Tea Polyphenols Research Articles

Molecular Insights into the Inhibition and Disaggregation Effects of EGCG on Aβ40 and Aβ42 Cofibrillation.

The misfolding and aggregation of amyloid-β (Aβ) peptides play a pivotal role in the pathogenesis of Alzheimer's disease (AD). Aβ40 and Aβ42, the two primary isoforms of Aβ, can not only self-aggregate into homogeneous aggregates but also coaggregate to form mixed fibrils. Epigallocatechin-3-gallate (EGCG), a prominent tea polyphenol, has shown the capability to prevent the self-aggregation of Aβ40 and Aβ42 peptides and disaggregate their homogeneous fibrils. However, its effects on the cofibrillation of Aβ40 and Aβ42 have not yet been explored. Here, we employed molecular dynamic simulations to investigate the effects of EGCG on the coaggregation of Aβ40 and Aβ42, as well as on their mixed fibril. Our findings indicated that EGCG effectively inhibits the codimerization of Aβ40 and Aβ42 primarily by impeding the interchain interaction between the two isoforms. The key binding sites for EGCG on Aβ40 and Aβ42 are the polar residues and aromatic residues, engaging in hydrogen-bond , π-π, and cation-π interactions with EGCG. Additionally, EGCG disaggregates the Aβ40-Aβ42 mixed fibril by reducing its long-range interaction through similar binding sites and interactions as those between EGCG and Aβ40-Aβ42 heterodimers. Our research reveals the comprehensive inhibition and disaggregation effects of EGCG on the cofibrillation of Aβ isoforms, which provides further support for the development of EGCG as an effective antiaggregation agent for AD.

Fabrication of antibacterial poly (L-lactic acid)/tea polyphenol blend films via reactive blending using SG copolymer

Poly (L-lactic acid) (PLLA) composite materials with both excellent antibacterial properties and mechanical properties are highly desirable for both food packaging and biomedical applications. However, a facile method to prepare transparent PLLA composite films with both excellent antibacterial and mechanical properties is still lacking. In this work, blend films based on PLLA, tea polyphenols (TP) and poly (styrene-co-glycidyl methacrylate) (SG) copolymers (PLLA/TP/SG) were prepared by melt blending using twin screw extruder. The blend films showed high transparency with a brownish color originated from tea polyphenols. Both SEM and DSC analyses confirmed that the blends are thermodynamically compatible. GPC and mechanical assessments demonstrated that the PLLA/TP binary blends exhibit reduced molecular weight and compromised mechanical properties, compared to neat PLLA. However, incorporating SG copolymer resulted in increased molecular weight and improved mechanical properties for the PLLA/TP/SG blends. The FT-IR spectra exhibited a shift to lower wavenumber for the absorption peak associated with the benzene ring on TPs after blending with PLLA and SG, indicating the occurrence of transesterification between PLLA and TP. Plate coating studies revealed that the PLLA/TP/SG blends with TP incorporation at 5 wt% exhibited a bacteriostatic rate of 99.99 % against Staphylococcus aureus and Escherichia coli. Overall, our study reveals that the PLLA/TP/SG blend films exhibit excellent antibacterial properties coupled with good mechanical properties, rendering them a promising candidate for antibacterial packaging materials.

Application of Multicolor Fluorescent Carbon Dots Based on Tea Polyphenols in a White Light-Emitting Diode and Room-Temperature Phosphorescence.

Carbon dots (CDs) are new carbon nanomaterials, among which those prepared from biomass are popular due to their excellent optical properties and environmental friendliness. As representative natural phenolic compounds, tea polyphenols are ideal precursors with fluorescent aromatic rings and phenolic hydroxyl structures. Usually, polyphenolic precursors can only be used to produce blue or green fluorescent CDs, and fluorescence in long wavelength domains, such as orange or red, cannot be achieved. Herein, the high reactivity of the phenolic hydroxyl groups in tea polyphenols with o-phthalaldehyde was exploited to modulate the pH during the carbonation process, which led to redshifts of the fluorescence wavelengths. Different pH values during the reaction caused the precursors to take different reaction paths and form fluorescent groups exhibiting different conjugated structures, resulting in carbon dots providing different fluorescent colors. Finally, by utilizing the in situ hydrolysis of ethyl orthosilicate, the tea polyphenol-based carbon dots were embedded into a silica matrix, inducing phosphorescence of the carbon dots. This study provides a new approach for green preparation and application of natural polyphenolic CDs.

Differences and distribution of quality components in Fu brick tea around fungal fermentation

The differences in and distributions of the quality components of Fu brick tea before and after flowering (also called fungal fermentation and known as “Fahua” in China) remain unclear, and the standard of judging quality by the number of golden flowers (GFs; yellow closed capsules of Eurotium cristatum spores) by consumers lacks a scientific foundation. In this study, Fu brick tea (AFT) was obtained from pre-flower raw dark tea (BFT) through the traditional processing of Fu brick tea. The AFT was then hand-selected and divided into pure tea (SFT) and GFs. It was found that the flavonoid, tea polyphenol, free amino acid, aqueous extract, and ester-type catechin content in the AFT were all significantly lower than in the BFT (p < 0.05); the content of 34 types of volatile compound was significantly higher (26 alkanes, 4 alkenes, 2 alcohols, 1 ester, 1 aldehyde) (p < 0.05), and the content of 14 types of volatile compound was significantly lower (6 alkanes, 4 alcohols, 2 esters, 1 ketone, 1 alkene) than in the BFT (p < 0.05). Furthermore, the content of 39 types of nonvolatile substances, including four carboxylic acids, three flavonoids, and D-Arabitol, amino acids and their derivatives, was significantly higher in the AFT (p < 0.05). The content of flavonoids and their derivatives, including 24 types of saturated alkanes and seven types of aldehydes and esters of volatile compounds (3 alkenes, 2 alcohols, 1 ester, and 1 aldehyde) (p < 0.05), was significantly higher in the SFT than in the GFs (p < 0.05). The GFs had significantly higher content of water-soluble leachate, maltose, glycosylated flavonoids, D-salicylose, and amino acids and their derivatives than the SFT (p < 0.05). Widdrol, linalool, N-octanal, and 25 other volatile compounds (9 alkenes, 9alcohols, s aldehydes, 1 ester, 1 alkane, 1 ketone, 1 Naphthalene) were detected only in the GFs.

Development of Assessment Criteria for Managing the Quality of Taishan Black Tea

In order to obtain the quality information of Taishan black tea and provide data support for the establishment of assessment criteria for quality control of Taishan black tea, in this study, 45 samples of Taishan black tea were collected during the summer to investigate their quality characteristics. The results showed that the Taishan black tea typically exhibited a dark-brown, curly appearance and a uniform texture. The tea soup displayed a bright orange-red color. The tea was mainly described as having a fruity aroma, followed by a caramel flavor, sweet aroma, flowery flavor, and clean aroma, with a strong and enduring fragrance. The taste profile was mostly heavy and mellow or heavy and strong, with fewer samples exhibiting slight bitterness and astringency. The tea leaves were characterized by a reddish-auburn color, a soft texture, and an even appearance. The main biochemical components of the Taishan black tea fell within the following ranges: water extracts (38.65–43.35%), free amino acids (1.41–3.45%), tea polyphenols (9.80–15.05%), catechins (6.11–9.03%), and caffeine (1.65–3.05%). The phenolic acid/amino acid ratio was 2.31–6.65%. Catechins and tea polyphenols emerged as critical indicators influencing taste quality, followed by amino acids, water extracts, and caffeine. The aroma analysis identified common compounds, such as 3-methyl-butanal, 2-methyl-butanal, decanal, 2-methyl-propanal, 1-octen-3-ol, and β-ionone, in most samples. These compounds exhibited relatively high contents and high odor activity values, making them the primary contributors to the tea’s aroma. This investigation into the quality of Taishan black tea offers valuable scientific insights, providing a foundation for the standardization of Taishan black tea’s quality.

Bactericidal synergism between engineered endolysin Lysin1902 and tea polyphenols against Escherichia coli O157:H7 in various food products

The endolysin Lysin1902 has bacteriolytic activity but faces challenges in penetrating the bacterial outer membrane (OM). In this study, Lysin1902 was systematically modified to produce the recombinant protein Lysin1902-HP-PC. Although the modification did not affect its inability to cross the bacterial OM, it enhanced its resistance to temperature, pH, and ionic stress. Lysin1902-HP-PC showed a broader antibacterial spectrum compared to Lysin1902. Moreover, when combined with natural tea polyphenols (TP) at 0.3 mg/mL of Lysin1902-HP-PC, the bactericidal concentration of TP was effectively reduced from 1.2 to 0.3 mg/mL while maintaining its antimicrobial effect for over 10 h. A 1:1 ratio combination of Lysin1902-HP-PC and TP at 0.3 mg/mL effectively controlled the bacterial load of Escherichia coli O157:H7 in milk, beef, and lettuce at both 24 and 37 °C. Additionally, this combination treatment efficiently eliminated biofilms on both polystyrene and stainless steel surfaces. The results of our study demonstrated that the combined bactericidal mechanism is initiated by TP-induced damage to the bacterial OM, facilitating the entry of Lysin1902-HP-PC. Subsequently, Lysin1902-HP-PC targeted the bacterial cell wall and destroyed its integrity, thereby disrupting the physiological metabolism of the bacterial cells and causing bacterial cell lysis.

Corn starch/β-Cyclodextrin composite nanoparticles for encapsulation of tea polyphenol and development of oral targeted delivery systems with pH-responsive properties

The development of nano-encapsulated materials with responsive properties for oral targeted delivery systems is innovative and promising. The aim of this study using corn starch (CS) and β-cyclodextrin (β-CD) to prepare composite nanoparticles (CNPs) that can efficiently encapsulate Tea polyphenol (-)-Epigallocatechin gallate (EGCG) with pH-responsive properties for targeted delivery. The results demonstrated that the CNPs prepared with a 1:1 mass ratio of CS and β-CD exhibited excellent stability to pH, ionic concentration, heating and storage conditions, which was mainly driven by hydrogen bonding and hydrophobic interactions. The characterization results showed that tea polyphenol was effectively loaded into the CNPs and the encapsulation and loading rates were 86.96% and 10.87%, respectively. The CNPs encapsulated tea polyphenol exhibited excellent photothermal stability and maintained significant antioxidant activity after 15 days. Additionally, bio-accessibility experiments revealed that the CNPs can resist low pH environments, can be fully released and reach the target site under alkaline conditions, with potential pH-responsive and intestinal-targeted delivery properties. Overall, the CNPs prepared in this study will support to develop pH-responsive characterization of oral targeted delivery systems for the food industry and biomedicine fields.

Multifunctional Dual Network Hydrogel Loaded with Novel Tea Polyphenol Magnesium Nanoparticles Accelerates Wound Repair of MRSA Infected Diabetes

AbstractMethicillin‐resistant Staphylococcus aureus (MRSA) biofilm infection, caused by impaired glucose metabolism in diabetic foot patients, poses a significant obstacle to the healing process and carries a high risk of being life‐threatening. Due to microvascular occlusion and the entrenchment of MRSA biofilms in diabetic foot, controlling and effectively treating MRSA infection remains challenging. Traditional hydrogels suffer from swelling‐related mechanical issues and inadequate drug release control, limiting their applications as biomimetic extracellular matrices for wound healing. Herein, a double‐network hydrogel composed of polyvinyl alcohol, sodium alginate, and gelatin (PSG) loaded with tea polyphenol self‐assembled magnesium nanoparticles (TP‐Mg NPs) with antibacterial and angiogenic properties for treating MRSA‐infected diabetic foot wounds under hyperglycemic conditions is constructed. TP‐Mg@PSG exhibits enhanced mechanical strength and toughness for wound attachment and recovery movement torsion. In the acidic infection microenvironment representative of MRSA‐infected wounds, the TP‐Mg@PSG hydrogel degrades to release TP‐Mg NPs, showing excellent anti‐MRSA biofilm effect and high biocompatibility. Such localized controlled release enhances the inhibition of MRSA infection and reduces the inflammatory response in rats, promoting cell proliferation and rapid wound repair. Therefore, this study presents a multifunctional biomaterial system for managing diabetic foot conditions, highlighting its potential for clinical applications.

Development and Performance Evaluation of Low-Cost Cellophane Paper-Based Biosensors for Polyphenol Detection in Teas: A Cost-Effective Alternative to Teflon® Membranes Biosensors

This study introduces biosensors developed using cellophane paper with immobilized polyphenol oxidase (PPO) from dwarf banana and eggplant peels, integrated with glutaraldehyde and a Clark electrode. These biosensors, optimized for enzyme concentration at 75 units for dwarf banana peel and 100 units for eggplant peel, demonstrated high sensitivity to catechol, paracetamol, pyrogallol, and hydroquinone, similar to traditional Teflon® Clark electrodes. Despite the lower measurement capacity of cellophane membranes (20-30) compared to Teflon's (300-400), the cost-effectiveness and accessibility of cellophane offer a strategic advantage. These biosensors effectively quantified polyphenols in teas, with results closely matching those from the standard Folin-Dennis method and Teflon® electrodes, maintaining a 95% confidence level and an error margin of less than 1%. Hence, the cellophane paper-based biosensors present a cost-effective, efficient alternative for polyphenol detection in teas, promising broader application due to their affordability and performance.

Exploring the Synergistic Effect of Sildenafil and Green Tea Polyphenols on Breast Cancer Stem Cell-like Cells and their Parental Cells: A Potential Novel Therapeutic Approach.

Many cancer studies have intensely focused on the role of diet, among other factors involved in cancer establishment. The positive effect of green tea polyphenols (GTP) on controlling breast cancer cells has been reported in several studies. Cancer stem cell-like cells (CSC-LCs) possessing self-renewal, metastatic, and drug-resistant capacities are considered prominent therapeutic targets. In many tumors, inducible nitric oxide synthase (iNOS) expression levels are high; however, they have a dual effect on breast cancer pathogenesis. This study aimed to investigate the cytotoxicity of the iNOS agonist (Sildenafil) and antagonist (LNAME), both alone and in combination with GTP, on MDA-MB-231, CD44+/CD24- CSC-LCs, and their parental cells (MCF-7). The cell viability assay has been studied using the MTT assay. To analyze drug-drug combinations, CompuSyn and Combenefit software were used. The cytotoxicity mechanism was determined using flow cytometric analysis. L-NAME and GTP showed a synergistic effect on MDA-MB-231 and CSC-LCs. Such an effect was not observed on MCF-7. Sildenafil and GTP, on the other hand, showed synergistic cytotoxicity in all the cells mentioned above. Flow cytometric tests resulted in more than 70% apoptosis in MDA-MB-231 and MCF-7. Also, sub-G1 arrest among MCF-7 cells and a considerable decrease in ROS production by MDA-MB-231 cells following treatment with Sildenafil and GTP were observed. Sildenafil, in combination with flavonoids, may be considered a novel strategy for cancer treatment.

Importance of Thymoquinone, Sulforaphane, Phloretin, and Epigallocatechin and their Health Benefits

Abstract: Natural products have a broad diversity of multidimensional chemical formations, which play an important role, and indicate the crucial nature as a golden source for gaining herbal drug discovery. Thymoquinone performs various functions and impacts anticancer, anti-inflammatory, antioxidant, and anti-diabetic. It shows the significant influence on the treatment of different cancer types, such as bone cancer, bladder cancer, lung cancer, breast cancer, prostate cancer, and colon cancer. Sulforaphane has anticancer and antimicrobial properties and anticarcinogenic constituents. Phloretin is a dihydrochalcone flavonoid that indicates a potent antioxidant activity in peroxynitrite scavenging and restraint of lipid peroxidation. The most important health benefits of phloretin are anti-inflammatory and antioxidant activity and its impacts on cancer cells. Its antioxidant activity occurs through a reducer of lipid peroxidation, the scavenger of ROS, and its anti-inflammatory impacts happen through a declined level of cytokines, adhesion molecules, chemokines, suppression of NF-κβ transcription, and decreased expression of COX- 2 and iNOS. Phloretin impacts cancer cells through cytotoxic and apoptotic activity and activation of immune cells against the tumor. Epigallocatechin-3-gallate is the most abundant tea polyphenol, followed by other polyphenols, namely, catechin, epicatechin, epigallocatechin, and epicatechin-3-gallate. This review manuscript mentions some important medical health advantages and pharmaceutical effects of thymoquinone, sulforaphane, phloretin, and epigallocatechin.

Screening Commercial Tea for Rapid Inactivation of Infectious SARS-CoV-2 in Saliva.

SARS-CoV-2 infects the oral mucosa and is shed in salivary fluids. Traditionally, tea has been used by various cultures to treat respiratory ailments. The objective of this study was to identify commercially available teas that can rapidly inactivate infectious SARS-CoV-2 in saliva. Initially, tea (n = 24) was prepared as 40 mg/mL infusions and incubated with SARS-CoV-2 resuspended in water, for 5 min at 37 °C. Then, five teas that showed >3 log reduction in virus infectivity were further investigated at 40 and 10 mg/mL infusions for 60 and 10 s contact time with SARS-CoV-2 resuspended in saliva. Tea polyphenols were measured using the Folin-Ciocalteu assay. SARS-CoV-2 infectivity was quantified on Vero-E6 cell line using TCID50 assay. At 10 mg/mL infusion, black tea showed the highest reduction (3 log, i.e., 99.9%) of infectious SARS-CoV-2 within 10 s. Green, mint medley, eucalyptus-mint, and raspberry zinger teas showed similar inactivation of SARS-CoV-2 (1.5-2 log, i.e., 96-99% reduction). At 40 mg/mL infusions, all five teas showed >3 log reduction in virus infectivity within 10 s. Tea polyphenol but not pH was significantly correlated to virus reduction. Time-of-addition assay revealed that the five teas displayed preventive effects (0.5-1 log, i.e., 68-90% reduction) against SARS-CoV-2 infection of Vero-E6 cells as well as during post-virus infection (1.2-1.9 log, i.e., 94-98%). However, the highest inhibitory effect was observed when the teas were added at the time of virus infection (2-3 log, i.e., 99-99.9%). Our results provide insights into a rapid at-home intervention (tea drinking or gargling) to reduce infectious SARS-CoV-2 load in the oral cavity which might also mitigate infection of the oral mucosa.

Epigenetics in obesity: Mechanisms and advances in therapies based on natural products.

Obesity is a major risk factor for morbidity and mortality because it has a close relationship to metabolic illnesses, such as diabetes, cardiovascular diseases, and some types of cancer. With no drugs available, the mainstay of obesity management remains lifestyle changes with exercise and dietary modifications. In light of the tremendous disease burden and unmet therapeutics, fresh perspectives on pathophysiology and drug discovery are needed. The development of epigenetics provides a compelling justification for how environmental, lifestyle, and other risk factors contribute to the pathogenesis of obesity. Furthermore, epigenetic dysregulations can be restored, and it has been reported that certain natural products obtained from plants, such as tea polyphenols, ellagic acid, urolithins, curcumin, genistein, isothiocyanates, and citrus isoflavonoids, were shown to inhibit weight gain. These substances have great antioxidant potential and are of great interest because they can also modify epigenetic mechanisms. Therefore, understanding epigenetic modifications to target the primary cause of obesity and the epigenetic mechanisms of anti-obesity effects with certain phytochemicals can prove rational strategies to prevent the disease and develop novel therapeutic interventions. Thus, the current review aimed to summarize the epigenetic mechanisms and advances in therapies for obesity based on natural products to provide evidence for the development of several potential anti-obesity drug targets.

A REVIEW OF KOMBUCHA ANTIOXIDANT EFFECTS ON ATHEROSCLEROSIS IN PRECLINICAL STUDIES

Background Atherosclerosis is the leading cause of death among cardiovascular diseases in Indonesia, in which death is possible if uncontrolled. The prevalence of the disease may be prevented by consuming foods or drinks containing high levels of antioxidant such as kombucha. Exploration of kombucha properties as an antioxidant that will improve atherosclerosis could be obtained from preclinical studies. Objective To discuss the antioxidant effect of kombucha on atherosclerosis in preclinical studies. Method This study is a narrative review with literatures from 2013 to 2022. Result Kombucha is an antioxidant-rich beverage made from enzymes generated by the SCOBY bacteria, which are fermented in sweet tea for 7-14 days to achieve optimal quantities of polyphenols. In addition to the antioxidants in the blood, the effect will lower the levels of LDL, VLDL, triglycerides, and total cholesterol in the blood. Moreover, it can increase HDL in blood and inhibit lesion forming in the aorta. Conclusion Polyphenol in kombucha tea has an antiatherogenic effect that may prevent atherosclerosis in preclinical studies. Keywords: antioxidant, atherosclerosis, kombucha, polyphenol

Effect of polyphenols on the rheology, microstructure and in vitro digestion of pea protein gels at various pH

Polyphenols exist widely in plants and interact with plant proteins distinctly depending on the environmental pH. This could potentially affect the gelling property of plant proteins and their digestion. In the present study, pea protein suspensions containing 0 %, 0.5 % and 1 % green tea polyphenols (GTP) were heated to form gels at pH5, pH7, and pH8.5. A strain amplitude sweep showed that the storage modulus (G’) and critical strain of pea protein gels decreased with increased GTP concentration at all examined pH. Gelation dynamic showed gelling of pea protein-GTP was delayed at pH7 and pH8.5 compared to the control. Differential scanning calorimetry showed that pea proteins became less heat resistant in the presence of GTP at pH5 and pH7, but not at pH8.5. Ultra-small and small-angle X-ray scattering showed that the radius of gyration of small- and medium-sized aggregates in pea protein gels was increased ∼10–16 % and 22–30 % at pH7 and pH8.5, respectively when 1 % GTP was present. Under such pH conditions, the proportion of structure with a radius of ∼10–200 nm was increased in pea protein-GTP gels based on the volume size distribution. In vitro digestion found the soluble protein content of digesta of pea protein-GTP gels had a 5–8.5 % decrement with the presence of larger peptides when compared to pea protein gels.

Targeting ERS-mitophagy in hippocampal neurons to explore the improvement of memory by tea polyphenols in aged type 2 diabetic rats

Increasing evidence demonstrated that mitophagy and endoplasmic reticulum stress (ERS) was closely associated with memory decline in elderly type 2 diabetes mellitus (T2DM). Tea polyphenols (TP), an excellent natural antioxidant, has been reported to have neuroprotective properties in aging and diabetes, but the underlying mechanisms are still not fully understood. This study targets ERS-mitophagy in hippocampal neurons to investigate the improvement effect of memory in aged T2DM rats by TP. Rats were randomly divided into the control group, the aged group, the aged T2DM model group, the TP 75, 150, 300 mg/kg groups. TP 300 mg/kg ameliorated mitophagy by decreasing the levels of p-mTOR (S2448), P62 and HSP60 and increasing the levels of PINK1 and Parkin, the ratio of LC3Ⅱ/LC3Ⅰ, co-localization of LC3 and HSP60 and the number of autophagosomes and autolysosomes. TP 300 mg/kg attenuated ERS by downregulating the levels of p-PERK, p-eIF2α, ATF4, GRP78 and restoring the ER structure. To further verify epigallocatechin gallate (EGCG), which is the main active component of TP, enhanced mitophagy by inhibiting ERS, PC12 cells were pretreated with ERS activator tunicamycin (TM) or ERS inhibitor 4-phenylbutyric acid (4-PBA). The results showed that the improvement of mitophagy by EGCG was inhibited by TM and promoted by 4-PBA. Collectively, ERS-mitophagy in hippocampal neurons plays a key role in the improvement of memory by TP in aged T2DM rats. This study will provide a new perspective and strategy for the prevention of memory decline in elderly with T2DM.

Effects of Different Expansion Temperatures on the Non-Volatile Qualities of Tea Stems

Tea stems are a type of tea by-product, and a considerable amount of them is discarded during picking, with their value often being overlooked. To enhance the utilization of tea stems, we investigated the effects of different expansion temperatures on the non-volatile compounds of tea stems. The results showed that the contents of EC, EGC, EGCG, tea polyphenols, and amino acids all decreased with the expansion temperature, while the contents of GA and C increased. The best effect was observed at 220 °C for 20 s. Additionally, as the temperature increased, the umami and aftertaste of astringency values of tea stems decreased, and the value of bitterness increased. Meanwhile, the value of sweetness decreased first and then increased. EGC was identified as the key differential compound of tea stems at different temperatures. In this investigation, determining the optimum expansion temperature was deemed advantageous for enhancing the flavor quality of tea stems, consequently elevating the utilization efficacy of tea stems and tea by-products.

Antimicrobial and antioxidant activity of encapsulated tea polyphenols in chitosan/alginate-coated zein nanoparticles: a possible supplement against fish pathogens in aquaculture.

Regulation of antibiotic use in aquaculture calls for the emergence of more sustainable alternative treatments. Tea polyphenols (GTE), particularly epigallocatechin gallate (EGCG), have various biological activities. However, tea polyphenols are susceptible to degradation. In this work, EGCG and GTE were encapsulated in zein nanoparticles (ZNP) stabilized with alginate (ALG) and chitosan (CS) to reduce the degradation effect. ALG-coated ZNP and ALG/CS-coated ZNP encapsulating EGCG or GTE were obtained with a hydrodynamic size of less than 300 nm, an absolute ζ-potential value >30 mV, and an encapsulation efficiency greater than 75%. The antioxidant capacity of the encapsulated substances, although lower than that of the free ones, maintained high levels. On the other hand, the evaluation of antimicrobial activity showed greater efficiency in terms of growth inhibition for ALG/CS-ZNP formulations, with average overall values of around 60%, reaching an inhibition of more than 90% for Photobacterium damselae. These results support encapsulation as a good strategy for tea polyphenols, as it allows maintaining significant levels of antioxidant activity and increasing the potential for antimicrobial activity, in addition to increasing protection against sources of degradation.

Effects of Complex Antioxidants Added to Chicken Diet on Growth Performance, Serum Biochemical Indices, Meat Quality, and Antioxidant Capacity

This study aimed to evaluate the effects of diets supplemented with various levels of complex antioxidants (CA) containing tertiary butylhydroquinone (TBHQ) and tea polyphenols (TP) on growth performance, meat quality of breast and leg muscles, serum biochemistry, and antioxidant capacity of serum, liver, breast meat, jejunum, and ileum in broilers. A total of 600 one-day-old Arbor Acres male broilers with similar body weights were randomly divided into three groups (10 replicates/group, 20 broilers/replicate). Birds in the three experimental groups were fed a basal diet with CA at 0, 300, and 500 mg/kg. The results showed that supplementing with 300 mg/kg CA significantly increased (p &lt; 0.05) 42 d BW and 22–42 d ADG, and markedly decreased (p &lt; 0.05) 22–42 d F: G ratio in comparison to the control group. Birds fed a diet with 300 mg/kg CA had a higher (p &lt; 0.05) pH of chicken meat at 24 h and 48 h post mortem and lower (p &lt; 0.05) yellowness values (b*) of chicken meat at 45 min and 24 h post mortem, along with a lower (p &lt; 0.05) cooking loss. Supplementing with 300 mg/kg CA significantly increased (p &lt; 0.05) serum and liver T-SOD activity, serum T-AOC level, as well as jejunual GST activity, and significantly decreased (p &lt; 0.05) liver MDA content when compared with the control group. These results indicate that diet supplementation with 300 mg/kg CA containing TBHQ and TP could improve growth performance and meat quality by increasing the antioxidant capacity of broilers.

A sensor array based on a nanozyme with polyphenol oxidase activity for the identification of tea polyphenols and Chinese green tea

Green tea is popular among consumers because of its high nutritional value and unique flavor. There is often a strong correlation among the type of tea, its quality level and the price. Therefore, the rapid identification of tea types and the judgment of tea quality grades are particularly important. In this work, a novel sensor array based on nanozyme with polyphenol oxidase (PPO) activity is proposed for the identification of tea polyphenols (TPs) and Chinese green tea. The absorption spectra changes of the nanozyme and its substrate in the presence of different TPs were first investigated. The feature spectra were scientifically selected using genetic algorithm (GA), and then a sensor array with 15 sensing units (5 wavelengths × 3 time) was constructed. Combined with the support vector machine (SVM) discriminative model, the discriminative rate of this sensor array was 100% for different concentrations of typical TPs in Chinese green tea with a detection limit of 5 μM. In addition, the identification of different concentrations of the same tea polyphenols and mixed tea polyphenols have also been achieved. Based on the above study, we further developed a facile and efficient new method for the category differentiation and adulteration identification of green tea, and the accuracy of this array was 96.88% and 100% for eight types of green teas and different adulteration ratios of Biluochun, respectively. This work has significance for the rapid discrimination of green tea brands and adulteration.