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Metabolic syndrome (MetS) is a group of abnormal disorders; hypertension, glucose intolerance, dyslipidemia, proinflammatory, and prothrombotic states, affecting approximately 14 % of the world's population. The potential of grape seeds extract (GSE) supplementation to improve the metabolic disturbances and their related conditions like obesity, type 2 diabetes, and nonalcoholic fatty liver disease was investigated in this study. In-vitro metabolic syndrome assays were investigated through α-amylase, α-glucosidase, lipase, lipoxygenase (LOX), cyclooxygenases (COX-1 and COX-2), renin and angiotensin converting enzyme (ACE) inhibition assays. Additionally, in-vivo rat model of high-fat-high-carbohydrate diet (HFD)-induced MetS was established, where metformin (MT) (200 mg/kg) was used as a reference drug and GSE was given at 100 and 200 mg/kg by oral gavage. GSE was standardized using HPLC analysis for the major reported compound; catechin which should be ≥ 160.76 ± 5.52 μg/mL. Total phenolic content of GSE was 21.12±0.61 µg gallic acid equivalent/1 mg extract and total flavonoid content was 23.81±0.64 µg rutin equivalent/1 mg extract. In-vitro assays revealed the potential of GSE to manage the metabolic syndrome, besides its strong antioxidant capacity. Treatment with GSE (100 mg/kg and 200 mg/kg) markedly (P < 0.05) controlled the weight gain, improved the metabolic pathways (total glucose, cholesterol, triglycerides, AST, and ALT), oxidative stress parameters (MDA, GSH, and catalase) and inflammatory biomarkers in HFD fed rats. GSE downregulated the expression of insulin resistance gene (IR) and some inflammatory related genes (TNF-α and NF-κB), additionally it improved the pathological features of metabolic conditions and upgraded the expression of Nrf2 compared to HFD group. The superior effects were owned to the high dose of GSE, 200 mg/kg b.wt. (P < 0.05, P < 0.001). All results sustenance the beneficial effects of the standardized GSE in the management of metabolic syndrome. [Display omitted] • Grapes (Vitis vinifera L.) as a medicine have been well known since ancient times. • Inhibition assays documented GSE in the management of the metabolic syndrome. • GSE had hypoglycemic, hypolipidemic, hepatoprotective, and anti-inflammatory. • GSE improved the pathological features of metabolic conditions. • Standardization of GSE using HPLC, catechin should be ≥ 160.76 ± 5.52 μg/mL. [ABSTRACT FROM AUTHOR]

While catechins have been reported to exhibit potential to benefit osteoporosis patients, the effects of planar catechin (PCat), synthesized during the development of drugs for Alzheimer's disease, have not been clearly elucidated. Here, we examined the effects of PCat on mouse bone metabolism both in vivo and in vitro. Six week old female mice were orally administered PCat (30 mg/kg) every other day for four weeks, and their femurs were analyzed using micro-computed tomography imaging. Osteoclasts and osteoblasts were collected from mice and cultured with PCat. Subsequently, osteoclast formation and differentiation and osteoblast differentiation were observed. Mice orally administered PCat displayed significantly increased femur bone mass compared to the control group. Quantitative polymerase chain reaction findings indicated that PCat addition to osteoclast progenitor cultures suppressed osteoclast formation and decreased osteoclast marker expression without affecting the proliferative potential of the osteoclast progenitor cells. Addition of PCat to osteoblast cultures increased osteoblast marker expression. PCat inhibits osteoclast differentiation and promotes osteoblast differentiation, resulting in increased bone mass in mice. These results suggest that PCat administration is a promising treatment option for conditions associated with bone loss, including osteoporosis. [ABSTRACT FROM AUTHOR]

A hyperinflammatory condition is brought on by the development of Coronavirus disease 2019 (COVID-19), which is characterized by an elevation of T helper (Th) 17 cells, high levels of pro-inflammatory cytokines, and a depletion of regulatory T (Treg) cells. In this research, we examined the effect of nano-curcumin and catechin on the TCD4+, TCD8+, Th17, and Treg cells and their associated factors in COVID-19 patients. For this purpose, 160 (50 patients excluded during the study) COVID-19 patients were divided into four groups: placebo, nano-curcumin, catechin, and nano-curcumin + catechin. The frequency of TCD4+, TCD8+, Th17, and Treg cells, the gene expression of transcription factors (STAT3, RORt, and FoxP3) relevant to Th17 and Treg, as well as the serum levels of cytokines (IL-6, IL17, IL1-b, IL-10, and TGF-), were all evaluated intra- and inter-group, before and after treatment, in all groups. Our study showed that TCD4 + and TCD8 + cells were significantly higher in the nano-curcumin + catechin group compared to the control group, whereas Th17 was lower than the initial value. Furthermore, compared to the placebo-received group, cytokines and transcription factors associated with Th17 were significantly lower in the nano-curcumin + catechin group. Additionally, combined therapy increased Treg cells and transcription factors compared to the placebo group. Overall, our results show that combining nano-curcumin with catechin has a more notable impact on the enhancement of TCD4+, TCD8+, and Treg cells, as well as a decrease in Th17 cells and their mediators, suggesting a promising combination therapy in reducing the inflammatory conditions of COVID-19 infected patients. [ABSTRACT FROM AUTHOR]

• The ethanolic extract was prepared from the leaves of P. insignis. • GC-MS analysis performed on the ethanolic extract of P. insignis leaves revealed the presence of 60 phytocompounds. • HPLC analysis identified the flavonoid catechin which justifies the anti-inflammatory effect of P. insignis in the treatment of acute respiratory distress syndrome. Platonia insignis Mart., popularly known as bacuri, is a plant in which all its parts are indicated for use in folk medicine. The decoction of the seeds, for example, is used to treat diarrhea, while the oil from the seeds is used to treat skin diseases, otitis, rheumatism, arthritis, and cicatrization. The objective of this work was to perform a phytochemical analysis of the ethanolic extract of P. insignis leaves and to evaluate the pharmacological action of the extract on acute respiratory distress syndrome (ARDS) by intestinal ischemia and reperfusion in rats. For the induction of ARDS, male rats were distributed into seven groups. The negative control group was submitted to ischemia and reperfusion but was not treated. The test groups were treated by inhalation with ethanolic extract of freeze-dried P. insignis leaves (500 mg/kg) and associations. Lung structural and inflammatory changes were evaluated by histological examination. The preliminary phytochemical screening found that the leaf extract contained alkaloids, saponins, and triterpenes. The GCMS– analysis verified that the extract presented 60 compounds, in which phytol (10.54%), gamma-sitosterol (9.88%), and hexadecanoic acid (9.84%) were the major compounds identified. Analysis by CLAE revealed the secondary metabolite catechin in the extract. Finally, the extract was able to stagnate the marked dilation of terminal and respiratory bronchioles and alveoli. The results suggest that the ethanolic extract of P. insignis leaves is a promising therapeutic option to treat ARDS. [ABSTRACT FROM AUTHOR]

• Turkey tail polysaccharide was isolated from turkey tail and characterized by FT-IR and 1H NMR spectra. • A novel turkey tail polysaccharide-folic acid magnetic nanoparticles was synthesized for targeted delivery of catechin. • Catechin loaded synthesized MNPs showed antioxidant effect. • Turkey tail polysaccharide-folic acid magnetic nanoparticles and catechin loaded synthesized MNPs showed potent cytotoxicity against MCF-7. A magnetic nanocarrier was successfully prepared with Fe 3 O 4 magnetic nanoparticles (MNPs), turkey tail polysaccharide and folic acid and then catechin was loaded on this carrier. Radical scavenging activity of catechin loaded MNPs was evaluated via DPPH method (IC50: 1.41 mg/mL). Synthesized Fe 3 O 4 MNPs is hemocompatible with negligible hemolytic effects. The results of cytotoxic effects of synthesized MNPs toward normal fibroblast cells clearly demonstrate that the catechin loaded MNPs were safe and biocompatible. Furthermore, the anticancer activity on MCF-7 cancer cells was indicated by MTT test. The results demonstrated that prepared MNPs have the cytotoxic effects toward MCF-7 comparison with normal fibroblast cell lines. [ABSTRACT FROM AUTHOR]

• MWCNTs application in vitro increased the proliferation of callus biomass in Thymus daenensis. • Using MWCNTs has caused the plant tissues to accumulate secondary metabolites including rosmarinic acid, ferulic acid, caffeic acid, catechin, vanilin and hesperedin. • Transmission electron microscopy revealed carbon nanotubes in contact with the cell walls. • Findings report how plants respond phytochemically and physiologically to MWCNTs. Carbon nanotubes (CNTs) as novel promising nanomaterials have attracted considerable interest with excellent potential to boost the production of bioactive substance in plants. In the present study, we assessed morphological, physiological and phytochemical properties of Thymus daenensis callus culture upon exposure to various concentrations of multi-walled CNTs (MWCNTs) in vitro. Aseptic explants were cultured on 2, 4-dichlorophenoxy acetic acid (2, 4-D) and benzyl amino purine (BAP) containing Murashige and Skoog (MS) media. Results showed that callus exposure to MWCNTs may stimulate cells to absorb more water, grow faster and ultimately assist T. daenensis callus in accumulating higher fresh and dry biomass (maximum 100 µg ml−1). The application of MWCNTs resulted in higher values of antioxidant capacity, total flavonoids and phenolic compounds. High-Performance Liquid Chromatography (HPLC) analysis revealed that MWCNTs at specific concentration stimulate rosmarinic acid (25.25 mg g−1 DW), ferulic acid (1.97 mg g−1 DW), caffeic acid (1.02 mg g−1 DW), catechin (1.99 mg g−1 DW), vanilin (0.91 mg g−1 DW) and hesperedin (2.83 mg g−1 DW) biosynthesis. This increase followed a dose-dependent manner and was associated with changes in phenylalanine ammonia lyase enzyme activity (PAL). Maximum levels of antioxidant enzymes were obtained in callus grown on MS media supplemented with 500 and 1000 µg ml−1 of MWCNTs. Transmission electron microscopy (TEM) and optical microscopy micrographs revealed that MWCNTs entered the cell wall, cytoplasm and chloroplast, thereby increasing the cell size through mechanisms of action. The results revealed that MWCNTs can cross cell walls, enter the cytoplasm and other cellular organelles and facilitate water absorption. More biomass production and antioxidant biosynthesis were associated with higher levels of secondary metabolite production. Overall, the results indicated that MWCNTs can be used as a valuable elicitor in vitro for producing the highest economic values of rosmarinic acid, ferulic acid, caffeic acid, catechin, vanilin and hesperedin for pharmaceutical, therapeutic and food purposes. [ABSTRACT FROM AUTHOR]

Thearubigins (TRs) is a type of heterogeneous mixture from black tea, usually accounts for 60–70% of dry substance of black tea infusion. It is an important tea pigment for food industry and also contributes much to the sensory properties and biological activities of black tea. TRs therefore have a practical application value for the development of tea processing, natural food colorants and healthy products. The review paper summarizes the current knowledge from the perspectives of formation mechanism, chemical structure, sensory characteristics and health benefits of TRs. Through the oxidation mechanism and products of flavan-3-ols, the primary characteristics and reaction pathways of catechin, gallocatechin and galloylated catechin are profiled. Furthermore, the sensory properties and biological activities of TRs are comprehensively discussed. Gallocatechins containing vic -trihydroxy are more liable to lose protons and produce o -quinone, and subsequently condense through B–B ring to form dehydrotheasinensin, theasinensin, dehydrotheasinensin AQ in a pathway, or form bicyclo[3.2.1]octane to produce theacitrins, theacitrinins and proepitheaflagallin in another pathway. Furthermore, the oxidation of a couple of catechol- and pyrogallol-type catechins produce theaflavins (TFs), theanaphthoquinone and theanaphththeaflavins. Catechin can undergo nucleophilic reaction to form polymers, while catechin gallate also forms polymers through condensing consecutive benzotropolone moieties. The ratio of TRs to TFs is a critical index for color and brightness of black tea infusion, thus regulating enzymatic oxidation of tea polyphenols is not only an effective strategy in high-quality black tea processing, but also provides more options for tea pigment producing in beverage industry. • Formation mechanism of thearubigins is profiled. • Basic units of thearubigins are clarified. • Thearubigins health benefits are discussed. • Sensory properties of thearubigins are proposed. [ABSTRACT FROM AUTHOR]

Transmissible spongiform encephalopathies (TSEs) or prion diseases are fatal neurodegenerative diseases with no approved therapeutics. TSE pathology is characterized by abnormal accumulation of amyloidogenic and infectious prion protein conformers (PrPSc) in the central nervous system. Herein, we examined the role of gallate group in green tea catechins in modulating the aggregation of human prion protein (HuPrP) using two green tea constituents i.e., epicatechin 3-gallate (EC3G; with intact gallate ring) and epigallocatechin (EGC; without gallate ring). Molecular docking indicated distinct differences in hydrogen bonding and hydrophobic interactions of EC3G and EGC at the β2-α2 loop of HuPrP. These differences were substantiated by 44-fold higher KD for EC3G as compared to EGC with the former significantly reducing Thioflavin T (ThT) binding aggregates of HuPrP. Conformational alterations in HuPrP aggregates were validated by particle sizing, AFM analysis and A11 and OC conformational antibodies. As compared to EGC, EC3G showed relatively higher reduction in toxicity and cellular internalization of HuPrP oligomers in Neuro-2a cells. Additionally, EC3G also displayed higher fibril disaggregating properties as observed by ThT kinetics and electron microscopy. Our observations were supported by molecular dynamics (MD) simulations that showed markedly reduced α2-α3 and β2-α2 loop mobilities in presence of EC3G that may lead to constriction of HuPrP conformational space with lowered β-sheet conversion. In totality, gallate moiety of catechins play key role in modulating HuPrP aggregation, and toxicity and could be a new structural motif for designing therapeutics against prion diseases and other neurodegenerative disorders. [ABSTRACT FROM AUTHOR]

Abies species are known to have various bioactive compounds and pharmacological activities. In the manuscript, their bioactive components and anticancer activities of four unexamined Abies in Anatolia (Abies cilicica subsp. isaurica, Abies nordmanniana subsp. nordmanniana, Abies nordmanniana subsp. bornmuelleriana, Abies nordmanniana subsp. equi-trojani) were investigated. The principal component analysis and drug likeness properties of the specific bioactive compounds were conducted on our datas. The results showed that solvent polarity affected the phytochemical composition of extracts and thus their anticancer activity. Gentisic acid, catechin, palmitic acid, stearic acid, oleic acid, caryophyllene, caryophyllene oxide and eicosene were identified as major components. The principal component analysis of the specific bioactive compounds results indicated that the compounds are able to have an effective anticancer activity against HeLa an C6 cells. At the same time, the drug likeness properties results showed that these compounds have a potential drug properties. Also, docking result demonstrated that oleic acid, stearic acid, catechin, palmitic acid and eicosene can perform a strong synergistic effect against Cyclooxygenase-2 activity. Hovewer, oleic acid had the best binding poses against six targets. According to the findings, this four Abies species could be considered for further phytopharmaceutical researchs. [Display omitted] • The four Abies species from Turkey were researched. • GC–MS and HPLC-TOF/MS were used to determine phytochemicals of the extracts. • Abies ssp.'s anticancer effects against C6 and Hela cells were evaluated. • Molecular dockings showed interactions of anticancer effects and phytochemicals. • Abies ssp. could be considered for further pharmaceutical researchs. [ABSTRACT FROM AUTHOR]

In this study, four dialdehyde starch-catechin (DAS-catechin) conjugates were prepared by conjugating (-)-epicatechin (EC), (-)-epigallocatechin (EGC), (-)-epicatechin gallate (ECG) and (-)-epigallocatechin gallate (EGCG) with dialdehyde starch. Then, DAS-catechin conjugates were used as antioxidant and cross-linking agents to produce chitosan (CS) based antioxidant packaging films. The functionality of CS/DAS-catechin conjugate films was determined. Results showed four DAS-catechin conjugates formed Schiff-base linkages and hydrogen bond interactions with CS, resulting in improved film uniformity. Compared with plain CS film, CS/DAS-catechin conjugate films owned higher UV–vis light, water vapor and oxygen barrier ability, lower swelling degree, and stronger tensile strength, thermal stability and antioxidant activity. The cross-linking between CS and DAS-catechin conjugates delayed the biodegradable process of CS film. CS/DAS-catechin conjugate films showed good performance on inhibiting sunflower seed oil oxidation. Notably, CS/DAS-ECG conjugate film had the highest oxygen barrier, mechanical and antioxidant performances among four CS/DAS-catechin conjugate films. Therefore, CS/DAS-ECG conjugate film is an antioxidant packaging candidate for edible oil. • Chitosan film was cross-linked by dialdehyde starch-catechin conjugates. • Conjugates formed Schiff-base linkages and hydrogen bonds with chitosan. • Conjugates elevated the barrier, mechanical and antioxidant properties of film. • Film with dialdehyde starch-epicatechin gallate conjugate had the best performance. [ABSTRACT FROM AUTHOR]

A novel encapsulation system was designed, utilizing sodium alginate (SA) polysaccharide as the matrix and easily absorbed Fe2+ as the metal-organic framework, to construct microbead scaffolds with both high catechins (CA) and vitamin C (Vc) loading and antioxidant properties. The structure of microbead hydrocolloids was investigated using SEM, XPS, FTIR, XRD and thermogravimetry, and the antioxidant activity, in vitro digestion and the release of CA and Vc were evaluated. These results revealed that the microbead hydrocolloids SA-CA-Fe and SA-CA-Vc-Fe exhibited denser and stronger cross-linking structures, and the formation of inter- and intramolecular hydrogen and coordination bonds improved thermal stability. Moreover, SA-CA-Fe (44.9 % DPPH and 47.8 % ABTS) and SA-CA-Vc-Fe (89.9 % DPPH and 89.3 % ABTS) displayed strong antioxidant activity. Importantly, they were non-toxic in Caco2 cells. The SA-CA-Fe and SA-CA-Vc-Fe achieved significantly higher CA (56.9 and 62.7 %, respectively) and Vc (42.2 %) encapsulation efficiency while maintaining higher CA and Vc release in small intestinal environment. These results suggested that SA polysaccharide-based encapsulation system using Fe2+ framework as scaffold had greater potential for delivery and controlled release of CA and Vc than conventional hydrocolloids, which could provide new insights into the construction of high loading, safe, targeted polyphenol delivery system. [Display omitted] • Easily absorbed Fe2+ acts as a hydrocolloid framework. • Vc prevented CA and Fe2+ oxidation and alleviated CA- Fe2+ antagonism. • Physical cross-linking improved mechanical property of CA-Fe loaded hydrocolloids. • CA-Fe loaded hydrocolloids exhibited promising antioxidant effects. • CA-Fe loaded hydrocolloids displayed satisfactory controlled release. [ABSTRACT FROM AUTHOR]

This study introduces an innovative approach in the field of biomaterials through the development of a multifunctional, printable scaffold designed for the advanced delivery of polyphenols. Addressing challenges of burst-release, poor compounds solubility and bioavailability, we engineered a supramolecular-assembled dual crosslinked hydrogel combining fucoidan (F) and chitosan (CS) encapsulating nanoliposomes. The novel integration of dibenzaldehyde-terminated PEG (DB) within the hydrogel, created a synergistic crosslinking through the formation of the covalent Schiff base bonds and physical interactions which enhanced the hydrogel's overall characteristics. Tailoring F content (DBCS-F), allowed the crosslinking density modulation, yielding a robust gel network structure with enhanced mechanical properties, evidenced by a remarkable compressive stress resistance of 1.73 MPa at 60% strain, coupled with high compressive resilience (79.31% stress recovery after 6 cycles), surpassing single crosslinked hydrogel (DBCS). The rheological analysis further confirmed the hydrogel's improved viscoelasticity, stable network structure, and shear-thinning behavior, affirming its excellent injectability and suitability for 3D printing applications. Most notably, the incorporation of catechin/juglone-loaded nanoliposomes contributed to a pH-responsive sustained release of polyphenols in simulated gastrointestinal conditions. The developed dual crosslinked hydrogel, integrating injectability, self-healing, and pH-responsiveness presents a significant advancement in biomaterials and holds a promising approach for the fabrication of personalized 3D printed scaffolds aimed for sustained and targeted polyphenols release. [Display omitted] • Designed hydrogels with dual crosslinking for tunable structural characteristics. • Obtained nanocomposite hydrogels are injectable, self-healable, and pH-responsive. • Rheological and mechanical properties were enhanced by adjusting fucoidan content. • Nanoliposome inclusion enables effective sustained release of juglone and catechin. • Hydrogel ink displayed excellent extrudability ideal for 3D printing applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • NADES was effective in extracting phenolics from purple araçá byproducts. • Extraction with NADES quantified p-anisic and methoxycinnamic acids. • For the first time, resveratrol was quantified in purple araçá byproducts. • The extract obtained with NADES resulted in a higher anti-diabetic potential. The recovery of bioactive compounds is a promising approach for obtaining rich extracts from fruit by-products. This study investigated the influence of Natural Deep Eutectic Solvents (NADES) and Ultrasound-Assisted Extraction (UAE) on the phenolic content, antioxidant capacity, and in vitro antidiabetic activity of Psidium myrtoides by-product. Among eight NADES evaluated based on choline chloride, NADES ChCl:Gly (1:2) was selected for its efficiency in extracting total phenolic compounds (TPC) with high antioxidant capacity. The optimized conditions were 61 °C, a solid–liquid ratio of 100 mg 5 mL−1, and a 60-minute extraction time. ChCl:Gly exhibited superior TPC recovery (2.6-fold greater effectiveness) compared to the 60 % hydroethanolic solution. Twenty-six phenolic compounds were identified, including significant levels of catechin (336.48 mg g−1) and isoquercetin (26.09 mg g−1). Phenolic acids, such as p -anisic acid (5.47 mg g−1) and methoxyphenylacetic acid (0.23 mg g−1), were identified for the first time in the purple araçá by-product. The ChCl:Gly extract demonstrated the highest bioactivity, showcasing antioxidant and antidiabetic capacities. This study introduces an innovative and sustainable alternative for recovering phenolic compounds from fruit by-products, offering enhanced recovery efficiency and/or selectivity compared to organic solvents. [ABSTRACT FROM AUTHOR]

Bacterial diseases caused by pathogenic bacteria are one of the health problems in recent times. The continuous use of antibiotics and increased hospitalization increased drug resistance. The increased drug resistance has led to the development of novel lead molecules. Hence, alternate medicine or secondary metabolites from plant sources is a possible therapeutic option to treat bacterial infection alone or with existing drugs. The present study aimed to evaluate the antimicrobial property of green tea extract, catechin, benzoyl peroxide and a combination of antibiotics against acne-causing Staphylococcus epidermidis, Staphylococcus aureus, and Propionibacterium acnes isolated from the skin surface of the clinical subjects. The aqueous and solvent extract of green tea showed antibacterial activity against the screened bacteria and it was further improved by combing with existing drugs. The Minimum Inhibitory Concentration (MIC) was performed using the broth dilution method and showed the least MIC value (<2.5 µg/mL). The tea extract exhibited a catechin compound and was determined using High Performance Liquid Chromatography. The mechanism of action of catechin on bacterial pathogens was determined. The catechin treated bacterial cells exhibited morphological changes, structural changes in the cell walls, separation of cells and membrane rupture. The effect of catechin in combination with antibiotics on both Gram-positive and Gram-negative bacteria was antagonistic and synergistic activity. Therefore crude green tea extract and catechin can reduce bacterial infection in acne. [ABSTRACT FROM AUTHOR]

Catechins prevent HFD-induced exacerbation of Salmonella infection. [Display omitted] • Salmonella infection is promoted by HFD in mice. • HFD causes intestinal dysbacteriosis in Salmonella -infected mice. • Catechins exerts protective effects on HFD-fed and Salmonella -infected mice. • C and EGCG modulate the gut microbiota into distinct profiles. Salmonella is one of the most prevalent foodborne pathogens. This study investigated the impact of HFD on Salmonella infection and the preventive effects of tea-derived polyphenols. Results showed that HFD decreased the survival rate of Salmonella -infected mice, while catechin (C) and epigallocatechin gallate (EGCG) supplementation increased survival rates, with EGCG being more effective. HFD promoted pro-inflammatory cytokines and inhibited intestinal epithelial barrier proteins, but catechins, especially EGCG, restored these levels. 16S rDNA sequencing revealed HFD-induced gut microbiota disruptions. Both catechins altered bacterial composition and diversity, with distinct profiles for C and EGCG. The relative abundance of Desulfovibrio and the Eubacterium coprostanoligenes group was modulated by both catechins, and nine bacteria were identified as biomarkers for EGCG treatment. In summary, Salmonella infection is exacerbated by HFD, but catechins, particularly EGCG, offer protective effects, providing valuable insights for controlling pathogenic infections by tea polyphenols or related functional foods. [ABSTRACT FROM AUTHOR]

Theaflavins are beneficial to human health due to various bioactivities. Biosynthesis of theaflavins using polyphenol oxidase (PPO) is advantageous due to cost effectiveness and environmental friendliness. In this review, studies on the mechanism of theaflavins formation, the procedures to screen and prepare PPOs, optimization of reaction systems and immobilization of PPOs were described. The challenges associated with the mass biosynthesis of theaflavins, such as poor enzyme activity, undesirable subproducts and inclusion bodies of recombinant PPOs were presented. Further strategies to solve these challenges and improve theaflavins production, including enzyme engineering, immobilization enzyme technology, water-immiscible solvent-water biphasic systems and recombinant enzyme technology, were proposed. • Enzyme engineering can used to improve the properties of polyphenol oxidase. • Enzyme engineering and immobilized enzyme enhance yield of theaflavins. • Water-immiscible solvent-water biphasic systems can improve theaflavins production. • The subproducts can be reduced by controlling catechin composition and reaction time. • The use of fusion tags and molecular chaperones prevent formation of inclusion body. [ABSTRACT FROM AUTHOR]

Whole grains (WG) are beneficial to health but have reduced sensory quality, partly attributable to inhibition of Maillard reaction products (MRP) by WG phenolics. The study investigated how major flavonoid classes in cereals affect Maillard reaction pathways. Flavonoids were reacted with xylose-lysine aqueous system at 160 °C/12 min. Additionally, breads were made with catechin, and wheat and sorghum bran fortification. Low M w MRP were profiled using UPLC-MS/MS, while melanoidins were characterized using fluorescence spectroscopy and HPSEC-MALS. The flavonoids significantly (p < 0.05) reduced both melanoidin content (by 33–86%) and M w (3.5–15 kDa vs 20 kDa control), leading to lighter bread crust. Flavonoids inhibited MRP via direct condensation with early-stage amines and carbonyls into stable adducts, and reduction of late-stage polymerization reactions, increasing accumulation of cyclic N-containing intermediates. Inhibitory trend was flavones>flavanones>flavanols. C-Ring π-bond dramatically enhance flavonoid MRP inhibition; thus flavone-rich cereal grains are likely to strongly impact MRP-dependent sensory attributes of WG products. • Flavonoids common in grains highly inhibitory or Maillard reaction products (MRP). • Flavonoids reduce melanoidin content and M w , along with bread crust color. • C-Ring π-bond on flavonoids enhanced inhibition of melanoidins and MRP intermediates. • Inhibitory trend flavones>flavanones>flavanols. • Flavonoid profile of ingredients may be used to modulate MRP during food processing. [ABSTRACT FROM AUTHOR]

Tetrastigma hemsleyanum root is a popular functional food in China, and the price varies based on the origin of the product. The link between the origin, metabolic profile, and bioactivity of T. hemsleyanum must be investigated. This study compares the metabolic profiles of 254 samples collected from eight different areas with 49 potential key chemical markers using plant metabolomics. The metabolic pathways of the five critical flavonoid metabolites were annotated and enriched using the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway. Moreover, a random forest model aiding the spectrum-effect relationship analysis was developed for the first time indicating catechin and darendoside B as potential quality markers of antioxidant activity. The findings of this study provide a comprehensive understanding of the chemical composition and bioactive compounds of T. hemsleyanum as well as valuable information on the evaluation of the quality of various samples and products in the market. [Display omitted] • Different areas T. hemsleyanum were effectively distinguished by plant metabolomics. • Significant differential metabolites were mapped to KEGG for metabolic pathways. • Potential biomarkers were screened by random forest assisted spectrum-effect analysis. [ABSTRACT FROM AUTHOR]

The autoxidation of tea catechins by dissolved oxygen proceeds in pH-neutral aqueous solutions, and the major products are oligomers. However, the reaction mechanisms have not been clarified. In this study, the autoxidation of (−)-epigallocatechin-3- O -gallate (1) was examined. The autoxidation with β-cyclodextrin, which includes the A-ring of 1 , significantly suppressed oligomer production and increased the formation of products generated by the oxidative cleavage of the B-ring, indicating the participation of the A-ring in the oligomerization. Further, the autoxidation of 1 in the presence of phloroglucinol, a mimic of the catechin A-ring, yielded products via the nucleophilic addition of phloroglucinol to the B-ring quinone of 1. These results indicated that the oxidative A–B ring couplings accounted for the major oligomerization mechanism. • Autoxidation of epigallocatechin gallate (1) yields oligomers as major products. • The oligomerization was suppressed by presence of β-cyclodextrin. • Autoxidation of 1 with phloroglucinol, a mimic of catechin A-ring, yielded coupling products. • The products were produced by addition of phloroglucinol to B-ring quinone of 1. • The key mechanism of oligomerization is coupling between B-ring quinones and A-rings. [ABSTRACT FROM AUTHOR]

Most teas, including white tea, are produced from tender shoots containing both leaf and stem. However, the effect of the stem on white tea quality remains unclear, especially during withering, an essential process. Therefore, this study investigated the withering-induced changes in the leaves and stems of Camellia sinensis cv. 'Fudingdabai' by multi-group analysis. During withering, the levels of catechin and theobromine (i.e., major flavor-related compounds) decreased slightly, mainly in the leaves. The abundance of some proteinaceous amino acids related to fresh taste increased in stems due to increased protein hydrolysis. In addition, changes in biosynthetic pathways caused a decrease in theanine (a major non-proteinaceous amino acid) and an increase in gamma-aminobutyric acid in stems. Terpenes, mainly in the stems, were partially affected by withering. Phenylacetaldehyde, a major contributor to white tea aroma, increased mainly in the stems. These findings reflect the positive contribution of the stem to white tea quality. • Catechin and theobromine decreased during withering, which mainly occurred in leaf. • Some protein hydrolysis-derived amino acid contents increased in withering stems. • Theanine synthesis decreased and GABA synthesis increased in withering stems. • Stem is vital for bud-leaf type white tea quality, because of its abundant terpenes. • Withering increased the aroma-related phenylacetaldehyde content mainly in the stem. [ABSTRACT FROM AUTHOR]

• EGC, caffeine, catechin, EC, EGCG, and ECG were isolated using HPLC at UPASI 3 and UPASI 17. • Phytochemical levels were relatively higher in UPASI 17 than in UPASI 3. • CHS, F3′5′H, ANS, DFR , and LAR expressions were upregulated in UPASI 17 compared with UPASI 3. • UPASI 17 treated cancer cells elevated the activation of caspase 3 enzyme more effectively than UPASI 3 for apoptosis. Genetically superior tea clones United Planters Association of Southern India (UPASI) 3 and UPASI 17 have been identified as prime candidates for chemo-profiling, assessment of antioxidant activity, and evaluation of anticancer properties against the human adenocarcinoma A549 cancer cell line. High-performance liquid chromatography (HPLC) analysis of UPASI 3 and UPASI 17 revealed the presence of caffeine and five catechins, including epicatechin-3-gallate, catechin, epicatechin, epigallocatechin gallate, and epicatechin gallate, with UPASI 17 exhibiting a higher total catechin content than UPASI 3. Comparative assays of antioxidant capacity and tea quality enzymes, such as total polyphenols, polyphenol oxidase (PPO), superoxide dismutase (SOD), catalase (CAT), phenylalanine ammonia-lyase (PAL), and peroxidase (POD), showed higher levels in UPASI 17 than in UPASI 3. Additionally, transcriptional analysis revealed upregulated expression of key flavonoid biosynthesis genes such as chalcone synthase (CHS), flavonoid 3′,5′-hydroxylase (F3′5′H), anthocyanidin synthase (ANS) dihydroflavonol 4-reductase (DFR) and leucoanthocyanidin 4-reductase (LAR) in UPASI 17 compared with UPASI 3. The anticancer potential of the methanolic extracts of these tea clones against the A549 cancer cell line was evaluated using MTT cytotoxicity assays, along with cell cycle, caspase activation, and mitochondrial membrane potential analyses. Notably, UPASI 17 significantly inhibited cancer cell viability at a concentration of 0.5 µg/ml within 36 h, induced cell cycle arrest in the S phase, and more effectively activated the caspase 3 enzyme to promote apoptosis than UPASI 3. Furthermore, exposure to UPASI 3 and UPASI 17 extracts triggered apoptosis in A549 cells through modulation of the PI3K-Akt-mTOR signalling pathway. The enhanced anticancer activity of UPASI 17 was attributed to its high concentration of phytocompounds and its antioxidant activities. These findings underscore the potential for further molecular-level research and animal studies to develop novel anticancer drugs that target lethal diseases. [Display omitted] [ABSTRACT FROM AUTHOR]

Extraction of green tea catechins and antioxidant activity of tea extracts: [Display omitted] • Extraction of catechins from green tea leaves by microwave-assisted technique. • Effect of solvents, microwave power, and extraction time on the catechins yield. • Quantitative and qualitative analysis of the individual catechins by HPLC. • Antioxidant activity of the various green tea infusions extracted at different conditions. This work aimed to develop a microwave-assisted extraction (MAE) method for green tea to efficiently extract catechins. Green tea was extracted with various solvent types, including water, 50 % ethanol–water, and 50 % acetonitrile–water, with a controlled microwave power of 250–800 W for 2–8 min of irradiation at a fixed temperature of 80 °C. Caffeine from the crude extract was separated by partitioning with chloroform, and catechins were separated using ethyl acetate. The HPLC results demonstrated that maximum yield of catechins (24.7 mg/g for EGC; 8.2 mg/g for C; 14.3 mg/g for EC; 39.6 mg/g for EGCG 14.5 mg/g for GCG and 21.7 mg/g DW tea for ECG) was obtained with a 50 % ethanol–water system at 500 W power within 6 min of treatment. The limits of detection and quantification were in the range of 0.15–0.56 and 0.30–1.23 µg mL−1, respectively. Satisfactory recoveries (0.8–2.7 %) and the intra-day and inter-day precisions (RSD% 1.63–3.84 % and 0.76 %–1.95 %, respectively) were found. The catechin components discovered in green tea included relatively high quantities of epicatechin gallate (ECG), (epigallocatechin gallate (EGCG), and epigallocatechin (EGC). The DPPH assay assessed the antioxidant activity of the various infusions prepared at different parameters. The results demonstrated high antioxidant activity (78.4–94.0 %) for the infusions extracted with the ethanol–water mixture at 500 W microwave power within 6 min of treatment, followed by the acetonitrile–water mixture. The antioxidant potentials of the extracts showed a linear correlation with the catechin contents in the extracts. [ABSTRACT FROM AUTHOR]

At present, consumers increasingly favored the natural food preservatives with fewer side-effects on health. The green tea catechins and black tea theaflavins attracted considerable interest, and their antibacterial effects were extensively reported in the literature. Epicatechin (EC), a green tea catechin without a gallate moiety, showed no bactericidal activity, whereas the theaflavin (TF), also lacking a gallate moiety, exhibited potent bactericidal activity, and the antibacterial effects of green tea catechins and black tea theaflavins were closely correlated with their abilities to disrupt the bacterial cell membrane. In our present study, the mechanisms of membrane interaction modes and behaviors of TF and EC were explored by molecular dynamics simulations. It was demonstrated that TF exhibited markedly stronger affinity for the POPG bilayer compared to EC. Additionally, the hydrophobic interactions of tropolone/catechol rings with the acyl chain part could significantly contribute to the penetration of TF into the POPG bilayer. It was also found that the resorcinol/pyran rings were the key functional groups in TF for forming hydrogen bonds with the POPG bilayer. We believed that the findings from our current study could offer useful insights to better understand the stronger antibacterial effects of TF compared to EC. [Display omitted] • We explored the mechanisms of interactions between TF/EC and bilayers by MD. • Theaflavin showed a markedly stronger affinity for the POPG bilayer compared to EC. • Hydrophobic and h-bond interactions enabled TF's insertion into POPG bilayer. • Resorcinol/pyran rings were key functional groups to form h-bonds with POPG bilayer. [ABSTRACT FROM AUTHOR]

[Display omitted] • Microwave hydrodiffusion and gravity evaluated for pomegranate juice production. • MHG can increase the juice yield up to 55%. • MHG gave a juice rich in catechin and delphinidin-3,5-glucoside. • The lyophilized juices possess anti-glucosidase and anti-glycation activity. Green technologies based on microwaves have been developed by the food industry to produce organoleptically acceptable fruit juices without preliminary processing. Microwave irradiation coupled with hydrodiffusion and gravity (MHG) combines microwave heating with the earth's gravity, allowing the collection of hydrophilic substances released from the irradiated matrix. To the best of our knowledge, MHG extraction has never been experimented to produce pomegranate juice. In this work, we have evaluated it as a potential alternative to the conventional squeezing. A central composite design study (CCD) allowed the selection of the best extractive conditions (irradiation power and extraction time) to obtain a pomegranate juice with higher yield, polyphenol (e.g., catechin and delphinidin-3,5-glucoside) content, and related bioactivities (antioxidant and antidiabetic) than the one obtained by squeezing while maintaining the chemical-physical properties. Thus, this technique appears to be a functional alternative to producing high value pomegranate juice. [ABSTRACT FROM AUTHOR]

The latest insights into the health benefits of various fermented teas, including dark tea, oolong tea, and black tea, underscore the significant role of polyphenols in promoting wellness. The fermentation process in these teas not only enriches their overall polyphenol content but also enhances level of specific polyphenols, improving their health-promoting effects. Dark tea, such as Pu-erh, undergoes microbial fermentation, resulting in unique polyphenol profiles particularly theabrownins that offer potent antioxidant properties. Oolong tea, which is partially oxidized contains catechins and theasinensins, contributing to its potential to enhance weight management and correct metabolic disorders. Black tea, a fully oxidized tea, has a high levels of theaflavins and thearubigins, polyphenols linked to reduced inflammation, decreased incidences of cancer, and enhanced neuroprotection. However, despite these benefits, the emerging understanding of the health risks has associated fermented teas with the presence of potentially harmful compounds formed during fermentation or processing. In dark tea, prolonged microbial fermentation may lead to the production of mycotoxins, such as aflatoxins, which have been linked to carcinogenic effects. Black tea may accumulate heavy metals from soil and processing, posing risks to human health if consumed in excessive amounts. Similarly, oolong tea, while partially fermented, can still contain heavy metals contributing to impaired health. While these risks are generally low and depend on factors such as brewing conditions and consumption frequency, they highlight the importance of conducting future studies to devise preventive measures to mitigate these risks. [ABSTRACT FROM AUTHOR]

This study investigated the food properties, phytochemical profiles, and pharmacological activities of tossa jute sprout, underscoring the exploration of its potential as a functional food. Tossa jute sprout is rich in protein, carbohydrate, fiber, total soluble solids, color content, total energy, vitamins, and minerals, with a lower fat and sugar content. Bioactive compound profiling found that it contains a significant quantity of total phenolics and flavonoids. The HPLC-DAD polyphenol profile detected ten compounds, with 3,4 dihydroxybenzoic acid being the most abundant compound, followed by (−) epicatechin, rosmarinic acid, kaempferol, catechin hydrate, caffeic acid, myricetin, catechol, trans -ferulic acid, and rutin hydrate. It has strong radical scavenging, reducing power, metal chelating power, and total antioxidant power, suggesting this sprout's ability to repair cellular oxidative damage or restore impaired cellular oxidative homeostasis. It also possesses strong α-glucosidase and pancreatic lipase inhibition activities, but mild α-amylase, acetylcholinesterase (AChE), and butyrylcholinesterase (BChE) inhibition activities support the sprout's ability to lower blood sugar, suppress postprandial hyperglycemia, downregulate fat metabolism, and maintain or restore acetylcholine. Overall findings established tossa jute sprout's high potential as a functional food in eliminating malnutrition, maintaining quality health, and eradicating or moderating ailments, including diabetes, obesity, and Alzheimer's. [Display omitted] • Food properties, phytochemicals, and bioactivities of the tossa jute sprout studied. • It is a highly nutrient-rich sprout. • Multifactorial disease-remediation polyphenols are abundant in this sprout. • This sprout has strong antioxidant activities. • It exhibited strong possible antidiabetic, antiobesity, and antiaging properties. [ABSTRACT FROM AUTHOR]

[Display omitted] • Different taste and aroma characteristics were presented in 4 white tea and their processing samples. • The maturity of fresh tea leaves was the primary factor that promoted the formation of milky flavor. • The processing method was the key to inducing milky aroma under mature fresh tea leaves conditions. Targeted metabolomics combined with chemometrics were applied to investigate the flavor profiles of 4 white tea samples, which were produced from different maturity fresh tea leaves with different withering methods. Mature leaves that underwent novel withering process at higher temperature (28-30℃) and humidity (75 ± 3 %) (MN) were characterized by intense milky flavor. The content of free amino acids, catechins, and soluble sugars in MN were significantly lower than that in the other 3 tea samples, resulting in a sweet and mellow taste with low bitterness. Meanwhile, MN possessed the highest intensity of milky aroma, which could be mainly attributed to the existence of dihydro-5-pentyl-2(3H)-furanone and 2-pentyl-furan as the key volatile substances with coconut and creamy fragrance. These findings provide insight into the substance foundations of milky flavor, and identified leaf maturity and processing method as the determining factors of the milk-flavored white tea (MFWT). [ABSTRACT FROM AUTHOR]

In this study, unconventional technologies were used to enhance the phenolic and antioxidant content of zucchini pieces by enriching them with blueberry juice. Our results indicated that ohmic heating (OH) increased the extraction rates of compounds with antioxidant potential in blueberry juice, mainly at 70 °C for 15 min and 7.8 V cm1. Furthermore, OH applied after vacuum impregnation led to higher retention rates of phenolic compounds and antioxidant capacity in zucchini pieces impregnated with blueberry juice, especially at 70 °C for 30 min and 7.8 V cm‐−1. The impregnation process also promoted the darkening of zucchini pieces (due to anthocyanin retention) and increased soluble solids. After drying by hot air and vacuum microwave, the phenolic content, antioxidant capacity, physicochemical and color characteristics of the impregnated and non-impregnated zucchinis were distinctly altered. However, vacuum microwave drying at 120 and 460 W can be suggested as the most suitable conditions for both zucchini products, as it resulted in high concentrations of individual phenolic compounds (e.g. up to 44.25, 8.15, and 2.56 mg 100 g‐−1 dry weight (DW) for catechin, gallic acid, and cyanidin, respectively), as well as total phenolic content of up to 484.37 mg gallic acid equivalent 100 g1 DW, total flavonoid content of up to 197.69 mg catechin equivalent 100 g‐−1 DW, and total monomeric anthocyanins of up to 9.48 mg cyanidin 3-glucosideo equivalent 100 g‐−1 DW. • Vacuum impregnation (VI) with ohmic heating (OH) favor compounds impregnation. • Hot air and vacuum microwave drying (VMD) affect attributes of non- and enriched zucchini. • Cyanidin and epicatechin from blueberry juice were added to the enriched zucchini. • VMD at 120 and 460 W resulted in lower losses of individual phenolic compounds. [ABSTRACT FROM AUTHOR]

Kratom, Mitragyna speciosa , is one of the most popular herbs in the West and Southeast Asia. A number of previous works have focused on bioactive alkaloids in this plant; however, non-alkaloids have never been investigated for their biological activities. Antiviral and virucidal assays of a methanol leaf extract of Kratom, M. speciosa , revealed that a crude extract displayed virucidal activity against the SARS-CoV-2. Activity-guided isolation of a methanol leaf extract of Kratom led to the identification of B-type procyanidin condensed tannins of (−)-epicatechin as virucidal compounds against SARS-CoV-2. The fraction containing condensed tannins exhibited virucidal activity with an EC 50 value of 8.38 μg/mL and a selectivity index (SI) value >23.86. LC-MS/MS analysis and MALDI-TOF MS identified the structure of the virucidal compounds in Kratom as B-type procyanidin condensed tannins, while gel permeation chromatograph (GPC) revealed weight average molecular weight of 238,946 Da for high molecular-weight condensed tannins. In addition to alkaloids, (−)-epicatechin was found as a major component in the leaves of M. speciosa , but it did not have virucidal activity. Macromolecules of (−)-epicatechin, i.e., procyanidin condensed tannins, showed potent virucidal activity against SARS-CoV-2, suggesting that the high molecular weights of these polyphenols are important for virucidal activity. • High amount of (−)-epicatechin was found in leaves of Kratom, Mitragyna speciosa. • Virucidal compounds in Kratom were identified as condensed tannins of (−)-epicatechin. • Procyanidin condensed tannins exhibited virucidal activity against COVID-19 virus with EC 50 value of 8.38 μg/mL. • This work first reports bioactive non-alkaloid compounds in Kratom. [ABSTRACT FROM AUTHOR]

Modifying proteins to enhance their affinity for polyphenols is essential for developing a practical and efficient delivery system that promotes the synergistic effects of bioactive substances. The study investigated the nanoparticle complexation in both pure soy protein isolate (SPI) or SPI modified by ultrasonic combined heat treatment (UHSPI) with varying concentrations of curcumin/catechin (CU/CA) complex, and its effects on the functionality, structure and conformational changes of protein-polyphenol nanocomplexes. Additionally, the intermolecular interaction and co-delivery mechanisms of nanocomplexes were analyzed. Results showed that the physical modification process (28/40 kHz, 90 °C, 15 min) and a rational concentration of CU/CA (0.6 mg/mL) improve the encapsulation efficiency of polyphenols by SPI (up to 77% for curcumin, and 93% for catechin), resulting in a higher DPPH and ABTS scavenging capacity, along with the highest emulsification activity index, as well as enhanced storage stability and thermal stability. The interaction between UHSPI and CU/CA disrupted the protein's secondary structure and exposed more hydrophobic residues to a hydrophilic environment, and exhibited stronger fluorescence quenching. Molecular docking analysis revealed that protein-polyphenol interactions primarily relied on hydrogen bonds and hydrophobic interactions, and 11S subunits exhibited higher affinity with CU/CA. FTIR, fluorescence spectra, and XRD further confirmed the enhanced interaction ability between UHSPI and CU/CA, resulting in the formation of a more stable nanocomplex. Overall, the modified SPI effectively facilitates the co-delivery of an appropriate concentration of curcumin/catechin complex. [Display omitted] • Modified SPI effectively facilitates the co-delivery of curcumin/catechin (CU/CA) complex. • The interaction of UHSPI and CU/CA exhibited stronger fluorescence quenching. • Hydrogen bonds and hydrophobic interactions played major roles in binding process. • Appropriate concentration of CU/CA significantly enhances the stability of the nanocomplexes. [ABSTRACT FROM AUTHOR]

• Physico-chemical characterization of 16 diverse mango genotypes at maturity and deciphering the changes in different phenolic fractions and sugars with different fruit development stage. • LC-MS identified 14 major phenolic fractions in the contrasting mango genotypes. • Gallic acid content was found to increase with the fruit development stage, while catechin content decreased with the fruit development stage. • LC-MS identified glucose, fructose & sucrose as the major fractions. At ripening stage, sucrose was predominant sugar, the other fraction declined. • Results suggest for different indented use based on fruit development stages. Physico-chemical properties of 16 diverse mango genotypes were estimated at ripe stage, besides phenolic and sugar fractions were quantified in eight contrasting genotypes during different fruit developmental stages (egg, mature and ripe). The maximum fruit weight and length (298.33 g, 11.85 cm) were observed in Mallika compared to St. Alexandrina (100.80 g, 7.73 cm). Genotype Langra (861.44 mg/ 100 g) registered the highest total phenolics content, while lowest was in Dashehari (338.73 mg/ 100 g). The genotype Mallika had the maximum total soluble sugars (9.64%), compared to Totapuri (6.43%), which was minimum. Phenolic profiling using LC-MS/MS identified 14 major phenolic fractions, namely, quinic acid, methyl gallate, gallic acid, mangiferin and other minor fractions, of which gallic acid and catechin were further quantified. The gallic acid content was observed to increase from egg stage (0.864 mg/100 g) to ripe stage (3.065 mg/ 100 g). In contrast, catechin content declined from egg stage (0.820 mg/ 100 g) to ripe stage (0.050 mg /100 g). The major sugar fractions identified through LC-MS/MS were glucose, fructose and sucrose, which were found to increase with the advancement in fruit developmental stages, though the sucrose was found highest at ripening. [ABSTRACT FROM AUTHOR]

Due to the relatively low bioavailability of tea phenolics in the small intestine, their reciprocal interaction with gut microbiota in the colon may contribute largely to their beneficial health effects. This implies that tea phenolics may be considered as prebiotics. This review summarizes the current knowledge on the metabolic fates of phenolics from green and black tea, the health benefits of tea phenolics and their microbial metabolites, and the potential underlying mechanisms. Additionally, the prebiotic effects of tea phenolics and conventional oligosaccharide prebiotics are compared. Phenolics from green tea are promptly metabolised into a series of (hydroxylated) phenylcarboxylic acids by gut microbiota, whereas lower degradation rates and metabolite yields are documented for black tea phenolics. Despite these differences, phenolics from green and black tea exhibit comparable gut microbiota modulatory effects. Moreover, intact green and black tea phenolics and their microbial metabolites provide various health benefits upon consumption, most likely due to their anti-oxidation, anti-inflammatory, gut barrier protection, and bile acid metabolism regulatory effects. Overall, the health benefits conferred by tea phenolics via modulation of gut microbiota composition and via formation of health-promoting metabolites is in many ways analogous to the prebiotic action of conventional oligosaccharides prebiotics. Therefore, we conclude that phenolics from green and black tea have the potential to be considered as prebiotics. Gaining better insights in the prebiotic effects of phenolics from green and black tea may pave the way for their high-value application in food and pharmaceutical industries. • Green & black tea phenolics exert health benefits via metabolism in the colon. • Lower metabolic rate and metabolite yields of black tea phenolics. • Similar metabolic fate and gut microbiota modulation by green & black tea phenolics. • Microbial metabolites and gut microbiota modulation beneficial for host's health. • Prebiotic effects of tea phenolics are analogous to conventional prebiotics. [ABSTRACT FROM AUTHOR]

Tea is the most frequently consumed natural beverage across the world produced with the young leaves and shoots of the evergreen perennial plant Camellia sinensis (L.) O. Kuntze. The expanding global appeal of tea is partly attributed to its health-promoting benefits such as anti-inflammation, anti-cancer, anti-allergy, anti-hypertension, anti-obesity, and anti- SARS-CoV-2 activity. The many advantages of healthy tea intake are linked to its bioactive substances such as tea polyphenols, flavonoids (catechins), amino acids (theanine), alkaloids (caffeine), anthocyanins, proanthocyanidins, etc. that are produced through secondary metabolic pathways. Phytohormones regulate secondary metabolite biosynthesis in a variety of plants, including tea. There is a strong hormonal response in the biosynthesis of polyphenols, catechins, theanine and caffeine in tea under control and perturbed environmental conditions. In addition to the impact of preharvest plant hormone manipulation on green tea quality, changes in hormones of postharvest tea also regulate quality-related metabolites in tea. In this review, we discuss the health benefits of major tea constituents and the role of various plant hormones in improving the endogenous levels of these compounds for human health benefits. The fact that the ratio of tea polyphenols to amino acids and the concentrations of tea components are changed by environmental conditions, most notably by climate change-associated variables, the selection and usage of optimal hormone combinations may aid in sustaining tea quality, and thus can be beneficial to both consumers and producers. [Display omitted] • Tea has many health benefits, mostly attributed to tea polyphenols and amino acids. • Phytohormones regulate the biosynthesis of tea catechins, theanine and caffeine. • Usage of optimal hormones can aid in improving tea quality and health benefits. [ABSTRACT FROM AUTHOR]

Bacillus amyloliquefaciens is a promising microbial agent for quality improvement in crops; however, the effects of B. amyloliquefaciens biofertilizers on tea leaf metabolites are relatively unknown. Herein, a combination of metabolome profiling and transcriptome analysis was employed to investigate the effects of foliar spraying with B. amyloliquefaciens biofertilizers on tea leaf quality. The tea polyphenol to amino acid ratio (TP/AA), catechin, and caffeine levels decreased, but theanine level increased in tea leaves after foliar spraying with B. amyloliquefaciens. The differentially accumulated metabolites included flavonoids, phenolic acids, organic acids, amino acids, and carbohydrates. The decrease in catechin was correlated with the catechin/flavonoid biosynthesis pathway. The AMPD gene was highly associated with caffeine content, while the GOGAT gene was associated with theanine accumulation. Foliar spraying with B. amyloliquefaciens biofertilizers may improve summer tea quality. Our findings provide a basis for the application of B. amyloliquefaciens biofertilizers in tea plants and new insights on summer tea leaf resource utilization. • B. amyloliquefaciens reduce catechin accumulation in tea leaves. • B. amyloliquefaciens lower caffeine content by affecting the AMPD gene. • B. amyloliquefaciens raise theanine level by regulating the GOGAT gene. • B. amyloliquefaciens improve summer tea quality. [ABSTRACT FROM AUTHOR]

The Hypericum species (H. perforatum , H. olympicum, and H. orientale) were cultured in hydroponics with excess nickel (Ni, 1 or 100 μM Ni) to compare the metallic and metabolite content. Identical species were collected outdoor to assess the same parameters (including uranium and lanthanides) with total of 53 elements. The results showed that Ni was less accumulated in shoots in hydroponics (translocation factor of 0.01–0.25) and the highest absolute amount was detected in H. olympicum. Essential elements were typically depleted by Ni excess, but Co and Na increased. Soluble phenols, sum of flavonols and catechin rather increased in response to Ni but quercetin glycosides and free amino acids decreased in the shoots of H. olympicum mainly. Comparison of laboratory and outdoor growing plants showed more phenols in outdoor samples but not in H. olympicum and individual metabolites differed too. Plants cultured in hydroponics contained lower amount of non-essential, toxic and rare earth elements (30–100-fold) and shoot bioaccumulation factor in outdoor samples was low for most elements (<0.01) but not for Cd and Pt. Data reveal that H. olympicum is a potent source of phenolic metabolites whereas H. orientale accumulates many elements (38 out of 53 elements). [Display omitted] • Uptake of Ni by 3 Hypericum species in hydroponics and 53 elements were monitored. • The highest Ni amount in H. olympicum depleted quercetin glycosides and amino acids. • Essential elements, but not Co or Na, were typically depleted by Ni excess. • Outdoor plants had more phenols than laboratory ones, but not H. olympicum. • H. orientale control contained the most elements (up to 38) in soil or hydroponics. [ABSTRACT FROM AUTHOR]

• Cyperus rotundus extract supplementation significantly extended the mean lifespan of the Drosophila melanogaster. • Cyperus rotundus extract supplementation significantly increased the antioxidant enzyme activities and increased survival after exposure to hydrogen peroxide and paraquat in D. melanogaster. • Cyperus rotundus extract supplementation improved the resistance to starvation stress, acetic acid-induced stress and decreasing heavy metal-induced toxicity in D. melanogaster. Discovering plant extracts that can help delay the aging process is challenging as the world transitions into an aging society. Cyperus rotundus L. has long been used as a natural medication to cure a variety of disorders in the traditional medical systems of China, India, Africa, Japan, and Arab countries. C. rotundus may be a bioactive substance that can be used to prevent and treat various diseases, as well as prolong life and improve general well-being; however, no data supporting in vivo testing have been reported. This study investigates the effects of C. rotundus extract on the lifespan and stress-induced mortality in Drosophila melanogaster or fruit flies. Different solvent extractions, including ethanol (ECE), 70% ethanol (HECE), methanol (MCE), and water (WCE), of the rhizomes and tubers of C. rotundus were mixed into the diets of flies to determine the lifespan extension property. The most active extract was selected for further testing of resistance to oxidative stress, starvation, acetic acid, and survival from heavy metal-induced toxicity. The phytochemical profiles of the extract were analyzed using LC–MS. The results showed that the mean lifespan-prolonging effects of the extracts in flies were observed in the order of HECE>WEC>MCE>ECE. Supplementation with HECE at 10 mg/mL diet increased the antioxidant enzyme activities and decreased lipid peroxidation compared to the control group. After exposure to hydrogen peroxide and paraquat, Drosophila treated with HECE showed a significant increase in survival. Supplementation with HECE increased resistance to acetic acid and starvation. HECE supplementation also enhanced the survival of fruit flies from iron and aluminum toxicities. LC–MS analysis revealed the major components of epicatechin/catechin, p -coumaric acid, kaempferol, quercetin, and vanillin in HECE. These findings suggest that HECE promotes longevity and increases health by reducing oxidative damage, increasing the adaptive response in stress-induced aging, and decreasing heavy metal-induced toxicity. [ABSTRACT FROM AUTHOR]

Hyaluronic acid (HA)-based antioxidant hydrogels have achieved remarkable results in diabetic wound repair. However, the realization of their glucose-responsive antioxidant functions remains a significant challenge. In this study, we modified hyaluronic acid methacrylate (HAMA) with phenylboronic acid (PBA) and developed a glucose-responsive HA derivative (HAMA-PBA). A glucose-responsive HAMA-PBA/catechin (HMPC) hydrogel platform was then fabricated by forming a borate ester bond between HAMA-PBA and catechin. The results showed that the HMPC hybrid hydrogel not only had a three-dimensional network structure and Young's modulus similar to those of skin tissue, but also possessed biocompatibility. The HMPC hydrogel also showed unique glucose-responsive catechin release behavior and remarkable antioxidant capability, which could effectively eliminate intracellular reactive oxygen species and protect cells from oxidative stress damage (increased superoxide dismutase activity, stabilized reduced glutathione/oxidized glutathione ratio, and reduced malondialdehyde content). Additionally, in vitro and in vivo experimental results showed that the HMPC hydrogel effectively promoted angiogenesis (enhanced VEGF and CD31 expression) and reduced inflammatory responses (decreased IL-6 level and increased IL-10 level), thus rapidly repairing diabetic wounds (within three weeks). This was a significant improvement as compared to that observed for the untreated control group and the HMP hydrogel group. These results indicated the potential for the application of the HMPC hydrogel for treating diabetic wounds. At present, the delayed closure rate of diabetic chronic wounds caused by excessive reactive oxygen species (ROS) remains a worldwide challenge. Hyaluronic acid (HA)-based antioxidant hydrogels have made remarkable achievements in diabetic wound repair; however, the realization of their glucose-responsive antioxidant functions is a tough challenge. In this work, we developed a novel HA-based hydrogel platform with glucose-responsive antioxidant activity for rapid repair of diabetic wounds. In vitro and in vivo experimental results showed that the HMPC hydrogel could effectively promote angiogenesis (enhanced VEGF and CD31 expression) and reduce inflammatory response (decreased IL-6 level and increased IL-10 level), thus rapidly repairing diabetic wounds (within 3 weeks). These results indicated the potential of the HMPC hydrogel for application in diabetic wound treatment. [Display omitted] [ABSTRACT FROM AUTHOR]

This study investigated the influence of the plant part (peel and pulp) on the phenolic compounds, antioxidant activities, and principal component analysis (PCA) of five cactus fruits from the Caatinga, an exclusively Brazilian biome. All species evaluated presented a high total phenolic content (TPC), mainly in their peels. The antioxidant potentials were measured using in vitro assays (2–2-diphenyl-1-picrylhydrazil radical (DPPH·), ferric reducing antioxidant power (FRAP), and β-carotene-linoleic acid assay). The results showed significant differences among the species and among the fruit parts. Pilosocereus gounellei species peel showed the best antioxidant activity both for DPPH and FRAP. However, moderate inhibiting action was found for β-carotene-linoleic acid assay. The species were characterized by the predominance of benzoic acid derivatives bearing a phenol group (salicylic, hydroxybenzoic, and protocatechuic acids), as well as flavonoids (catechin, myricetin and quercetin). Using PCA, it was possible to group the extracts of the cactus peels and pulps to evaluate the relationships between the samples. In most of the cases, the peel represented the main source of phenolic compounds and antioxidant activity. Therefore, the peel of the cacti can be an important by-product for the extraction of antioxidants for industrial purposes. [Display omitted] • Pilosocereus gounellei is an excellent source of natural antioxidants. • The phenolic profile of the fruits of five species of cacti have been described. • The phenol acids and flavonoids are predominant in cacti species. • The peels of cacti species contained highest antioxidant activities. • The phytochemicals of Cactaceae fruit were chemometrically determined. [ABSTRACT FROM AUTHOR]

• Identification of new antivirals and antioxidants in plants is important. • Plants of the genus Spiraea L. have an antiviral and antioxidant potential. • High levels of phenolic compounds were found in Spiraea species. • Antiviral and antioxidant activities of dry Spiraea extracts did not correlate. Plants of the genus Spiraea L. are widespread in Eurasia and North America. They are used in conventional medicine to treat various diseases including colds and such symptoms as a cough, inflammation, and fever. S. hypericifolia L., S. media Schmidt., and S. salicifolia L. are common Spiraea species in nature. The aim of the study was to assess the antiviral and antioxidant potential and to determine the profile and levels of phenolic compounds in dry extracts from the three Spiraea species. Water-ethanol dry extracts were prepared from the aerial parts of the plants. Extracts from the studied Spiraea species had moderate cytotoxicity (CC 50 = 5.6–95.6 μg/mL). Extracts from S. media and S. hypericifolia exerted moderate antiviral activity against influenza A and B viruses (selectivity index of 3 to 21), while the S. salicifolia extract have the highest antiradical activity towards the DPPH (IC 50 38.3 and 35.5 μg/mL). The highest positive correlation with the antiviral activity of the dry extracts was shown by concentrations of flavonoids and glycosides of isorhamnetin in these extracts. The highest positive correlation with the antiradical activity of the dry extracts was manifested by concentrations of catechins and kaempferol glycosides. Thus, dry extracts from the aerial parts of some Spiraea species hold promise for the use and further study as natural inhibitors of influenza A/Puerto Rico/8/34 (H1N1) virus and B/Florida/4/2006 virus replication and as antioxidants. [ABSTRACT FROM AUTHOR]

Cynomorium songaricum is a traditional medicine and also a food material that is eaten raw or processed as tea or beverages. As a featured plant in semi-desert grasslands, C. songaricum is also eaten by the cattle and sheep in the area. This research study fed dairy sheep C. songaricum to determine the flavan-3-ols in sheep milk. Catechin (Cat), epicatechin (Epi), procyanidin A1 (A1), procyanidin A2 (A2), and procyanidin B1 (B1) were detected in sheep milk with the concentration being Epi > A2 > Cat > B1 > A1 at 24 h after the administration of C. songaricum. Neither A1 nor A2 were detected in the methanol extract of C. songaricum. Cysteine degradation of the plant revealed that in addition to Epi, A2 was the extending unit of the polymeric flavan-3-ols in C. songaricum , indicating that A2 is released digestively from the polymers and enters the milk. Procyanidin B-1 was converted to A1 on incubation in raw but not heated milk, indicating that the A1 in milk is the enzymatically transformed product of B1. Accelerated oxidation showed that the flavan-3-ols, B1, Cat, and Epi significantly protects the unsaturated triacyglycerols in the milk from oxidation. The flavan-3-ol could slow down the oxidation of glutathione and the latter may play an important role in preventing the milk triglycerides from oxidation. Flavan-3-ols are polyphenols with many health benefits. The present research revealed the antioxidant activities of flavan-3-ols that could be absorbed to sheep milk, adding new evidences for the values of these flavan-3-ols and for the milk. [Display omitted] [ABSTRACT FROM AUTHOR]

This work characterized bacterial cellulose (BC)/ Uncaria gambir (G) biocomposite film prepared with ultrasonication treatment. Films were prepared from BC powder suspensions in distilled water without and with various loadings (0.05 g, 0.1 g, 0.2 g, 2 g) of G powder then treated using an ultrasonic probe at 1000 W for one hour. The results revealed that the ultrasonication treatment of the suspension greatly increased tensile strength (TS), elongation at break (EB), and toughness (TN) of a BC film by 3097%, 644%, and 32,600%, respectively, compared to non-sonicated BC film. After adding 0.05 g G into the sonicated BC powder suspension, TS, EB, and TN of the biocomposite film were improved to 105.6 MPa, 14.3%, and 8.7 MJ/m3, respectively. The addition of the G increased in antimicrobial activity of the film. This study indicates that biocomposite film is potentially useful for nanopaper production with good antimicrobial and high tensile properties. [ABSTRACT FROM AUTHOR]

The bitter and astringent taste of tea and tea extract is still not favored by many consumers, which limits its applications to bakery foods and functional foods. Many bitter and astringent compounds in tea leaves are susceptible, which transform during tea processing or can be modified by food production technologies. Besides, the accumulations of the major bitter and astringent compounds in fresh tea leaves, such as alkaloids and flavonoids, can be regulated by agronomic practices. Many attempts have been made to reduce the bitter and astringent compounds, in order to improve the sensory quality of tea and tea products. The aim of this review is to describe the characteristics of major bitter and astringent compounds in different types of teas as well as the bitterness and astringency reducing strategies from the aspects of preharvest, processing and post-processing. Alkaloids, catechins, anthocyanins, phenolic acids, flavonol glycosides, and theaflavins importantly contribute to the bitter and astringent taste of tea infusion, the contents of which can be modulated during preharvest, processing, and post-processing. Shade treatment is a conventional agronomic practice to reduce the bitterness and astringency of tea. Processing methods like oxidation, roasting/baking and microbial fermentation effectively reduce the bitter and astringent intensities of teas, but have restricted applications to special types of tea. There is a need of new compounds or strategies to decrease the bitterness and astringency of tea and tea products. Employment of these bitterness and astringency reducing strategies should consider the appearance or application requirements of final products. • Tea taste can be modulated from preharvest, processing, and post-processing. • Shade treatment is an agronomic practice to reduce bitterness and astringency. • PPO-induced enzymatic reaction reduces the bitterness and astringency of tea. • Bitter and astringent flavonoids are susceptible to high temperature. • Microbes transform alkaloids and flavonoids to reduce bitterness and astringency. [ABSTRACT FROM AUTHOR]

This study investigated the effects of sodium pyrophosphate (SPP) and catechin (C) on the in vitro enzymatic digestion of oxidatively damaged myofibrillar protein (MP) gel. The results indicated that SPP increased the β-sheet content and the gastric digestibility of the MP gel, while C hindered the transition from α-helix to β-sheet structure, leading to decreased digestibility. Notably, neither compound significantly affected intestinal digestibility. Furthermore, SPP and C significantly enhanced the antioxidant activity of MP gel digestion products. Notably, their synergistic hydrolysis products, simulating both gastric and gastrointestinal stages, chelated 91.4 % and 89.1 % of Fe2+ and scavenged 59.4 % and 77.6 % of hydroxyl radicals, respectively. Moreover, the final digestion products of the MP gel treated with SPP and C exhibited the highest content of negatively charged amino acids and absolute Zeta potential values. Overall, this study demonstrated that incorporating SPP and C could positively impact the digestion of oxidatively damaged MP gels. [Display omitted] • Myofibrillar protein (MP) is treated with sodium pyrophosphate (SPP) and catechin(C). • SPP significantly enhances the gastric digestibility of the oxidized MP gel. • SPP and C obviously improves the antioxidant activity of MP gel digestion products. • SPP and C collaboration yields the highest levels of negatively charged amino acids. [ABSTRACT FROM AUTHOR]

Tea polyphenols transform under processing methods, but a systematic study on their changes in the same large-leaf tea cultivar is lacking. Here, Camellia sinensis var. assamica cv. Yunkang-10 leaves underwent six processing methods and were assessed using optimized nontargeted (UHPLC-Q-Exactive Orbitrap-MS) and targeted (UHPLC-QqQ-MS) polyphenomics, along with molecular networking analysis. 903 and 52 polyphenolic compounds (catechins, flavones and flavonols, and phenolic acids) were respectively relatively and absolutely quantified for the first time. Dark and black teas, with the lowest polyphenol content, differed from the other four tea types, although variations existed among these four teas. However, some flavonol and flavone aglycones (e.g. kaempferol, apigenin), as well as some phenolic acids (e.g. ellagic acid, gallic acid), exhibited higher levels in dark and black teas. Correlations between polyphenolic composition and electronic sensory characteristics were observed using E-tongue and E-eye. This study enriches understanding of polyphenol profiles in Chinese teas post diverse processing. • Polyphenols underwent first polyphenomics study on the impact of processing. • 903 & 52 polyphenols were quantified by nontargeted/targeted polyphenomics, respectively. • Processing significantly alters polyphenolic compounds in various teas. • Polyphenol profiles of dark and black tea significantly differ from four other types. • Correlations between polyphenol composition & sensory characteristics revealed. [ABSTRACT FROM AUTHOR]

Tea drinking impacts aging and aging-related diseases. However, knowledge of anti-aging molecules other than the major catechins in complex tea extracts remains limited. Here we used Caenorhabditis elegans to analyze the longevity effects of tea extracts and constituents comprehensively. We found that the hot water extract of green tea prolonged lifespan and heathspan. Further, the MeOH fraction prolonged lifespan significantly longer than other fractions. Correlation analysis between mass spectroscopic data and anti-aging activity suggests that ester-type catechins (ETCs) are the major anti-aging components, including 4 common ETCs, 6 phenylpropanoid-substituted ester-type catechins (PSECs), 5 cinnamoylated catechins (CCs), 7 ester-type flavoalkaloids (ETFs), and 4 cinnamoylated flavoalkaloids (CFs). CFs (200 μM) are the strongest anti-aging ETCs (with the longest 73% lifespan extension). Green tea hot water extracts and ETCs improved healthspan by enhancing stress resistance and reducing ROS accumulation. The mechanistic study suggests that they work by multiple pathways. Moreover, ETCs modulated gut microbial homeostasis, increased the content of short-chain fatty acids, and reduced fat content. Altogether, our study provides new evidence for the anti-aging benefits of green tea and insights into a deep understanding of the chemical truth and multi-target mechanism. • Ester-type catechins (ETCs) are the major anti-aging components in green tea. • Cinnamoylated flavoalkaloids extend lifespan >70% in C. elegans. • Lifespan extension is attributed to daf-2 , age-1, daf-16 , sir-2.1 , s kn-1 , aak-2, hsf-1, and eat-2. • ETCs improve intestinal microbes homeostasis and increase content of SCFA. [ABSTRACT FROM AUTHOR]

The high catechin content in summer-to-autumn tea leaves often results in strong, unpleasant tastes, leading to significant resource waste and economic losses due to lignification of unpicked leaves. This study aims to improve the taste quality of summer-to-autumn green teas by combining fine manipulation techniques with hyperspectral observation. Fine manipulation notably enhanced infusion taste quality, particularly in astringency and its aftertaste (aftertasteA). Using Partial Least Squares Discriminant Analysis (PLSDA) on hyperspectral data, 100% prediction accuracy was achieved for dry tea appearance in the near-infrared spectrum. Astringency and aftertasteA correlated with hyperspectral data, allowing precise estimation with over 90% accuracy in both visible and near-infrared spectrums. Epicatechin gallate (ECG) emerged as a key taste compound, enabling non-invasive taste prediction. Practical applications in processing and quality control are demonstrated by the derived equations (Astringency = −0.88 × ECG + 45.401, AftertasteA = −0.353 × ECG + 18.609), highlighting ECG's role in shaping green tea taste profiles. [Display omitted] • Fine-manipulation enhances green tea taste quality from summer-to-autumn leaves. • Near-infrared hyperspectral imaging achieves 100% accuracy in process distinction. • The hyperspectral observation facilitates the estimation of infusion taste. • ECG emerges as a critical compound linking tea appearance to infusion taste. • Astringency = −0.88 × ECG (μg/mL) + 45.401, AftertasteA = −0.353 × ECG (μg/mL) + 18.609. [ABSTRACT FROM AUTHOR]

Kombucha was fermented by the pure cultured tea fungus, and the changes of functional compounds and their transformation were explored. After fermentation, the contents of total polyphenols, total flavonoids, quercetin, kaempferol and catechins respectively enhanced by 77.14%, 69.23%, 89.11%, 70.32% and 45.77% compared with the control, while flavonol glycosides reduced by 38.98%. The bioavailability of polyphenols and flavonoids respectively increased by 29.52% and 740.6%, and DPPH and ABTS respectively increased by 43.81% and 35.08% compared with the control. Correlation analysis showed that microorganisms and the antioxidant activity were highly positive correlation with total polyphenols, total flavonoids, EGC, EC, EGCG, ECG, quercetin and kaempferol, and negative correlation with kaempferol-3-glucoside. The constructed models confirmed that organic acids were more likely to damage the structure of tea leaves, and enzymes (polygalacturonidase and tannase) and solvents (acids, alcohols and esters) had a synergistic effect on the biotransformation of functional compounds. Graphical abstract [Display omitted] • Improving the contents of main functional compounds in kombucha by the tea fungus • Increasing the bioavailability of total polyphenols and total flavonoids in kombucha • Revealing the relationship of the compounds with antioxidant activity and tea fungus • Exploring the biotransformation mechanism of polyphenols and flavonoids [ABSTRACT FROM AUTHOR]

Shaking constitutes a pivotal technique for enhancing black tea quality; nevertheless, its impact on the transformation mechanism of non-volatile metabolites (NVMs) in black tea remains obscure. The present study aimed to investigate the impact of shaking-withering methods (SWM) and traditional-withering methods (TWM) on black tea quality and NVMs conversion. A total of 57 NVMs and 14 objective quantitative indicators were obtained. SWM enhanced sweetness and umami taste, as well as appearance and liquor color brightness of black tea. Eight key differential NVMs were identified by multivariate statistical and dose over threshold value analysis. Metabolic pathway and evolution law analysis revealed that SWM enhanced the oxidation of catechins and flavonol glycosides, promoted the decarboxylation of glutamic acid, then facilitated the formation of theaflavin-3,3′-digallate, finally enhanced the taste and color quality of black tea. This study offers theoretical guidance and technical support for the targeted processing of high-quality black tea. [Display omitted] • Addition of shaking in withering led to sweet taste and bright color in black tea • Eight differential non-volatile metabolites were identified among withering methods • Catechins and flavonoids metabolisms were crucial for tea flavor through shaking • Shaking reduced ester types of catechins and flavonoid glycosides contents • Shaking increased theaflavin-3′-gallate and theaflavin-3,3′-digallate contents [ABSTRACT FROM AUTHOR]

[Display omitted] • Roasting and regions markedly affected Oolong tea taste profile. • 314 non-volatiles related to taste were identified in five varies of Oolong tea. • Roasting processing reflected higher sweet and umami scores. • Catechin, theaflavins, flavonoids and amino acids were key taste compounds. • Catechin was negatively correlated with taste of umami and sweet. The taste profile of oolong tea is intricately shaped by origins and roasting. Herein, a comprehensive approach integrating non-targeted metabolomics, quantitative analysis and sensory evaluations was employed to analyze the taste profile of oolong tea. 25 selected representative oolong teas, including Southern Fujian (MN), Northern Fujian (MB), and Taiwan (TW), were meticulously were classified into SX-RG-DD, GS, and TGY based on the chemical taste phenotypes. A total of 314 non-volatile compounds were identified, among which 87 and 77 compounds, including catechin, theaflavins, flavonoids and amino acids were screened as critical taste metabolites responsible for regions and roasting degree, respectively. The reduction of bitter and astringent, coupled with the enhancement of umami, sweet and sweet aftertaste exhibited a correlation with the decrease in (−)-epigallocatechin (EGC), (−)-epicatechin (EC), (−)-epicatechin gallate (ECG) and (−)-epigallocatechin gallate (EGCG), while the increase in catechin (C). These findings provide insights for further research on optimizing tea quality and refining processing techniques. [ABSTRACT FROM AUTHOR]

• Fertilizer treatments increased total flavonoid and polyphenol contents in tea leaves. • OF and CF + OF treatments increased total amino acids and total catechins content. • CF + OF treatment had the highest tea quality indicated by the lowest CAI and TP/TAA. • Combined fertilizers promoted catechin synthesis by upregulating DFR2, ANS3 , and ANR2. • DFR3, ANS2 , and LAR act as inhibitors for catechin synthesis under combined fertilizers. Fertilizer application plays a crucial role in influencing the metabolites responsible for tea quality control. However, excessive chemical fertilizer application has detrimental effects on tea quality. To explore the influence of chemical and organic fertilizers on tea quality, a pot experiment was conducted with four treatments, including no fertilizer application as control, only chemical fertilizer (CF), only organic fertilizer (OF), and combined chemical fertilizer and organic fertilizers (CF + OF). Total polyphenol (TP), total amino acids (TAA), total flavonoids (TF), catechins and caffeine content, and total phenol-amino ratio (TP/TAA) and catechin astringency index (CAI) were analyzed to evaluate the tea quality, and try to reveal the regulating flavonoids pathway at gene expressional and transcriptomic levels. The results showed that, compared with control, all the fertilizer treatments increased significantly TF (19.70 %, 29.41 % and 64.56 % by CF, OF and CF + OF treatments, respectively) and TP contents (38.90 %, 27.19 % and 16.81 % by CF, OF and CF + OF treatments, respectively). OF and CF + OF treatments increased TAA (by 30.82 % and 38.92 %, respectively), and total catechins content (by 84.25 % and 60.39 %, respectively), while CF treatment decreased total catechins (by 6.83 %). As a result, CF treatment had lower CAI and higher TP/TAA; OF treatment had no effects on CAI and TP/TAA index; while CF + OF treatment had the highest tea quality with the lowest CAI and TP/TAA in the tea leaves. Fertilizers treatments affect flavonoids and catechins contents by regulating the phenylpropanoid and flavonoid biosynthesis pathways involved the modulation of structural genes, such as PAL, 4CL, C4H , and CHS. CF + OF treatment increased expression of genes, particularly DFR2, ANS3 and ANR2 , which promoted the accumulation of (−)-epigallocatechin and (−)-epigallocatechin 3-gallate, ultimately increased total catechin content. This finding provides insight into the mechanisms underlying the effects of CF + OF promotes tea quality, and could provide scientific supports for tea cultivation and management. [ABSTRACT FROM AUTHOR]