Tea: A native source of antimicrobial agents

Changes in amino acids, catechins and alkaloids during the storage of oolong tea and their relationship with antibacterial effect

The storage process has a significant impact on tea quality. Few is known about effect of storage on quality of oolong tea. This study aimed to assess the effect of different storage times on the key chemical components of oolong tea by measuring changes in catechin, free amino acid, and alkaloid content. Variation in the main substances was determined by principal component analysis and heat map analysis. The results revealed notable effects of the storage process on the levels of theanine, epigallocatechin gallate (EGCG), and glutamine. These findings suggest that these compounds could serve as indicators for monitoring changes in oolong tea quality during storage. Additionally, the study observed an increase in the antibacterial ability of tea over time. Correlation analysis indicated that the antibacterial ability against Micrococcus tetragenus and Escherichia coli was influenced by metabolites such as aspartic acid, threonine, serine, gamma-aminobutyric acid, ornithine, alanine, arginine, and EGCG. Overall, this study presents an approach for identifying key metabolites to monitor tea quality effectively with relatively limited data.

Improved antioxidative and antibacterial activity of epigallocatechin gallate derivative complexed by zinc cations and chitosan

Epigallocatechin gallate (EGCG) has attracted increasing attention thanks to its multi-bioactivities, and people are keen on improving the antioxidative and antibacterial performance of EGCG. Based on the favorable biofunctionality of Zn2+ and chitosan (CS), an EGCG derivative with a novel formula, i.e., EGCG-Zn-CS, is presented in this study. The structure of EGCG-Zn-CS was characterized by FT-IR, UV-vis, TGA, XPS, and SEM-EDS. The radical elimination results indicate that 0.1 mg mL-1 of EGCG-Zn-CS demonstrates DPPH radical and hydroxyl radical scavenging activities of 94.8% and 92.3%, while 0.1 mg mL-1 of EGCG exhibits only 78.5% and 75.6%, respectively, which means improved antioxidative activity of EGCG-Zn-CS was obtained. Inhibitory experiments against Staphylococcus aureus and Escherichia coli reveal that the minimal inhibitory concentrations (MICs) of EGCG-Zn-CS were 15.625 μg mL-1 and 187.5 μg mL-1, whereas the minimal bactericide concentrations (MBCs) were 46.875 μg mL-1 and 750 μg mL-1, respectively, which indicate that EGCG-Zn-CS exerts much higher antibacterial activity than EGCG. It can be concluded that the complexing of zinc cations and CS could amazingly improve both the antioxidative and antibacterial activity of EGCG, and it is expected that an exploration of EGCG-Zn-CS may inspire the development of simultaneous effective antioxidant and antibacterial agents.

Impact of internal metal ions in tea polysaccharides on antioxidant potential and suppression of cancer cell growth

Four kinds of tea polysaccharides (MBTPS, MGTPS, ZBTPS, ZGTPS) were extracted from Maofeng black tea, Maofeng green tea,Ziyan black tea and Ziyan green tea, and then four tea polysaccharides (RMBTPS, RMGTPS, RZBTPS, RZGTPS) after metal removal were prepared. The physicochemical properties, antioxidant activity and inhibitory activity on cancer cell proliferation of the above polysaccharides were studied. The composition analysis shows that these tea polysaccharides were glycoproteins complexes, composed of a variety of monosaccharides, and the removal of metal ions did not lead to fundamental changes in the composition of polysaccharides. In vitro activity, after removing metal ions, the ABTS free radicals scavenging ability and reducing power of tea polysaccharides were decreased, and the inhibitory effect on proliferation of H22 cells weakened. There was a great correlation between metal elements Al and Ni and biological activity. The results showed that the metal ions in tea polysaccharides, especially Al and Ni, had positive effects on biological activity.

Comparison of Si-GA-PLS and Si-CARS-PLS build algorithms for quantitation of total polyphenols in black tea using the spectral analytical system

BACKGROUND

The objective of the current study was to compare two machine learning approaches for the quantification of total polyphenols by choosing the optimal spectral intervals utilizing the synergy interval partial least squares (Si-PLS) model. To increase the resilience of built models, the genetic algorithm (GA) and competitive adaptive reweighted sampling (CARS) were applied to a subset of variables.

RESULTS

The collected spectral data were divided into 19 sub-interval selections totaling 246 variables, yielding the lowest root mean square error of cross-validation (RMSECV). The performance of the model was evaluated using the correlation coefficient for calibration (RC ), prediction (RP ), RMSECV, root mean square error of prediction (RMSEP) and residual predictive deviation (RPD) value. The Si-GA-PLS model produced the following results: PCs = 9; RC  = 0.915; RMSECV = 1.39; RP  = 0.8878; RMSEP = 1.62; and RPD = 2.32. The performance of the Si-CARS-PLS model was noted to be best at PCs = 10, while RC  = 0.9723, RMSECV = 0.81, RP  = 0.9114, RMSEP = 1.45 and RPD = 2.59.

CONCLUSION

The build model's prediction ability was amended in the order PLS < Si-PLS < CARS-PLS when full spectroscopic data were used and Si-PLS < Si-GA-PLS < Si-CARS-PLS when interval selection was performed with the Si-PLS model. Finally, the developed method was successfully used to quantify total polyphenols in tea. © 2023 Society of Chemical Industry.

Cytotoxicity, Antimicrobial, Anti-inflammatory and Antioxidant Activity of Camellia Sinensis and Citrus Mediated Copper Oxide Nanoparticle-An In vitro Study

Aim

Several applications of copper oxide nanoparticles (CuONPs) have been documented in various fields, including healthcare, dentistry, medication delivery, tissue and cancer imaging, biolabeling, and biosensing. Therefore, this study aimed to synthesize CuONPs using the plant extracts of Camellia Sinesis (CS) and citrus limon (CL). The nanoparticles were then evaluated for their cytotoxicity, antibacterial, anti-inflammatory, and antioxidant activities.

Materials and Methods

CuONPs were prepared using CS and CL through the green synthesis method. The Zone of Inhibition (ZOI) test was used to assess the antibacterial activity against strains of Staphylococcus aureus, Enterococcus faecalis, Streptococcus mutans, and Candida albicans. The albumin denaturation assay was used to assess the substances' anti-inflammatory activity. The cytotoxicity was determined by conducting the brine shrimp lethality test. Additionally, the antioxidant nature was tested using the 1,1-diphenyl-2-picryl hydrazyl method.

Results

CuONPs mediated by CS and CL were successfully synthesized. The nanoparticles demonstrated significant antimicrobial activity against the bacteria being studied, specifically S. aureus. The cytotoxic effect was observed to be the least when the concentrations were below 20 µL. A potent antioxidant effect, characterized by its maximum absorbance at 517 nm, was observed at a concentration of 50 µL. A significant anti-inflammatory effect was noted for all tested concentrations.

Conclusion

The use of CS- and CL-mediated CuONPs demonstrates a favorable antimicrobial effect with reduced cytotoxicity, as well as improved anti-inflammatory and antioxidant effects at higher concentrations.

Enhancing the antimicrobial activity of silver nanoparticles against ESKAPE bacteria and emerging fungal pathogens by using tea extracts

The sale of antibiotics and antifungals has skyrocketed since 2020. The increasing threat of pathogens like ESKAPE bacteria (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp.), which are effective in evading existing antibiotics, and yeasts like Candida auris or Cryptococcus neoformans is pressing to develop efficient antimicrobial alternatives. Nanoparticles, especially silver nanoparticles (AgNPs), are believed to be promising candidates to supplement or even replace antibiotics in some applications. Here, we propose a way to increase the antimicrobial efficiency of silver nanoparticles by using tea extracts (black, green, or red) for their synthesis. This allows for using lower concentrations of nanoparticles and obtaining the antimicrobial effect in a short time. We found that AgNPs synthesized using green tea extract (G-TeaNPs) are the most effective, causing approximately 80% bacterial cell death in Gram-negative bacteria within only 3 hours at a concentration of 0.1 mg mL-1, which is better than antibiotics. Ampicillin at the same concentration (0.1 mg mL-1) and within the same duration (3 h) causes only up to 40% decrease in the number of S. aureus and E. cloacae cells (non-resistant strains). The tested silver nanoparticles also have antifungal properties and are effective against C. auris and C. neoformans, which are difficult to eradicate using other means. We established that silver nanoparticles synthesized with tea extracts have higher antibacterial properties than silver nanoparticles alone. Such formulations using inexpensive tea extracts and lower concentrations of silver nanoparticles show a promising solution to fight various pathogens.

Recent advances in extending the shelf life of fresh wet noodles: Influencing factors and preservation technologies

Fresh wet noodles (FWNs) are popular among people and have attracted increasing attention because of their characteristics of freshness, chewiness, good taste, and better maintenance of noodle flavor. However, due to the high moisture content and abundance of nutrients in FWN, they are prone to spoilage, which shortens their shelf life and reduces their quality, greatly restricting their large-scale production. Therefore, seeking effective preservation methods to prolong the shelf life is a major breakthrough for the industrialization of FWN. The present review provides a comprehensive overview of the main factors that contribute to the spoilage and degradation of FWN. These factors encompass microorganisms, moisture content, nutritional composition, enzymes, and storage temperature. Moreover, the recent developments in novel shelf-life extension technology applied to FWN, such as chemical preservatives, natural preservatives, physical treatment technologies, and composite preservation technology, are presented and discussed. From the literature reviewed, the application of technologies, such as adding preservatives, modified atmosphere packaging, microwave, cold plasma, ozone, and other technologies, has a certain effect on improving the shelf life of FWN, but the single preservation technology still has some deficiencies. In order to further improve the preservation efficiency, using two or more preservation methods is an important direction for future research on the preservation technology of FWN.

Tea Polyphenols Protects Tracheal Epithelial Tight Junctions in Lung during Actinobacillus pleuropneumoniae Infection via Suppressing TLR-4/MAPK/PKC-MLCK Signaling

Actinobacillus pleuropneumoniae (APP) is the causative pathogen of porcine pleuropneumonia, a highly contagious respiratory disease in the pig industry. The increasingly severe antimicrobial resistance in APP urgently requires novel antibacterial alternatives for the treatment of APP infection. In this study, we investigated the effect of tea polyphenols (TP) against APP. MIC and MBC of TP showed significant inhibitory effects on bacteria growth and caused cellular damage to APP. Furthermore, TP decreased adherent activity of APP to the newborn pig tracheal epithelial cells (NPTr) and the destruction of the tight adherence junction proteins β-catenin and occludin. Moreover, TP improved the survival rate of APP infected mice but also attenuated the release of the inflammation-related cytokines IL-6, IL-8, and TNF-α. TP inhibited activation of the TLR/MAPK/PKC-MLCK signaling for down-regulated TLR-2, TLR4, p-JNK, p-p38, p-PKC-α, and MLCK in cells triggered by APP. Collectively, our data suggest that TP represents a promising therapeutic agent in the treatment of APP infection.

Homo medicus: The transition to meat eating increased pathogen pressure and the use of pharmacological plants in Homo

The human lineage transitioned to a more carnivorous niche 2.6 mya and evolved a large body size and slower life history, which likely increased zoonotic pathogen pressure. Evidence for this increase includes increased zoonotic infections in modern hunter-gatherers and bushmeat hunters, exceptionally low stomach pH compared to other primates, and divergence in immune-related genes. These all point to change, and probably intensification, in the infectious disease environment of Homo compared to earlier hominins and other apes. At the same time, the brain, an organ in which immune responses are constrained, began to triple in size. We propose that the combination of increased zoonotic pathogen pressure and the challenges of defending a large brain and body from pathogens in a long-lived mammal, selected for intensification of the plant-based self-medication strategies already in place in apes and other primates. In support, there is evidence of medicinal plant use by hominins in the middle Paleolithic, and all cultures today have sophisticated, plant-based medical systems, add spices to food, and regularly consume psychoactive plant substances that are harmful to helminths and other pathogens. We propose that the computational challenges of discovering effective plant-based treatments, the consequent ability to consume more energy-rich animal foods, and the reduced reliance on energetically-costly immune responses helped select for increased cognitive abilities and unique exchange relationships in Homo. In the story of human evolution, which has long emphasized hunting skills, medical skills had an equal role to play.

Antibacterial Activity of Epigallocatechin Gallate (EGCG) against Shigella flexneri

Shigella flexneri (S. flexneri), a major intestinal pathogen, is a global public health concern. The biofilms formed by S. flexneri threaten environmental safety, since they could promote the danger of environmental contamination and strengthen the disease-causing properties of bacteria. Epigallocatechin gallate (EGCG) is an important catechin in tea, which has a high antibacterial activity. However, its antibacterial mechanism is still unclear. This research aims to quantify the antibacterial function and investigate the possible mechanism of EGCG inhibition of S. flexneri. The minimum inhibitory concentration (MIC) of EGCG against planktonic S. flexneri in the investigation was measured to be 400 μg/mL. Besides, SDS-PAGE and field emission scanning electron microscopy showed that EGCG interfered with protein synthesis and changed bacteria morphology. Through controlling the expression of the mdoH gene, EGCG was found to be able to prevent an S. flexneri biofilm extracellular polysaccharide from forming, according to experiments utilizing the real-time PCR test. Additional research revealed that EGCG might stimulate the response of S. flexneri to oxidative stress and prevent bacterial growth. These findings suggest that EGCG, a natural compound, may play a substantial role in S. flexneri growth inhibition.

Regulation of fungal community and the quality formation and safety control of Pu-erh tea

Pu-erh tea belongs to dark tea among six major teas in China. As an important kind of post-fermented tea with complex microbial composition, Pu-erh tea is highly praised by many consumers owing to its unique and rich flavor and taste. In recent years, Pu-erh tea has exhibited various physiological activities to prevent and treat metabolic diseases. This review focuses on the fungi in Pu-erh tea and introduces the sources, types, and functions of fungi in Pu-erh tea, as well as the influence on the quality of Pu-erh tea and potential safety risks. During the process of fermentation and aging of Pu-erh tea, fungi contribute to complex chemical changes in bioactive components of tea. Therefore, we examine the important role that fungi play in the quality formation of Pu-erh tea. The associations among the microbial composition, chemicals excreted, and potential food hazards are discussed during the pile-fermentation of Pu-erh tea. The quality of Pu-erh tea has exhibited profound changes during the process of pile-fermentation, including color, aroma, taste, and the bottom of the leaves, which are inseparable from the fungus in the pile-fermentation of Pu-erh tea. Specifically, the application prospects of various detection methods of mycotoxins in assessing the safety of Pu-erh tea are proposed. This review aims to fully understand the importance of fungi in the production of Pu-erh tea and further provides new insights into subtly regulating the piling process to improve the nutritional properties and guarantee the safety of Pu-erh tea.

Effects of Hydrogen Peroxide on In Vitro Cultures of Tea (Camellia sinensis L.) Grown in the Dark and in the Light: Morphology, Content of Malondialdehyde, and Accumulation of Various Polyphenols

Tea plants (Camellia sinensis L.) are phenol-accumulating crops that are widely used for public health. The healing effect of tea leaf products is due to the biosynthesis of such phenolic compounds (PCs) as flavans, which have P-vitamin capillary-strengthening activity. Due to their limited habitat and the value of their specialized metabolites of a phenolic nature, a promising approach is to establish in vitro cultures from them that retain the ability to form PCs, which is characteristic of ex vivo tea plants. The aim of this study was to investigate the effect of exogenic H₂O₂ (0.01 mM; 0.1 mM; 1 mM) on the growth, morphology, degree of stress response, and accumulation of various phenolic compounds in tea plant callus cultures of different ages (24 or 36 days) grown under different cultivation conditions (darkness or light). According to the results obtained, the H₂O₂ effect on tea callus cultures of different ages did not cause changes in their morphophysiological characteristics, both after 2 h of exposure (rapid response of callus culture, RRCC) and after 48 h (delayed response of callus culture, DRCC). The determination of the malondialdehyde (MDA) content, which serves as an indicator of changes in the level of lipid peroxidation (LPO) and the presence of stress responses in plant cells, indicated either its maintenance at the control level, a decrease, or an increase. All these effects depended on the growth conditions of the tea callus cultures (darkness or light), their age, the duration of exposure (rapid or delayed response), and the H₂O₂ concentration. Similar trends were noted for the total content of PCs as well as the amount of flavans, proanthocyanidins (soluble and insoluble forms), and lignin. The plant cell responses reflected changes in its adaptation programs, when specialized metabolites act as a target for the action of H₂O₂, thereby contributing to an increase in their resistance.

A comprehensive review on the prevention and regulation of Alzheimer's disease by tea and its active ingredients

Alzheimer's disease (AD) has brought a heavy burden to society as a representative neurodegenerative disease. The etiology of AD combines multiple factors, concluding family, gender, head trauma, diseases and social psychology. There are multiple hypotheses explaining the pathogenesis of AD such as β-amyloid (Aβ) deposition and tau hyperphosphorylation, which lead to extracellular amyloid plaques and neurofibrillary tangles in neurons. The existing therapeutic drugs have several disadvantages including single target, poor curative effect, and obvious side effects. Tea contains many bioactive components, such as tea polyphenols (TPP), L-theanine (L-TH), tea pigment, tea polysaccharides and caffeine. The epidemiological investigations have shown that drinking tea can reduce the risk of AD. The mechanisms of tea active ingredients in the prevention and regulation of AD includes reducing the generation and aggregation of Aβ; inhibiting tau aggregation and hyperphosphorylation; inhibiting neuronal apoptosis and regulate neurotransmitters; relieving oxidative stress and neuroinflammation as well as the regulation of intestinal flora. This review summarizes the different signaling pathways that tea active ingredients regulate AD. Furthermore, we propose the main limitations of current research and future research directions, hoping to contribute to the development of natural functional foods based on tea active ingredients in the prevention and treatment of AD.

Role of Antimicrobial Drug in the Development of Potential Therapeutics

Population of the world run into several health-related emergencies among mankind and humans as it creates a challenge for the evolution of novel drug discoveries. One such can be the emergence of multidrug-resistant (MDR) strains in both hospital and community settings, which have been due to an inappropriate use and inadequate control of antibiotics that has led to the foremost human health concerns with a high impact on the global economy. So far, there has been application of two strategies for the development of anti-infective agents either by classical antibiotics that have been derived for their synthetic analogs with increased efficacy or screening natural compounds along with the synthetic compound libraries for the antimicrobial activities. However, need for newer treatment options for infectious diseases has led research to develop new generation of antimicrobial activity to further lessen the spread of antibiotic resistance. Currently, the principles aim to find novel mode of actions or products to target the specific sites and virulence factors in pathogens by a series of better understanding of physiology and molecular aspects of the microbial resistance, mechanism of infection process, and gene-pathogenicity relationship. The design various novel strategies tends to provide us a path for the development of various antimicrobial therapies that intends to have a broader and wider antimicrobial spectrum that helps to combat MDR strains worldwide. The development of antimicrobial peptides, metabolites derived from plants, microbes, phage-based antimicrobial agents, use of metal nanoparticles, and role of CRISPR have led to an exceptional strategies in designing and developing the next-generation antimicrobials. These novel strategies might help to combat the seriousness of the infection rates and control the health crisis system.

Tea polyphenols-loaded nanocarriers: preparation technology and biological function

Tea polyphenols (TP) have various biological functions including anti-oxidant, anti-bacterial, anti-apoptotic, anti-inflammatory and bioengineered repair properties. However, TP exhibit poor stability and bioavailability in the gastrointestinal tract. Nanoencapsulation techniques can be used to protect TP and to uphold their original characteristics during processing, storage and digestion, improve their physiochemical properties and enhance their health promoting effects. Nano-embedded TP show higher antioxidant, antibacterial and anticancer properties than TP, allowing TP to play a better role in bioengineering restoration after embedding. In this review, recent advances in nanoencapsulation of TP with biopolymeric nanocarriers (polysaccharides and proteins), lipid-based nanocarriers and innovative developments in preparation strategies were mainly discussed. Additionally, the strengthening biological functions of stability and bioavailability, antioxidant, antibacterial, anticancer activities and bioengineering repair properties activities after the nano-embedding of TP have been considered. Finally, further studies could be conducted for exploring the application of nanoencapsulated systems in food for industrial applications.

Identification of the age of white tea using proton transfer reaction time-of-flight mass spectrometry (PTR-TOF-MS) coupled with multivariate analysis

RATIONALE

In recent years, white tea has become increasingly popular. Some merchants confuse the age of white tea and sell poor-quality products for profit. Therefore, it is necessary to provide technical support for product authentication and valorization in white tea of different marked ages.

METHODS

Volatile organic compounds (VOCs) were detected by proton transfer reaction time-of-flight mass spectrometry (PTR-TOF-MS) and identified as volatile fingerprints. PTR-TOF-MS combined with multivariate analysis was found to identify white tea of four different marked ages (1, 3, 5, and 8 years) for authentication. Principal component analysis (PCA) and orthogonal partial least-squares discriminant analysis (OPLS-DA) were used as classification models to identify key volatile metabolites.

RESULTS

The OPLS-DA model achieved the best results (96.67%, 96.67%, 96.67%, and 96.67% in the training set and 96.00%, 96.00%, 100%, and 100% in the prediction set for 1-year, 3-year, 5-year, and 8-year tea samples, respectively), showing that PTR-TOF-MS with the OPLS-DA model could successfully be used in the identification of white tea with different marked ages. Out of the 60 identified VOCs, 26 volatile materials were closely correlated with tea age and were used as markers to discriminate white tea of different ages.

CONCLUSIONS

PTR-TOF-MS coupled with multivariate analysis could be applied for quality evaluation of tea products of different ages and provided a feasible technical support for product authentication and valorization in white tea of different marked ages.

Elemental Analysis and In Vitro Evaluation of Antibacterial and Antifungal Activities of Usnea barbata (L.) Weber ex F.H. Wigg from Călimani Mountains, Romania

This study aims to complete our research on Usnea barbata (L.) Weber ex F.H. Wigg (U. barbata) from the Călimani Mountains, Romania, with an elemental analysis and to explore its antibacterial and antifungal potential. Thus, we analyzed twenty-three metals (Ca, Fe, Mg, Mn, Zn, Al, Ag, Ba, Co, Cr, Cu, Li, Ni, Tl, V, Mo, Pd, Pt, Sb, As, Pb, Cd, and Hg) in dried U. barbata lichen (dUB) by inductively coupled plasma mass spectrometry (ICP-MS). For the second study, we performed dried lichen extraction with five different solvents (ethyl acetate, acetone, ethanol, methanol, and water), obtaining five U. barbata dry extracts (UBDE). Then, using an adapted disc diffusion method (DDM), we examined their antimicrobial activity against seven bacterial species-four Gram-positive (Staphylococcus aureus, Enterococcus casseliflavus, Streptococcus pyogenes, and Streptococcus pneumoniae) and three Gram-negative (Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa)-and two fungi species (Candida albicans and Candida parapsilosis). Usnic acid (UA) was used as a positive control. The ICP-MS data showed a considerable Ca content (979.766 µg/g), followed by, in decreasing order, Mg, Mn, Al, Fe, and Zn. Other elements had low levels: Ba, Cu, Pb, and Cr (3.782-1.002 µg/g); insignificant amounts (<1 µg/g) of Hg and V were also found in dUB. The trace elements Ag, As, Cd, Co, Li, Tl, Mo, Pd, Pt, and Sb were below detection limits (<0.1 µg/g). The DDM results-expressed as the size (mm) of the inhibition zone diameter (IZs)-proved that the water extract did not have any inhibitory activity on any pathogens (IZs = 0 mm). Gram-positive bacteria displayed the most significant susceptibility to all other UBDE, with Enterococcus casseliflavus showing the highest level (IZs = 20-22 mm). The most susceptible Gram-negative bacterium was Pseudomonas aeruginosa (IZs = 16-20 mm); the others were insensitive to all U. barbata dry extracts (IZs = 0 mm). The inhibitory activity of UBDE and UA on Candida albicans was slightly higher than on Candida parapsilosis.

Antibiofilm Effects of Epigallocatechin Gallate Against Proteus mirabilis Wild-Type and Ampicillin-Induced Strains

Proteus mirabilis is an opportunistic pathogen associated with nosocomial infections and foodborne diseases. The resistance and biofilm formation of P. mirabilis have been a great concern. In this study a multidrug-resistant P. mirabilis strain 012 was exposed to a lethal dose of ampicillin (10 mg/mL, 2.5-fold minimal bactericidal concentration) for 24 h at 37°C. After resuscitation and isolation, five variant isolates were selected and subjected to ampicillin induction by repeatedly streaking on ampicillin-containing plates (10 mg/mL) for at least three times. In biofilm formation assays by using crystal violet staining, we found that the variant strains had enhanced biofilm-forming abilities. (-)-epigallocatechin-3-gallate (EGCG) at a minimum inhibitory concentration (MIC) (256 μg/mL) significantly reduced the biofilm formation of all variant strains and the wild-type strain (p < 0.01). Sub-MIC of EGCG (128 μg/mL) suppressed the biofilms of wild-type and two variants. However, it stimulated the biofilms of the other three variants. The antibiofilm effects of EGCG against the wild-type strain were further confirmed by confocal laser scanning microscopy. Scanning electron microscopy revealed that EGCG induced variants to form more fibrous structures. Our results revealed that a lethal dose of antibiotic exposure increased antibiotic resistance and biofilm formation of P. mirabilis. EGCG may be used as a promising antibiofilm agent to prevent the P. mirabilis biofilm formation in the food industry. However, the sub-MIC of EGCG is not effective and will not be applied.

Beneficial Effects of Green Tea EGCG on Skin Wound Healing: A Comprehensive Review

Epigallocatechin gallate (EGCG) is associated with various health benefits. In this review, we searched current work about the effects of EGCG and its wound dressings on skin for wound healing. Hydrogels, nanoparticles, micro/nanofiber networks and microneedles are the major types of EGCG-containing wound dressings. The beneficial effects of EGCG and its wound dressings at different stages of skin wound healing (hemostasis, inflammation, proliferation and tissue remodeling) were summarized based on the underlying mechanisms of antioxidant, anti-inflammatory, antimicrobial, angiogenesis and antifibrotic properties. This review expatiates on the rationale of using EGCG to promote skin wound healing and prevent scar formation, which provides a future clinical application direction of EGCG.

Antioxidants: Classification, Natural Sources, Activity/Capacity Measurements, and Usefulness for the Synthesis of Nanoparticles

Natural extracts are the source of many antioxidant substances. They have proven useful not only as supplements preventing diseases caused by oxidative stress and food additives preventing oxidation but also as system components for the production of metallic nanoparticles by the so-called green synthesis. This is important given the drastically increased demand for nanomaterials in biomedical fields. The source of ecological technology for producing nanoparticles can be plants or microorganisms (yeast, algae, cyanobacteria, fungi, and bacteria). This review presents recently published research on the green synthesis of nanoparticles. The conditions of biosynthesis and possible mechanisms of nanoparticle formation with the participation of bacteria are presented. The potential of natural extracts for biogenic synthesis depends on the content of reducing substances. The assessment of the antioxidant activity of extracts as multicomponent mixtures is still a challenge for analytical chemistry. There is still no universal test for measuring total antioxidant capacity (TAC). There are many in vitro chemical tests that quantify the antioxidant scavenging activity of free radicals and their ability to chelate metals and that reduce free radical damage. This paper presents the classification of antioxidants and non-enzymatic methods of testing antioxidant capacity in vitro, with particular emphasis on methods based on nanoparticles. Examples of recent studies on the antioxidant activity of natural extracts obtained from different species such as plants, fungi, bacteria, algae, lichens, actinomycetes were collected, giving evaluation methods, reference antioxidants, and details on the preparation of extracts.

Tea polyphenols (TP): a promising natural additive for the manufacture of multifunctional active food packaging films

As a bioactive extract from tea leaves, tea polyphenols (TP) are safe and natural. Its excellent antioxidant and antibacterial properties are increasingly regarded as a good additive for improving degradable food packaging film properties. This article comprehensively reviewed the functional properties of active films containing TP developed recently. The effects of TP addition to enhancing active food packaging films' performance, including thickness, water sensitivity, barrier properties, color, mechanical properties, antioxidant, antibacterial, and intelligent discoloration properties, were discussed. Besides, the practical applications in food preservation of active films containing TP are also discussed. This work concluded that the addition of TP could impart antioxidant and antibacterial properties to active packaging films and act as a crosslinking agent to improve other physical and chemical properties of the film, such as mechanical and barrier properties. However, the effect of TP on specific properties of the active packaging film is complex, and the appropriate TP concentration needs to be selected according to the type of film matrix and the interaction between the components. Notably, the addition of TP improved the efficiency of the active packaging film in food preservation applications, which accelerates the process of replacing the traditional plastic-based food packaging with active packaging film.

Plants and Natural Products with Activity against Various Types of Coronaviruses: A Review with Focus on SARS-CoV-2

COVID-19 is a pandemic disease caused by the SARS-CoV-2 virus, which is potentially fatal for vulnerable individuals. Disease management represents a challenge for many countries, given the shortage of medicines and hospital resources. The objective of this work was to review the medicinal plants, foods and natural products showing scientific evidence for host protection against various types of coronaviruses, with a focus on SARS-CoV-2. Natural products that mitigate the symptoms caused by various coronaviruses are also presented. Particular attention was placed on natural products that stabilize the Renin–Angiotensin–Aldosterone System (RAAS), which has been associated with the entry of the SARS-CoV-2 into human cells.

Preparation and Assessment of Some Characteristics of Nanoparticles Based on Sodium Alginate, Chitosan, and Camellia chrysantha Polyphenols

This paper presents the characteristics, morphology, and properties of alginate/chitosan/polyphenol nanoparticles, in which polyphenols were extracted from Camellia chrysantha leaves collected in Tam Dao district, Vinh Phuc province (Vietnam). The alginate/chitosan/polyphenol nanoparticles were prepared by ionic gelation method at different polyphenol content. The characteristics and morphology of these nanoparticles were investigated using infrared spectroscopy (IR), ultraviolet-visible spectroscopy (UV-Vis), and scanning electron microscopy (SEM). Release kinetic of polyphenols from the alginate/chitosan/polyphenol nanoparticles was conducted in simulated human body fluids. The release kinetics of polyphenols from the above nanoparticles were also evaluated and discussed. The experimental results showed that the release process of polyphenols from the nanoparticles was dependent on three factors: time, pH of solution, and amount of polyphenols.

Tea polyphenols regulate gut microbiota dysbiosis induced by antibiotic in mice

Tea polyphenols (TPs) are now widely used in foods for various biological activities. However, they are rarely used in foods to regulate gut microbiota dysbiosis induced by antibiotics. We assessed the regulation of TPs on gut microbiota with an antibiotic-induced intestinal flora disorder mouse model. The mice were orally administered with cefixime for 8 days, then received TPs for 28 days. We found that the antibiotic had a profound impact on the gut microbiota. Compared with the normal group, significant decreases in the species richness and diversity and the production of short-chain fatty acids (SCFAs) were still observed 28 days after the antibiotic treatment, although there was no significant difference in the colonic mucosa. TPs significantly alleviated the decrease of the richness and diversity of gut microbiota caused by the antibiotic treatment, and significantly increased the relative abundance of beneficial microbes such as Lactobacillus, Akkermansia, Blautia, Roseburia, and Eubacterium. The function prediction showed that TPs significantly decreased the relative abundance of genes related to human diseases, yet significantly increased the relative abundance of genes related to cell growth and death, cell motility, and energy metabolism. These showed that TPs could regulate the gut microbiota dysbiosis induced by antibiotics, thus decreasing the risk of diseases such as obesity, cancer, and diabetes. These suggest that TPs have a great potential to be used as a functional food ingredient to prevent or reduce adverse effects of antibiotics.

Effect-Directed Profiling of Powdered Tea Extracts for Catechins, Theaflavins, Flavonols and Caffeine

The antioxidative activity of Camelia sinensis tea and especially powdered tea extracts on the market, among others used as added value in functional foods, can considerably vary due to not only natural variance, but also adulteration and falsification. Thus, an effect-directed profiling was developed to prove the functional effects or health-promoting claims. It took 3-12 min per sample, depending on the assay incubation time, for 21 separations in parallel. Used as a fast product quality control, it can detect known and unknown bioactive compounds. Twenty tea extracts and a reference mixture of 11-bioactive compounds were investigated in parallel under the same chromatographic conditions by a newly developed reversed phase high-performance thin-layer chromatographic method. In eight planar on-surface assays, effect-directed tea profiles were revealed. Catechins and theaflavins turned out to be not only highly active, but also multi-potent compounds, able to act in a broad range of metabolic pathways. The flavan-3-ols acted as radical scavengers (DPPH^∙ assay), antibacterials against Gram-positive Bacillus subtilis bacteria, and inhibitors of tyrosinase, α-glucosidase, β-glucosidase, and acetylcholinesterase. Further effects against Gram-negative Aliivibrio fischeri bacteria and β-glucuronidase were assigned to other components in the powdered tea extracts. According to their specifications, the activity responses of the powdered tea extracts were higher than in mere leaf extracts of green, white and black tea. The multi-imaging and effect-directed profiling was not only able to identify known functional food ingredients, but also to detect unknown bioactive compounds (including bioactive contaminants, residues or adulterations).

Coronaviruses and Nature's Pharmacy for the Relief of Coronavirus Disease 2019

Current challenges to the treatment of coronavirus disease 2019 should open new prospects in the search for novel drugs from medicinal plants and other natural products. This paper provides details of natural agents that inhibit human coronavirus entry into cells, general replication, and specific chymotrypsin-like protease (3CL^pro)-mediated replication. Medicinal plants, fungi, and marine organisms as remedies for human coronaviruses in China, Lebanon, Malaysia, Singapore, and South Africa are described. Common species include Alnus japonica (Thunb.) Steud., Artemisia annua L., Artemisia apiacea Hance, Astragalus membranaceus (Fisch.) Bunge, Cinnamomum cassia (L.) J.Presl, edible brown algae Ecklonia cava Kjellman, Euphorbia neriifolia L., Glycyrrhiza glabra L., Lonicera japonica Thunb., Pelargonium sidoides DC., Polygonum cuspidatum Siebold & Zucc., Sanguisorba officinalis L., Scutellaria baicalensis Georgi, Toona sinensis (Juss.) M.Roem., and Torreya nucifera (L.) Siebold & Zucc. At least fifty natural compounds, including alkaloids, flavonoids, glycosides, anthraquinones, lignins, and tannins, which inhibit various strains of human coronaviruses, are presented. Given the scarcity of efficacious and safe vaccines or drugs for coronavirus disease 2019, natural products are low-hanging fruits that should be harnessed as the new global frontier against severe acute respiratory syndrome coronavirus 2.

The anti-Zika virus and anti-tumoral activity of the citrus flavanone lipophilic naringenin-based compounds

Flavonoids are natural products widely recognized for their plurality of applications such as antiviral, antiproliferative, antitumor activities and, antioxidant properties. The flavanone naringenin is presented in citrus fruits and has been studied to combat recurrent diseases that still lack effective treatment. Research groups have been investing efforts to the development of new, safe and active candidates to combat these agents or conditions and despite good results recently reported against the Zika virus (ZIKV) and tumor cells, the use of citrus naringenin is limited due to its low bioavailability. Structural exchanges through functionalization, for example, attaching lipophilic groups instead of hydroxyl groups, can further enhance biological properties. Here, the synthesis and characterization of regioselective naringenin mono-7-O-ethers and both mono and di-fatty acid esters, structurally lipophilic ones were demonstrated. Finally, in vitro studies of anti-ZIKV action and antiproliferative activities against melanoma (B16-F10) and breast carcinoma (4T1) cells showed the ether derivatives were actives, with IC₅₀ ranging from 6.76, 18.5 and 22.6 μM to 28.53, 45.1 and 32.3 μM referring to ZIKV, B16-F10 and 4T1 cell lines, respectively. The lipophilic ethers present the ability to inhibit selectively ZIKV-replication in human cells and inhibitions. This class of modifications in flavonoid molecules could be further explore in the future development of specific anti-ZIKV compounds.

Antimicrobial Activity of Extracts of Two Native Fruits of Chile: Arrayan (Luma apiculata) and Peumo (Cryptocarya alba)

Arrayan and peumo fruits are commonly used in the traditional medicine of Chile. In this study, the concentration of the extracts halving the bacterial viability and biofilms formation and disruption of the drug-sensitive and drug-resistant strains of Staphylococcus aureus and Pseudomonas aeruginosa was determined. The chemical composition of extracts was analyzed by high-resolution liquid chromatography coupled with mass spectrometry (U-HPLC/MS). The arrayan extract (Inhibitory concentration IC₅₀ 0.35 ± 0.01 mg/mL) was more effective than peumo extract (IC₅₀ 0.53 ± 0.02 mg/mL) in the inhibition of S. aureus planktonic cells. Similarly, the arrayan extract was more effective in inhibiting the adhesion (S. aureus IC₅₀ 0.23 ± 0.02 mg/mL, P. aeruginosa IC₅₀ 0.29 ± 0.02 mg/mL) than peumo extracts (S. aureus IC₅₀ 0.47 ± 0.03 mg/mL, P. aeruginosa IC₅₀ 0.35 ± 0.01 mg/mL). Both extracts inhibited quorum sensing in a concentration-dependent manner, and the most significant was the autoinducer-2 type communication inhibition by arrayan extract. Both extracts also disrupted preformed biofilm of P. aeruginosa (arrayan IC₅₀ 0.56 ± 0.04 mg/mL, peumo IC₅₀ 0.59 ± 0.04 mg/mL). However, neither arrayan nor peumo extracts disrupted S. aureus mature biofilm. U-HPLC/MS showed that both fruit extracts mainly possessed quercetin compounds; the peumo fruit extract also contained phenolic acids and phenylpropanoids. Our results suggested that both extracts could be used as natural antimicrobials for some skin and nosocomial infections.

Isolation, identification, and biological control in vitro of tail rot pathogen strain from Hippocampus kuda

Tail rot disease is associated with major economic losses in the seahorse aquaculture in China. This study aimed to isolate and identify the pathogen causing tail rot disease in seahorses. Three culturable intestinal bacteria strains were isolated from Hippocampus kuda specimens with tail rot disease. Strain HL11, HL12, and HL13 were identified as Pseudoalteromonas spongiae, Bacillus subtilis and Photobacterium ganghwense based on its morphological characteristics, physiological and biochemical properties, through 16S rRNA and gyrB sequencing, respectively. Challenge experiments using these strains on healthy H. kuda and bacterial re-isolation from challenged diseased seahorses showed that the bacteria strain named HL11 induced identical pathological symptoms, indicating that it is the causative pathogen of the disease. Antibiotic-resistance tests against of 32 antibiotics revealed that HL11 was highly sensitive to 13 kinds, while exhibited intermediate susceptibility to 6, and resistance to 13 kinds. Antibacterial tests of the bioactive agents showed that HL11 was susceptible to five kinds, including tea polyphenols, lactic acid, gallic acid, allicin, and polylysine; however, it was not susceptible to the other 13 kinds of bioactive agents. The results demonstrate the potential of using bioactive agents to replace antibiotics to generate an environmentally friendly mode of culturing seahorses.

Antioxidants of Natural Plant Origins: From Sources to Food Industry Applications

In recent years, great interest has been focused on using natural antioxidants in food products, due to studies indicating possible adverse effects that may be related to the consumption of synthetic antioxidants. A variety of plant materials are known to be natural sources of antioxidants, such as herbs, spices, seeds, fruits and vegetables. The interest in these natural components is not only due to their biological value, but also to their economic impact, as most of them may be extracted from food by-products and under-exploited plant species. This article provides an overview of current knowledge on natural antioxidants: their sources, extraction methods and stabilization processes. In addition, recent studies on their applications in the food industry are also addressed; namely, as preservatives in different food products and in active films for packaging purposes and edible coatings.

Chemical composition, antibacterial activity and related mechanism of valonia and shell from Quercus variabilis Blume (Fagaceae) against Salmonella paratyphi a and Staphylococcus aureus

BACKGROUND

Plant secondary metabolites and phytochemicals that exhibit strong bioactivities have potential to be developed as safe and efficient natural antimicrobials against food contamination and addressing antimicrobial resistance caused by the overuse of chemical synthetic preservative. In this study, the chemical composition, antibacterial activities and related mechanism of the extracts of the valonia and the shell of Quercus variabilis Blume were studied to determine its potential as a safe and efficient natural antimicrobial.

METHODS

The phenolic compositions of valonia and shell extracts were determined by folin-ciocalteau colourimetric method, sodium borohydride/chloranil-based assay and the aluminium chloride method and then further identified by the reverse-phase HPLC analysis. The antibacterial activities of valonia and shell extracts were evaluated by the agar disk diffusion method and agar dilution method. The related antibacterial mechanism was explored successively by the membrane of pathogens effect, phosphorous metabolism, whole-cell proteins and the microbial morphology under scanning electron microscopy.

RESULTS

The n-butanol fraction and water fraction of valonia along with n-butanol fraction of the shell contains enrich phenolics including ellagic acid, theophylline, caffeic acid and tannin acid. The n-butanol fraction and ethanol crude extracts of valonia exhibited strong antibacterial activities against Salmonella paratyphi A (S. paratyphi A) and Staphylococcus aureus (S. aureus) with the DIZ values ranged from 10.89 ± 0.12 to 15.92 ± 0.44, which were greater than that of the Punica granatum (DIZ: 10.22 ± 0.18 and 10.30 ± 0.21). The MIC values of the n-butanol fraction and ethanol crude extracts of valonia against S. paratyphi A and S. aureus were 1.25 mg/ml and 0.625 mg/ml. The related antibacterial mechanism of n-butanol fraction and ethanol crude extracts of valonia may be attributed to their strong impact on membrane permeability and cellular metabolism. Those extracts exhibited strong antibacterial activity according to inhibit the synthesis of bacterial proteins and seriously change morphological structure of bacterial cells.

CONCLUSIONS

The n-butanol fraction and ethanol crude extracts of valonia had reasonably good antibacterial activities against S. paratyphi A and S. aureus. This study suggests possible application of valonia and shell as natural antimicrobials or preservatives for food and medical application.

Inhibition of Virulence-Related Traits in Pseudomonas syringae pv. actinidiae by Gunpowder Green Tea Extracts

Green tea is a widely-consumed healthy drink produced from the leaves of Camellia sinensis. It is renowned for its antioxidant and anticarcinogenic properties, but also displays significant antimicrobial activity against numerous human pathogens. Here we analyzed the antimicrobial activity of Gunpowder green tea against Pseudomonas syringae pv. actinidiae (Psa), the agent that causes kiwifruit bacterial canker. At the phenotypic level, tea extracts strongly inhibited Psa growth and swimming motility, suggesting it could reduce Psa epiphytic survival during plant colonization. The loss of bacterial virulence-related traits following treatment with tea extracts was also investigated by large-scale transcriptome analysis, which confirmed the in vitro phenotypes and revealed the induction of adaptive responses in the treated bacteria allowing them to cope with iron deficiency and oxidative stress. Such molecular changes may account for the ability of Gunpowder green tea to protect kiwifruit against Psa infection.

Polyphenols as natural antioxidants in cosmetics applications

BACKGROUND

Currently, there is a great interest in cosmetics prepared on natural resources bases and this may restrict the use of synthetic substances. Plants play a relevant role as a source of biologically active natural products with cosmetic and dermatological importance. According to this context, polyphenolic extracts are highlighted because they have proven antioxidant, anti-inflammatory, anti-aging, antimicrobial, and supporting activity in solar photoprotection.

AIMS

The purpose this study were reviewed at reporting the antioxidant activity of phenolic compounds, mainly applied to dermatological therapy, and highlighting the action mechanisms and structure-activity relationship.

METHODOLOGY

In September 2017, we performed a literature search in PubMed and Scielo for scientific researches, antioxidant studies, and systemic reviews. The search terms we used were "PHYTOCOSMETICS" AND "ANTIOXIDANT ACTIVITY" OR "PHENOLIC COMPOUNDS" (from 2000). As inclusion criteria were used relevant original articles, scientific research in the area of interest, and crucial reference articles. Exclusion criteria were: duplicate publications, non-relevant articles and not published in English.

RESULTS

The potential cosmetic application of phenolic compounds as natural antioxidants has been attributed to the chemical structure of these compounds, which to interfere in different phases of the oxidation mechanism.

CONCLUSION

The use of phenolic extracts emerges as a viable alternative for cosmetic application, ensuring a commitment to sustainability. However, it is of crucial importance to evaluate the toxicity risks of raw materials and finished products.

Pulsed Electric Field as an Alternative Pre-treatment for Drying to Enhance Polyphenol Extraction from Fresh Tea Leaves

Drying is an essential pre-treatment prior to extraction of tea polyphenols from tea leaves, which is a time and energy-intensive process. In this study, pulsed electric field (PEF) was utilized to replace the conventional thermal dehydration procedure before the phenolic extraction. The influence of different PEF conditions on total polyphenol yield from fresh tea leaves combined with a solid-liquid extraction were compared. PEF treatment at 1.00 kV/cm electric field strength, 100 pulses of 100 μs pulse duration, and 5 s pulse repetition, which delivered 22 kJ/kg and induced 1.5 °C of temperature increase, was used for further study on the extraction kinetics of green tea catechins. The results indicated that compared to oven drying, PEF pre-treatment increased the extraction rate by approximately two times, without significantly altering the phenolic profiles, as revealed by using liquid chromatography combined with mass spectrometry. Scanning electron microscopy imaging revealed that PEF pre-treatment induced the formation of inhomogeneously distributed pores and protuberances on the surface of leaf tissues, which might facilitate the penetration of extraction solvent and the migration of phenolics. This study demonstrates that PEF as a time and energy efficient processing method is a promising alternative for the conventional drying process before further tea polyphenol extraction.

Influences of epigallocatechin gallate and citric acid on Escherichia coli O157:H7 toxin gene expression and virulence-associated stress response

Citric acid and EGCG at their minimum inhibitory concentrations were tested in this study. Logarithmic phase cells of Escherichia coli O157:H7 (ATCC 43895) were exposed to EGCG and citric acid respectively. The results of RT-real time PCR showed that both EGCG and citric acid increased stx2 and oxyR expression and decreased stx1, recA and Q expression. The result of Western blotting for RecA protein further indicated that both EGCG and citric acid decreased RecA production. Both EGCG and citric acid increased the level of intracellular reactive oxygen species and H₂ O₂ production and decreased superoxide dismutase activity. Therefore, EGCG and citric acid might induce stx2 production by increasing oxidative stress response and inhibit stx1 production by suppressing SOS response. In our study, the differential effects of the two antimicrobials were observed. EGCG reduced ompC and rpoS expression. However, citric acid caused an increase in ompC and rpoS expression. Membrane permeability is associated with toxin release. Citric acid increased the outer membrane permeability of E. coli O157:H7. However, the outer membrane of E. coli O157:H7 remained unaffected by EGCG.

SIGNIFICANCE AND IMPACT OF THE STUDY

Shiga toxins are the major virulence factors of Escherichia coli O157:H7. The use of antimicrobials triggering Shiga toxin production is controversial. (-)-epigallocatechin-3-gallate (EGCG) citric acid are often used singly or in combination to prevent micro-organisms in some food products. This study evaluated toxin induction in E. coli O157:H7 in response to EGCG and citric acid and investigated the potential mechanism of action. The findings may contribute to the proper use of EGCG and citric acid as antimicrobials.

Natural antimicrobials for beet leaves preservation: in vitro and in vivo determination of effectiveness

Nisin (Ni), natamycin (Na), green tea extract (GTE) and their combinations were evaluated for controlling beet leaves' native microbiota as well as Listeria innocua and Escherichia coli external contaminations. Antimicrobial effectiveness was evaluated through in vitro and in vivo studies. In the in vitro studies, GTE treatment (0.85%) completely eliminated growth of native microbiota, reduced L. innocua from values of 8.5-3.5 log from 24 h onwards and reduced E. coli below detection limit (DL) after 72 h. Ni (500 IU/mL) was the most effective against L. innocua (7 log CFU/mL reduction) and its combination with GTE presented significant interactions for mesophilic aerobic bacteria (MAB) and L. innocua control. Na (200 ppm) alone or in combination with GTE did not show antimicrobial activity against microorganisms under study. Additionally in vivo evaluation showed that 2.5-5% GTE concentrations are needed to achieve significant inhibitory effects on MAB, L. innocua and E. coli. Furthermore, the best results for MAB and L. innocua control were obtained with the GTE5 + Ni treatment. This study revealed that GTE, either alone or combined with nisin, is a highly promising option with potential for reducing or preventing the growth of pathogenic and spoilage microorganisms present in leafy vegetables, specifically in beet leaves.

Antioxidant and Antimicrobial Activities of (-)-Epigallocatechin-3-gallate (EGCG) and its Potential to Preserve the Quality and Safety of Foods

Quality deterioration of fresh or processed foods is a major challenge for the food industry not only due to economic losses but also due to the risks associated with spoiled foods resulting, for example, from toxic compounds. On the other hand, there are increasing limitations on the application of synthetic preservatives such as antioxidants in foods because of their potential links to human health risks. With the new concept of functional ingredients and the development of the functional foods market, and the desire for a "clean" label, recent research has focused on finding safe additives with multifunctional effects to ensure food safety and quality. (-)-Epigallocatechin-3-gallate (EGCG), a biologically active compound in green tea, has received considerable attention in recent years and is considered a potential alternative to synthetic food additives. EGCG has been shown to prevent the growth of different Gram-positive and Gram-negative bacteria responsible for food spoilage while showing antioxidant activity in food systems. This review focuses on recent findings related to EGCG separation techniques, modification of its structure, mechanisms of antioxidant and antimicrobial activities, and applications in preserving the quality and safety of foods.