides, Bifidobacterium, Lactococcus and Enterococcus, which are likely involved in flavonoid biotransformation of GTE. Thus, the findings provide new insights for elucidating microbiota-mediated metabolites of green tea polyphenol, and their bidirectional interactions in the human gut. Full article

Quality deterioration, characterized by browning and cooked-off flavor (COF) development, often occurs in green tea beverages (GTBs) during shelf life. Changes in sensory quality and physical and chemical properties, as well as COF formation and its alleviation under different storage conditions, were comprehensively investigated in beverages prepared from five green teas and one jasmine-scented green tea. As the storage temperature increased and the storage duration extended, all GTBs exhibited a noticeable decrease in total sensory score (TSS), along with remarkable increases in total color difference (ΔE) and COF. Contents of total polyphenols declined markedly during storage of GTBs, while levels of caffeine and free amino acids changed insignificantly. Among the nine volatiles negatively correlated with TSS and positively correlated with COF, linalool, geraniol, 1-octanol, and 3-methylbutanal were identified as key COF contributors due to their high relative odor activity values. These results indicate that quality deterioration of GTBs during storage is closely associated with polyphenol loss, accumulation of COF-related components, and shifts in volatile composition and ratios. Notably, beverages prepared from jasmine-scented tea exhibited higher sensory scores and slower quality deterioration during storage than those prepared from unscented tea. This study identifies the key volatile contributors to COF and demonstrates that jasmine scenting effectively mitigates quality deterioration, offering a practical strategy for extending the shelf life of GTBs. Full article

Candida albicans (C. albicans) is an opportunistic fungal pathogen capable of causing a wide range of infections, including mucosal and systemic candidiasis. In the oral cavity, fungi represent a minor component of the microbiome but can significantly contribute to morbidity, particularly under conditions of dysbiosis or immunosuppression. Treatment remains challenging due to increasing multidrug resistance. This study investigates the in vitro antifungal potential of Viroelixir, a standardized polyphenol blend derived from green tea and pomegranate and enriched in catechins (including epigallocatechin gallate, EGCG), ellagitannins (notably punicalagin), ellagic acid, and flavonoids, with particular focus on its potential anti-virulence mechanisms. Methods: The effect of Viroelixir on C. albicans growth was assessed using MTT assay, optical density measurements, colony formation, carbohydrate quantification, and pH variation analysis. Biofilm formation, morphological transition, ROS production, necrosis, virulence gene expression, adhesion, and host immune responses were also evaluated. Results: Viroelixir significantly inhibited C. albicans growth and reduced colony formation compared with untreated controls. The formulation also inhibited biofilm formation and markedly reduced pseudohyphal development, reaching up to 94% reduction under specific treatment conditions. Flow cytometry analysis showed an increase in dead fungal cells, reaching approximately 88% following exposure to Viroelixir at the highest tested concentration. In addition, Viroelixir reduced the transcript levels of several virulence-associated genes, including SAP1–SAP9 and EAP1. In epithelial cell co-culture models, pre-treatment of C. albicans with Viroelixir reduced fungal adhesion and attenuated epithelial inflammatory responses, including IL-6, IL-8, and hBD-2 production, and was associated with reduced activation of the TLR4-NF-κB signaling pathway. Conclusions: These findings suggest that the antifungal and anti-virulence effects observed may be associated with the polyphenolic compounds present in the Viroelixir formulation, highlighting its potential as a promising in vitro antifungal candidate against C. albicans. Full article

To reveal how the characteristic flavor of jasmine tea is generated, this study analyzed the coordinated changes in sensory properties, chemical components, and aroma migration behavior during scenting. Sensory evaluation, biochemical assays, and headspace solid-phase microextraction–gas chromatography–mass spectrometry (HS-SPME-GC-MS) integrated with orthogonal partial least squares discriminant analysis (OPLS-DA) and relative odor activity value (rOAV) filtering were applied to tea samples before and after scenting. After scenting, aroma and taste scores increased significantly, and liquor color shifted from tender green to pale yellow. Amino acids and soluble sugars increased, while astringent substances such as tea polyphenols and catechins decreased. Key floral compounds, including cis-3-hexenyl benzoate and methyl anthranilate, were transferred from jasmine flowers to the tea base and enriched, likely contributing to the typical aroma profile. The retention rate of aroma in spent flowers was positively correlated with hydrophobicity (logP, r > 0.46, p < 0.01) and negatively with polarity (TPSA, r > −0.42, p < 0.05), suggesting regulation by hydrophobic partitioning. In contrast, aroma transfer to the tea base showed no simple correlation with any single physicochemical parameter, suggesting multi-factor regulation. This study provides insights into the scenting process and offers a theoretical reference for quality control in jasmine tea production. Full article

The herbal tea industry has experienced substantial growth, particularly regarding green tea (Camellia sinensis). In the manufacturing of filter tea, fine herbal dust is generated as a residual by-product during grinding and sieving and is typically discarded as waste. This study aims to explore the application of ultrasound-assisted extraction (UAE) for secondary valorisation of green tea herbal dust by investigating the effects of various parameters on extraction efficiency. Antiradical activity of UAE extracts was determined using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, and the total phenolic content (TPC) was measured using Folin–Ciocalteu’s assay. Furthermore, selected phenolics were quantified by HPLC and qualitatively characterised by liquid chromatography coupled with electrospray ionisation and quadrupole time-of-flight tandem mass spectrometry (LC-ESI-QToF-MS/MS). The results demonstrate that UAE parameters have a pronounced influence on the antioxidant activity, TPC, and individual polyphenolic profile of green tea herbal dust extracts. Ethanol–water mixtures at a ratio of around 40–60%, as well as moderate impulse regimes (around 60%) and extraction times (around 10 min), were the most suitable for extracting green tea polyphenols. Epigallocatechin gallate was the predominant phenolic component in most extracts, alongside epicatechin, epigallocatechin, catechin, and gallic acid. The findings highlight the UAE technique as a robust, green, and scalable method for valorising green tea by-products, thereby facilitating the development of high-value natural extracts for applications in the food, pharmaceutical, and cosmetic industries. Full article

Background/Objectives: Precocious puberty in girls currently appears to be one of the main problems in pediatric endocrine gynecology. Early onset of menstruation (EOM) means that the age at which the first menstruation occurs is lower than the average/median for the population, which ranges from 12 to 13 years and depends primarily on ethnic origin. Depending on age and severity of symptoms, these disorders negatively affect girls’ quality of life in many areas, including school life, family relationships, and everyday life. Methods: This article provides a scoping review summarizing scientific evidence from human studies on the association between substances derived from green tea (flavanols) and soy (isoflavones) and precocious puberty in girls. Results: Despite the relatively small number of girls enrolled in the studies, available scientific evidence from randomized controlled trials (RCTs) suggests that polyphenols from decaffeinated green tea (DGTP) may contribute to lowering the age of first menstruation in girls living with obesity. The effect of soy isoflavones or soy in the context of premature menstruation in girls is unclear. Most studies report that it may have no effect on the age of first menstruation, while individual studies suggest that very early exposure to soy (< 4 months of age) may result in earlier puberty, and others suggest that higher consumption of soy isoflavones delays this process. Conclusions: Further well-designed intervention studies in humans are needed to better understand the endocrine and metabolic relationships regarding the role and importance of specific polyphenols in the pathogenic mechanisms of the development and treatment of precocious puberty in girls. Full article

Quantum dots (QDs) have drawn a lot of attention as photocatalytic materials due to the growing need for environmentally friendly wastewater treatment technologies. Among these, carbon-based QDs, including graphene oxide quantum dots (GOQDs), graphitic carbon nitride (g-C₃N₄), and carbon quantum dots (CQDs), have exceptional optical, electronic, and surface characteristics that increase their suitability for degrading pollutants when exposed to sunlight or visible light. These composites are better at transferring charges, staying stable in light, and breaking down pollutants. Metal-based QDs like ZnO and CdS also have strong photocatalytic activity, but their sustainability remains a concern due to the potential release of toxic ions when they corrode in light. The green synthesis approach addresses these challenges. Using natural extracts, like polyphenols from tea leaves, to biofunctionalize surfaces has been shown to reduce toxicity and improve photocatalytic performance. Green synthesis using renewable precursors solves problems with toxicity, resource depletion, and environmental pollution, which supports a low-impact and circular technological approach. This study examines recent developments in the making, modifying, and use of QD-based photocatalysts in the environment, with a focus on CQD/g-C₃N₄ hybrid systems. Future research should focus on making green, non-toxic, regenerable, and highly active carbon-based QDs for safe large-scale water treatment. Full article

Rosehip-based products are rich in polyphenols with recognized health benefits, making accurate characterization essential for quality control and functional evaluation. Conventional analytical approaches for polyphenol determination are often time-consuming, costly, and environmentally demanding. In this study, a sustainable analytical method based on capillary zone electrophoresis coupled with diode array detection (CE–DAD) was developed as a green and accessible screening method for polyphenol analysis in rosehip-based products. Twelve polyphenolic compounds belonging to different classes (stilbenes, flavonols, flavanols, flavanones, and flavones) were used to optimize the electrophoretic conditions, including the buffer pH, voltage, and electrolyte concentration. Herbal tea and supplement samples were analyzed before and after a simple cartridge-based clean-up step to reduce matrix interferences. The method enabled simultaneous profiling of multiple polyphenol classes in a single CE–DAD run, showing excellent linearity (R² > 0.99), run to run reproducibility (RSD 0.8–1.6%), and sensitivity (LOD 0.4–1.4 μg/mL; LOQ 0.9–4.7 μg/mL). Eight target polyphenols were identified and quantified in real samples. Polyphenol profiling was complemented by DPPH and ABTS antioxidant assays, allowing a functional interpretation of compositional data and a case-based comparison between different product formulations. Specifically, the herbal tea showed the values of a 13.8 mg Trolox/g sample (80.5% DPPH inhibition) and 15.3 mg Trolox/g sample (98.5% ABTS inhibition), whereas the food supplement presented a 7.4 mg Trolox/g sample (34.2% DPPH inhibition) and 7.4 mg Trolox/g sample (54.1% ABTS inhibition). Method sustainability and applicability were also evaluated using the Blue Applicability Grade Index (BAGI), confirming a low environmental footprint. Full article

Background: Polyphenols—bioactive compounds abundant in plant-based foods—are increasingly recognised for their capacity to modulate the gut microbiota. As the gut microbiome plays a central role in metabolic regulation, immune function, and disease prevention, understanding how specific polyphenol subclasses influence microbial diversity and functionality remains essential. Despite growing evidence of their benefits, the precise effects of flavonoids, phenolic acids, and anthocyanins on gut microbial composition are not yet fully clarified. Objective: This study aimed to evaluate the impact of dietary polyphenols on gut microbiota composition and function, with a particular focus on the abundance of Bifidobacterium, a key beneficial genus associated with metabolic and immune health. It was hypothesised that polyphenol-rich interventions were associated with increases in Bifidobacterium abundance and enhance overall microbial diversity. Design: A systematic review and meta-analysis were conducted following PRISMA guidelines. Human intervention studies published between January 2015 and February 2025 were retrieved from PubMed, Scopus, and Web of Science. A predefined PICO framework guided study selection. Twenty-two studies were synthesised using thematic analysis, and four of these were eligible for quantitative meta-analysis. The meta-analysis was performed in R (version 4.4.1) using the metafor and meta packages, calculating standardised mean differences (SMD) under a random-effects model to account for heterogeneity. Extracted data included study design, population characteristics, polyphenol subclass, intervention type, microbiome assessment method, and key outcomes. Results: Across the 22 reviewed studies, polyphenols—particularly flavonoids and phenolic acids from foods such as berries, grape pomace, and green tea—consistently increased beneficial microbial taxa including Bifidobacterium, Faecalibacterium, and Lactobacillus. These microbial shifts were associated with improved metabolic markers, reduced inflammation, and enhancements in gut barrier integrity. Polyphenol-rich dietary patterns also showed benefits in conditions such as NAFLD, prediabetes, and depression. However, findings were influenced by interindividual variability, short intervention durations, and inconsistent methodologies. The meta-analysis revealed a significant positive effect of polyphenol intake on Bifidobacterium abundance (SMD = 0.81; 95% CI: 0.18–1.44; p = 0.0114), corresponding to a moderate-to-large effect size. Substantial heterogeneity (I² = 77.4%) suggested considerable variation in intervention types, dosage, study design, and microbiome analysis methods. Conclusions: Polyphenol-rich diets were associated with increased Bifidobacterium abundance and favourable modulation of gut microbiota composition, supporting their potential as a nutritional strategy to enhance gut and metabolic health. However, interstudy variability highlights the need for more standardised, long-term, and mechanistically focused human trials. Future research should incorporate multi-omics approaches, personalised nutrition frameworks, and consistent microbiome analysis methods to better understand the pathways linking polyphenol intake and host health outcomes. Full article

Shiqian Taicha (Camellia sinensis) is a local tea cultivar originating from Shiqian County and Guizhou (China) that is suitable for both green and black tea. The year-on-year manufacturing conditions, which affect chemical quality, were elucidated through the analysis of 78 green tea and 38 black tea commercial batches manufactured in 2021–2023. The batches were manufactured by the same process, but these naturally varied in raw-leaf status and factory parameters. The moisture content, water-soluble extract, free amino acids, tea polyphenols, caffeine, gallic acid, total ash, total catechins and individual catechins were predicted using a calibrated near-infrared (NIR) spectroscopy model and membership function evaluation, which integrated multiple indices to produce an overall quality score for each year and tea type. The amino acids of green tea peaked in the year 2022, (with 4.55%) whereas the polyphenols (which refers to carbon-based molecules) was in the year 2021, (with 24.22%), and the total catechins was in the year 2021, (with 16.71%); due to these observations, the ratio of phenol-to-amino was high in the year 2021, with (10.09); while the year 2022 had a lower ratio with (3.41). Although there were fewer differences from region to region with black tea, 2022 was better in terms of moisture control, amino acids retention and composite score with a value of 0.585. The assessment of the membership function indicated that 2022 was the most ideal tea production year for green tea (0.506) as well as black tea (0.477), with 2021 tea (0.486) and 2023 tea (0.488) following next based on type. The data presents quantitatively stable fixation and moisture/fermentation management targets to improve Shiqian Taicha value and consistency. Full article

The contents of biochemical components, such as theanine, tea polyphenols, water extract, and soluble sugar in Hakka stir-fried green tea (HSGT), serve as important indicators reflecting the intrinsic quality of tea leaves. In this study, 171 HSGT samples are collected, and their near-infrared spectroscopy (NIRS), together with the contents of the four indicators, are determined. The aim is to establish prediction models for these four indicators by extracting multiple features from the NIRS data. First, the NIRS data is preprocessed. Then, multiple features are extracted using competitive adaptive reweighted sampling (CARS), adaptive Fourier decomposition (AFD), fast Fourier transform (FFT), continuous wavelet transform (CWT), and band combination (BC). Finally, ridge regression (RR) and partial least squares regression (PLSR) models are constructed based on the NIRS features to predict the four indicators. Experimental results show that the model combining multiple features, namely CARS + AFD + BC, delivers the best overall performance. Specifically, the RR model based on multiple features provides the most accurate predictions for theanine, tea polyphenols, and soluble sugar, while the PLSR model performs better for water extract. This study provides a rapid and accurate method for detecting the substance content in HSGT. Full article

Epigallocatechin-3-gallate (EGCG), the major bioactive polyphenol in green tea, has garnered significant attention for its potential anticancer properties. This review summarizes the current evidence from in vitro, in vivo, and clinical trials examining the effects of EGCG on lung cancer. EGCG exerts its anticancer effects through various mechanisms, including the inhibition of cell proliferation, induction of apoptosis, suppression of metastasis, and modulation of signalling pathways such as epidermal growth factor receptor (EGFR), phosphoinositide 3-kinase/protein kinase B (PI3K/Akt), mitogen-activated protein kinase (MAPK), and nuclear factor kappa B (NF-κB). Additionally, EGCG has been shown to enhance the efficacy of conventional chemotherapeutic agents and mitigate drug resistance. However, challenges related to its bioavailability and metabolic stability remain. Ultimately, this review aims to provide a comprehensive overview of the effects of EGCG against lung cancer. Full article

Tea production in Europe represents an emerging segment of the specialty tea market, but a structured comparative analysis remains unexplored. This study employs a standardized approach to systematically characterize hot brews from black and green teas across five European gardens. Antioxidant capacity, total polyphenolic content (TPC), total flavonoid content (TFC), and metabolomic profiling by ultra-high performance liquid chromatography–mass spectrometry were evaluated, and for the first time, sensory profiling of these teas was conducted. Green teas consistently exhibited higher TPC, TFC, and antioxidant capacity compared to black teas, confirming the influence of processing methods. Metabolomic analysis revealed variability in caffeine linked to geographical origin and propagation method (cuttings vs. seeds). Importantly, sensory evaluation suggested a negative correlation between high TPC and overall consumer appreciation. The two most highly appreciated teas often showed lower TPC. These reliable findings advance knowledge in European tea research, providing valuable data for growers to enhance cultivar selection and marketing strategies in alignment with consumer preferences. Full article