Comparative assessment of total polyphenols, antioxidant and antimicrobial activity of different tea varieties of Bangladesh

Metabolomics-based analysis of the effects of differences in soluble sugars on the sweetness quality of six major tea types in China

Soluble sugars are indeed key factors in the formation of tea sweetness quality. However, the specific impact they exert on tea sweetness has not been clearly elucidated. Consequently, in this study, one bud and two leaves of the same tea variety were utilized to produce six types of tea for sensory evaluation, electronic tongue analysis, and targeted sugar metabolomics analysis, aiming to systematically assess the influence of soluble sugars on the sweetness contribution in different teas. The results obtained from sensory evaluation and the electronic tongue indicate that the sweetness order of various teas is green tea (GT) > yellow tea (YT) > dark tea (DT) > oolong tea (OT) > black tea (BT) > white tea (WT). Through metabolomics, 26 crucial differential metabolites were identified, among which sucrose, inositol, D-fructose, glucose, and D-arabinitol constitute the main sugar components that distinguish the sweetness characteristics of the six types of tea. This study offers a comprehensive and detailed overview of the effects of commonly employed processing methods on the sweetness quality of tea as well as its metabolic properties. It thereby lays a solid theoretical foundation for optimizing processing techniques to enhance the sweetness quality of tea and to better serve tea production practices.

Carotenoids in Paprika Fruits and Ajvar: Chemical Characterization and Biological Activity

In this study, carotenoids from four different paprika genotypes were analyzed at various maturation stages, as well as in Ajvar, a traditional Balkan product made from fully matured roasted paprika fruits. For this purpose, the HPTLC analytical method was used, and five dominant carotenoids were analyzed: β-carotene, lutein, zeaxanthin, capsanthin, and β-cryptoxanthin. Additionally, total carotenoids were analyzed spectrophotometrically, antioxidant capacity was determined, and their bioavailability was assayed using in vitro digestion. Finally, Raman spectroscopy, a non-destructive analytical method, was used to estimate the total carotenoid content. The results showed that the amount of all investigated carotenoids is the highest in the final maturity stage (0.38 g/100 g DM to 1.55 g/100 g DM). On the other hand, the lowest concentration of all investigated carotenoids was detected at the first stage of maturation, ranging from 0.01 g/100 g DM to 0.25 g/100 g DM. However, the analysis of carotenoid content in Ajvar showed a tendency for a decrease in concentration compared to their quantity in fresh fruits, although this was also dependent on the genotype (1.9-66.98% according to HPTLC results and 16.14-82.36% according to spectrophotometry). Antioxidant tests indicated an increase in antioxidant capacity with the ripening of paprika fruits, confirming the role of carotenoids as compounds capable of neutralizing harmful oxygen species (DPPH ranged from 0.21 to 1.50 µmol/g TEAC, CUPRAC ranged from 0.185 to 0.297 mg AsA/g DM, FRP ranged from 9.33 to 25.66 mg AsA/g DM). Quantification of total carotenoids by Raman spectroscopy showed that results were highly correlated with those obtained by HPTLC and the spectrophotometric method, highlighting the potential of Raman spectroscopy for carotenoid quantification. Based on the obtained results, it can be concluded that the traditional product Ajvar represents an important source of carotenoids, which are preserved after heat treatment with high biological activity relative to the final ripening stage of the paprika. Furthermore, the bioavailability of carotenoids from Ajvar is significantly higher compared to the results from fresh paprika analysis.

Influence of varied processing methods on the antioxidant capacity, antibacterial activity, and bioavailability of Iranian black, oolong, and green leafy teas

In this study, the impact of various tea preparation techniques on the content of bioactive compounds, antioxidant capacity, antibacterial properties, and polyphenol bioavailability in green, black, and oolong tea infusions was examined. The findings demonstrated that the fermentation process significantly influences the levels of bioactive compounds, with green tea infusions exhibiting the highest, and black tea the lowest, content of phenolic compounds. A positive correlation was observed between the content of the phenolic compound and both antioxidant and antibacterial activities. Additionally, the microwave brewing method was identified as the most effective preparation technique for maximizing the bioactive compound content and bioavailability. The inclusion of skim milk powder was found to further enhance the bioavailability of phenolic compounds during digestive process. The research suggests that green tea infusions prepared using the microwave brewing method and supplemented with the skim milk powder, could serve as a functional beverage offering enhanced health benefits.

From Spent Black and Green Tea to Potential Health Boosters: Optimization of Polyphenol Extraction and Assessment of Their Antioxidant and Antibacterial Activities

Tea, one of the most popular beverages worldwide, generates a substantial amount of spent leaves, often directly discarded although they may still contain valuable compounds. This study aims to optimize the extraction of polyphenols from spent black tea (SBT) and spent green tea (SGT) leaves while also exploring their antioxidant and antibacterial properties. Response surface methodology was utilized to determine the optimal experimental conditions for extracting polyphenols from SBT and SGT. The total phenolic content (TPC) was quantified using the Folin-Ciocalteu method, while antioxidant activity was evaluated through the DPPH assay. Antibacterial activity was assessed using the disk diffusion method. Additionally, high-performance liquid chromatography (HPLC) was employed to analyze the phytochemical profiles of the SBT and SGT extracts. Optimal extraction for SBT achieved 404 mg GAE/g DM TPC and 51.5% DPPH inhibition at 93.64 °C, 79.9 min, and 59.4% ethanol-water. For SGT, conditions of 93.63 °C, 81.7 min, and 53.2% ethanol-water yielded 452 mg GAE/g DM TPC and 78.3% DPPH inhibition. Both tea extracts exhibited antibacterial activity against Gram-positive bacteria, with SGT showing greater efficacy against S. aureus and slightly better inhibition of B. subtilis compared to SBT. No activity was observed against the Gram-negative bacteria E. coli and S. typhimurium. HPLC analysis revealed hydroxybenzoic acid as the main phenolic compound in SBT (360.7 mg/L), while rutin was predominant in SGT (42.73 mg/L). The optimized phenolic-rich extracts of SBT and SGT demonstrated promising antioxidant and antibacterial potential, making them strong candidates for use as natural health boosters in food products.

Antimicrobial Activity of Tea and Agarwood Leaf Extracts Against Multidrug-Resistant Microbes

Emerging multidrug-resistant (MDR) strains are the main challenges to the progression of new drug discovery. To diminish infectious disease-causing pathogens, new antibiotics are required while the drying pipeline of potent antibiotics is adding to the severity. Plant secondary metabolites or phytochemicals including alkaloids, phenols, flavonoids, and terpenes have successfully demonstrated their inhibitory potential against the drug-resistant pathogens. In quest of potential phytochemicals, we selected tea (Camellia sinensis) and agarwood (Aquilaria malaccensis) leaves for antimicrobial activity. Fresh tea leaves were collected in three varieties, namely, BT-6, BT-7, and BT-8, including green tea (nonfermented tea), black tea (fully fermented tea), and agarwood leaves collected from Sylhet region of Bangladesh. This study is aimed at analyzing the phytochemical constituency and antimicrobial activity of tea and agarwood leaf extracts and analyzing if there is a combined effect or synergistic activity against multidrug-resistant pathogens. The antimicrobial activity of tea and agarwood leaf extracts was analyzed against MDR pathogenic bacteria and fungus. Qualitative and quantitative phytochemical constituency profiling of these six leaf extracts was evaluated, and preliminary screening exhibited that most of the leaves contained diverse groups of metabolites (alkaloids, tannin, flavonoids, glycosides, saponins, etc.). The highest amounts of TPC (total phenolic content) (110.16 ± 0.48 μg/mg) were found in BT-7 in ethanol extracts, and BT-8 in methanol extracts possessed the highest (128.1 ± 0.43 μg/mg) TFC (total flavonoid content). Notably, green tea showed remarkable results in TPC and TFC. In antioxidant scavenging activity, BT-7 and green tea showed significant IC50 values which were 13.23 and 20.75 mg/mL, respectively. In antimicrobial assays, both 50 μL of each tea and agarwood leaf extract antimicrobial activities were examined against 50 μL of each bacterial and fungal culture. In synergistic activity, 50 μL of each type of leaf extracts was poured over the commercial antibiotics to evaluate their synergism, additive, or antagonism activity against the multidrug-resistant pathogens. In the antimicrobial activity test, green tea showed a maximum diameter (22.0 ± 1.1 mm) zone of inhibition against Klebsiella pneumoniae whereas BT-8 showed 22.0 ± 2.5 mm against Pseudomonas aeruginosa. Indeed, fresh tea BT-6 and BT-7 both showed remarkable zone of inhibition against the selected microbes including Gram-negative and Gram-positive bacteria. Besides, leaf extract also showed antimicrobial activity against pathogenic fungus Mucor circinelloides. Aiming to increase antibiotic resistance efficacy, synergistic activities were evaluated among leaf extracts and antibiotics against the selected pathogens where synergism, antagonism, and additive results were noted. Combination of BT-8 extracts with antibiotics (ceftiofur) showed the highest synergism nearly 36 mm of the zone of inhibition against Escherichia coli. Additionally, green tea with gentamicin and erythromycin also showed remarkable synergism 35 and 33 mm against Mucor circinelloides and E. coli, respectively. Tea and agarwood leaves grown in Bangladesh possess high antioxidant activity, promising antibacterial and antifungal activity, thus might provide a potential source for drug discovery.

Polyphenols: Secondary Metabolites with a Biological Impression

Polyphenols are natural compounds which are plant-based bioactive molecules, and have been the subject of growing interest in recent years. Characterized by multiple varieties, polyphenols are mostly found in fruits and vegetables. Currently, many diseases are waiting for a cure or a solution to reduce their symptoms. However, drug or other chemical strategies have limitations for using a treatment agent or still detection tool of many diseases, and thus researchers still need to investigate preventive or improving treatment. Therefore, it is of interest to elucidate polyphenols, their bioactivity effects, supplementation, and consumption. The disadvantage of polyphenols is that they have a limited bioavailability, although they have multiple beneficial outcomes with their bioactive roles. In this context, several different strategies have been developed to improve bioavailability, particularly liposomal and nanoparticles. As nutrition is one of the most important factors in improving health, the inclusion of plant-based molecules in the daily diet is significant and continues to be enthusiastically researched. Nutrition, which is important for individuals of all ages, is the key to the bioactivity of polyphenols.

Continuous production machine for separating and shaping Taiping Houkui tea

In response to the challenges of low automation and a lack of a continuous processing system for Taiping Houkui tea, this study proposed a design scheme for a continuous processing line and built a continuous processing prototype for testing by combining the production requirements of Taiping Houkui tea, the characteristics of withered leaves, and the existing relevant production equipment. First, the physical properties of Taiping Houkui tea were determined. A simulation was performed using the Hertz-Mindlin model, and the motion states of the tea leaves were obtained under different conditions to define the parameter design range of the experimental platform and verify its structural rationality. Then, the response surface methodology was used to optimize the working parameter ranges and obtain the best working parameters for the feeding and kneading mechanisms. Finally, a continuous production prototype was constructed for further production verification. The experimental results show that the success rate of continuous production on this platform was 70.68%, with an average output of approximately 0.4 kg/h for Taiping Houkui dry tea on a single slide track, and the produced tea was similar to manually made tea. This demonstrates that the continuous production technique has high feasibility and provides a reference for continuous production of Taiping Houkui tea.

Antibacterial activities of Miang extracts against selected pathogens and the potential of the tannin-free extracts in the growth inhibition of Streptococcus mutans

Bacterial pathogens have remained a major public health concern for several decades. This study investigated the antibacterial activities of Miang extracts (at non-neutral and neutral pH) against Bacillus cereus TISTR 747, Escherichia coli ATCC 22595, Salmonella enterica serovar Typhimurium TISTR 292 and Streptococcus mutans DMST 18777. The potential of Polyvinylpolypyrrolidone (PVPP)-precipitated tannin-free Miang extracts in growth-inhibition of the cariogenic Streptococcus mutans DMST 18777 and its biofilms was also evaluated. The tannin-rich fermented extracts had the best bacterial growth inhibition against S. mutans DMST 18777 with an MIC of 0.29 and 0.72 mg/mL for nonfilamentous fungi (NFP) Miang and filamentous-fungi-processed (FFP) Miang respectively. This observed anti-streptococcal activity still remained after PVPP-mediated precipitation of bioactive tannins especially, in NFP and FFP Miang. Characterization of the PVPP-treated extracts using High performance liquid chromatography quadrupole-time of flight-mass spectrometry (HPLC-QToF-MS) analysis, also offered an insight into probable compound classes responsible for the activities. In addition, Crystal violet-staining also showed better IC50 values for NFP Miang (4.30 ± 0.66 mg/mL) and FFP Miang (12.73 ± 0.11 mg/mL) against S. mutans DMST 18777 biofilms in vitro. Homology modeling and molecular docking analysis using HPLC-MS identified ligands in tannin-free Miang supernatants, was performed against modelled S. mutans DMST 18777 sortase A enzyme. The in silico analysis suggested that the inhibition by NFP and FFP Miang might be attributed to the presence of ellagic acid, flavonoid aglycones, and glycosides. Thus, these Miang extracts could be optimized and explored as natural active pharmaceutical ingredients (NAPIs) for applications in oral hygienic products.

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.

The Changes in Metabolites, Quality Components, and Antioxidant Activity of Tea (Camellia sinensis) Infected with Exobasidium vexans by Applying UPLC-MS/MS-Based Widely Targeted Metabolome and Biochemical Analysis

Blister blight infection with Exobasidium vexans is one of the most destructive foliar diseases that seriously affect the quality and yield of tea. This research investigated the metabolite changes of healthy and infected leaves on tea cultivar 'Fuding Dabaicha' and further explored the potential antimicrobial substances against E. vexans infection. In total, 1,166 compounds were identified during the entire course of an infection, among which 73 different common compounds were significantly accumulated involved in the important antimicrobial substances of flavonoids and phenolic acids, including kaempferol (3,5,7,4'-tetrahydroxyflavone), kaempferol-3-O-sophoroside-7-O-glucoside, phloretin, 2,4,6-trihydroxybenzoic acid, galloylprocyanidin B4, and procyanidin C1 3'-O-gallate, which indicated that these metabolites might positively dominate resistance to E. vexans. Furthermore, relevant biological pathways, such as the flavone and flavonol biosynthesis, flavonoid biosynthesis, and phenylpropane pathways, were more closely related to resistance to E. vexans. Additionally, total flavonoids, phenolics, alkaloids, and terpenoids contributing to antimicrobial and antioxidant capacity were significantly altered during four different infection periods, especially the Leaf_S2 stage (the second stage of infection), in which the most concentration accumulated. The leaves affected by E. vexans infection at the second stage had the relatively highest antioxidant activity. Accordingly, this study provides a theoretical support for and comprehensive insights into the effects on the metabolite changes, tea quality components, and antioxidant activity of blister blight caused by E. vexans.

Pharmacognostic, characterization, physio-chemical scrutinizes, and biological attributes of <i>Goniothalamus wightii</i>

To evaluate the quality control parameters of <i>Goniothalamus wightii</i> leaves, which are used for traditional medicine. The leaves extracts were characterized and to evaluate the phytochemical composition, antibacterial, antibiofilm and antioxidant activities. The macroscopic studies of the leaves are simply arranged, green color and dicot plant. The physico-chemical values are the presence of foreign matter, loss on drying, moisture and tannin content, no swelling and foaming capacity. Total ash, acid-insoluble ash, water soluble ash, and sulphated ash are the ash values; extractive values are examined in various organic solvents with visualized UV to exhibit various color variations. The proximate compositions were fiber, soluble and insoluble fiber, carbohydrates, and lipid content presence at g/100g. The quantitative phytoconstituents presence of hexane, ethyl acetate and methanol extracts such as were resolved in sequential extraction with hexane, chloroform, ethyl acetate, and methanol bands were separated. The FT-IR spectrum resembles the aliphatic and aromatic amines, and the LC-MS were identified by phenolic and flavonoids derivatives, steroids, lignin’s. The compounds based the antioxidant activities were 50-80% inhibition against the free radicals and antibacterial, antibiofilm activities were strongly killed the pathogens (<i>E. coli</i>, <i>E. faecalis</i>). In concluded that the pharmacognostic standardization is the first report in these species. The extracts of <i>G. wightiii</i> have potential antioxidant, antibacterial and antibiofilm effects, which could lead to pharmaceutical and industrial applications.

Combination of HPLC–orbitrap‐MS/MS and network pharmacology to identify the anti‐inflammatory phytochemicals in the coffee leaf extracts

In this study, we investigated the phytochemical compositions and the associated anti‐inflammatory activity of coffee leaf fractions prepared by sequential solvent extraction using high‐performance liquid chromatography–orbitrap‐tandem mass spectrometry (HPLC–orbitrap‐MS/MS) combined with network pharmacology. The results showed that the ethyl acetate fraction (EAC‐L) had the highest nitric oxide (NO), ABTS, and DPPH free radical scavenging abilities due to the higher concentrations of mangiferin, rutin, 3,5‐dicaffeoylquinic acid (3,5‐diCQA), and 4,5‐diCQA. The extraction solvents had the greatest impact on the anti‐inflammatory activity of coffee leaf fractions, whereas the processing method had the most significant effect on the antioxidant activity of these fractions. Untargeted metabolomics analysis using HPLC–orbitrap‐MS/MS indicated that palmitic acid, 3,4‐dihydroxybenzaldehyde, and caffeic acid may be involved in the anti‐inflammatory activity of EAC‐L fraction obtained from fresh coffee leaves. On the other hand, processed coffee leaf fraction exhibited anti‐inflammatory activity that was attributed to the presence of 9S,13R‐12‐oxophytodienoic acid, pinocembrin, and quercetin, which have high degree values associated with the inflammation network. Gene ontology and Kyoto encyclopedia of genes and genomes enrichment of network pharmacology analysis showed that these 35 differential compounds in the coffee leaf fractions affect cell transcription, apoptosis, phosphorylation, NO synthesis, phosphatidylinositide 3‐kinases‐protein kinase B (PI3K‐Akt) signaling pathway, focal adhesion, hypoxia‐inducible factor‐1, hepatitis, cancer, and so on. This result indicated that coffee leaf extract may also function as an inhibitor for inflammation‐related cancers. The findings of our research are valuable in guiding the extraction of anti‐inflammatory components from coffee leaves.

Evaluation of medicinal plants using laser-induced breakdown spectroscopy (LIBS) combined with chemometric techniques

Medicinal plants play a vital role in herbal medical field and allopathic medicine field industry. Chemical and spectroscopic studies of Taraxacum officinale, Hyoscyamus niger, Ajuga bracteosa, Elaeagnus angustifolia, Camellia sinensis, and Berberis lyceum are conducted in this paper by using a 532-nm Nd:YAG laser in an open air environment. These medicinal plant's leaves, roots, seed, and flowers are used to treat a range of diseases by the locals. It is crucial to be able to distinguish between beneficial and detrimental metal elements in these plants. We demonstrated how various elements are categorized and how roots, leaves, seeds and flowers of same plants differ from each other on the basis of elemental analysis. Furthermore, for classification purpose, different classification models, partial least square discriminant analysis (PLS-DA), k-nearest neighbors (kNN), and principal component analysis (PCA) are used. We found silicon (Si), aluminum (Al), iron (Fe), copper (Cu), calcium (Ca), magnesium (Mg), sodium (Na), potassium (K), manganese (Mn), phosphorous (P), and vanadium (V) in all of the medicinal plant samples with a molecular form of carbon and nitrogen band. We detected Ca, Mg, Si, and P as primary components in all of the plant samples, as well as V, Fe, Mn, Al, and Ti as essential medicinal metals, and additional trace elements like Si, Sr, and Al. The result's findings show that the PLS-DA classification model with single normal variate (SNV) preprocessing method is the most effective classification model for different types of plant samples. The average correct classification rate obtained for PLS-DA with SNV is 95%. Moreover, laser-induced breakdown spectroscopy (LIBS) was successfully employed to perform rapid, sensitive, and quantitative trace element analysis on medicinal herbs and plant samples.

Extraction, characterization of polyphenols from certain medicinal plants and evaluation of their antioxidant, antitumor, antidiabetic, antimicrobial properties, and potential use in human nutrition

Introduction

Dietary medicinal plants are among the most sought-after topics in alternative medicine today due to their preventive and healing properties against many diseases.

Aim

This study aimed to extract and determine the polyphenols from indigenous plants extracts, i.e., Mentha longifolia, M. arvensis, Tinospora cordifolia, Cymbopogon citratus, Foeniculum vulgare, Cassia absus, Camellia sinensis, Trachyspermum ammi, C. sinensis and M. arvensis, then evaluate the antioxidant, cytotoxicity, and antimicrobial properties, besides enzyme inhibition of isolated polyphenols.

Methods

The antioxidant activity was evaluated by DPPH, Superoxide radical, Hydroxyl radical (OH.), and Nitric oxide (NO.) scavenging activity; the antidiabetic activity was evaluated by enzymatic methods, and anticancer activity using MTT assay, while the antibacterial activity.

Results

The results showed that tested medicinal plants' polyphenolic extracts (MPPE) exhibited the most significant antioxidant activity in DPPH, hydroxyl, nitric oxide, and superoxide radical scavenging methods because of the considerable amounts of total polyphenol and flavonoid contents. UHPLC profile showed twenty-five polyphenol complexes in eight medicinal plant extracts, categorized into phenolic acids, flavonoids, and alkaloids. The main polyphenol was 3-Feroylquinic acid (1,302 mg/L), also found in M. longifolia, C. absus, and C. sinensis, has a higher phenolic content, i.e., rosmarinic acid, vanillic acid, chlorogenic acid, p-coumaric acid, ferulic acid, gallic acid, catechin, luteolin, 7-O-neohesperideside, quercetin 3,7-O-glucoside, hesperidin, rutin, quercetin, and caffeine in the range of (560-780 mg/L). At the same time, other compounds are of medium content (99-312 mg/L). The phenolics in C. sinensis were 20-116% more abundant than those in M. longifolia, C. absus, and other medicinal plants. While T. cordifolia is rich in alkaloids, T. ammi has a lower content. The MTT assay against Caco-2 cells showed that polyphenolic extracts of T. ammi and C. citratus had maximum cytotoxicity. While M. arvensis, C. sinensis, and F. vulgare extracts showed significant enzyme inhibition activity, C. sinensis showed minor inhibition activity against α-amylase. Furthermore, F. vulgare and C. sinensis polyphenolic extracts showed considerable antibacterial activity against S. aureus, B. cereus, E. coli, and S. enterica.

Discussion

The principal component analysis demonstrated clear separation among medicinal plants' extracts based on their functional properties. These findings prove the therapeutic effectiveness of indigenous plants and highlight their importance as natural reserves of phytogenic compounds with untapped potential that needs to be discovered through advanced analytical methods.

Eco-physiological response of secondary metabolites of teas: Review of quality attributes of herbal tea

Herbal tea is a rich source of secondary metabolites which are reputed to have medicinal and nutritional efficacy. These secondary metabolites are influenced by the abiotic and biotic stresses that improve the production of herbal teas in terms of biomass production, accumulation and partitioning of assimilates of compounds. In this study, various examples of herbal teas have been shown to respond differently to secondary metabolites affected by environmental factors. Thus, the meta-analysis of this study confirms that different herbal teas' response to environmental factors depends on the type of species, cultivar, and the degree of shade that the plant is exposed. It is also evident that the metabolic processes are also known to optimize the production of secondary metabolites which can thus be achieved by manipulating agronomic practices on herbal teas. The different phenolic compound in herbal teas possesses the antioxidant, antimicrobial, antiatherosclerosis, anti-inflammatory, antimutagenic, antitumor, antidiabetic and antiviral activities that are important in managing chronic diseases associated with lifestyle. It can be precluded that more studies should be conducted to establish interactive responses of biotic and abiotic environmental factors on quality attributes of herbal teas.

Ultrasonication Effects on Quality of Tea-Based Beverages

Tea is the most popular consumed drink after water. Teas and tea-based beverages have grown in popularity due to bioactive compounds. Tea-based beverages have started to take their place in the market. Extraction is a crucial step for the production of functional tea-based beverages. Compared to conventional methods, ultrasound is attractive due to its lower energy requirements, and shorter extraction time. This review aimed to discuss recent marketing aspects of tea-based beverages as well as the potential and challenges of a novel infusion technique. This review describes the health benefits and technological aspects of tea-based beverages in relation to how to best solve nutritional and microbial concerns. Current and future challenges and opportunities of the novel infusion technique and its scaling-up for the extraction of bioactive compounds are also covered in the present review.

Tea Plant (Camellia sinensis): A Current Update on Use in Diabetes, Obesity, and Cardiovascular Disease

The tea plant (C. sinensis) has traditionally been consumed worldwide as "tea" for its many health benefits, with the potential for the prevention and therapy of various conditions. Regardless of its long history, the use of tea plants in modern times seems not to have changed much, as the beverage remains the most popular form. This review aimed to compile scientific information about the role and action of tea plants, as well as their status concerning clinical applications, based on the currently available evidence, with a focus on metabolic syndrome, mainly covering obesity, diabetes, and cardiovascular disease. It has been recognized that these diseases pose a significant threat to public health, and the development of effective treatment and prevention strategies is necessary but still challenging. In this article, the potential benefits of tea plants and their derived bioactive components (such as epigallocatechin-3-gallate) as anti-obesity, anti-diabetic, and anti-cardiovascular agents are clearly shown and emphasized, along with their mechanisms of action. However, according to the status of the clinical translation of tea plants, particularly in drug development, more substantial efforts in well-designed, randomized, controlled trials are required to expand their applications in treating the three major metabolic disorders and avoiding the toxicity caused by overconsumption.

Beyond Traditional Use of Alchemilla vulgaris: Genoprotective and Antitumor Activity In Vitro

Alchemilla vulgaris L. (lady's mantle) was used for centuries in Europe and Balkan countries for treatments of numerous conditions and diseases of the reproductive system, yet some of the biological activities of lady's mantle have been poorly studied and neglected. The present study aimed to estimate the potential of A. vulgaris ethanolic extract from Southeast Serbia to prevent and suppress tumor development in vitro, validated by antioxidant, genoprotective, and cytotoxic properties. A total of 45 compounds were detected by UHPLC-HRMS analysis in A. vulgaris ethanolic extract. Measurement of antioxidant activity revealed the significant potential of the tested extract to scavenge free radicals. In addition, the analysis of micronuclei showed an in vitro protective effect on chromosome aberrations in peripheral human lymphocytes. A. vulgaris extract strongly suppressed the growth of human cell lines derived from different types of tumors (MCF-7, A375, A549, and HCT116). The observed antitumor effect is realized through the blockade of cell division, caspase-dependent apoptosis, and autophagic cell death. Our study has shown that Alchemilla vulgaris L. is a valuable source of bioactive compounds able to protect the subcellular structure from damage, thus preventing tumorigenesis as well as suppressing tumor cell growth.

Green Tea (Camellia sinensis): A Review of Its Phytochemistry, Pharmacology, and Toxicology

Objectives Green tea (Camellia sinensis) is a kind of unfermented tea that retains the natural substance in fresh leaves to a great extent. It is regarded as the second most popular drink in the world besides water. In this paper, the phytochemistry, pharmacology, and toxicology of green tea are reviewed systematically and comprehensively. Key findings Green tea has been demonstrated to be good for human health. Nowadays, multiple pharmacologically active components have been isolated and identified from green tea, including tea polyphenols, alkaloids, amino acids, polysaccharides, and volatile components. Recent studies have demonstrated that green tea shows versatile pharmacological activities, such as antioxidant, anticancer, hypoglycemic, antibacterial, antiviral, and neuroprotective. Studies on the toxic effects of green tea extract and its main ingredients have also raised concerns including hepatotoxicity and DNA damage. Summary Green tea can be used to assist the treatment of diabetes, Alzheimer’s disease, oral cancer, and dermatitis. Consequently, green tea has shown promising practical prospects in health care and disease prevention.

Comparative study of phenolic profile, antioxidant and antimicrobial activities of aqueous extract of white and green tea

The sole difference between white tea (WT) and green tea (GT) is the former that made only from the buds and young leaves of the Camelia sinensis plant, whilst the latter is made from matured tea leaves. The phytochemical profiles, phenolic compounds, antioxidant, and antimicrobial activity of two varieties of Camellia sinensis teas, white and green, were compared in this study. Total antioxidant capacity, reducing power, DPPH radical scavenging, and Fe+2 chelating activities were used to determine antioxidant activities in water extract of GT and WT. The largest level of phenolic content was discovered in WGTE compared with the lowest amount was found in WWTE (290.67 mg/100 g tea and 185.96 mg/100 g tea, respectively). Phenoilc acids (gallic, benzoic, chlorogenic, ellagic, and ρ-coumaric acids) and flavonoids (rutin and kampherol) were found in the two extracts. The findings of DPPH radical scavenging assays were 84.06 and 82.37% inhibition. In vitro antimicrobial activity was indicated that (WWTE and WGTE) had a high level of activity against Staphylococcus aureus, and gave negative activity against Salmonella typhimurium, and Aspergillus Niger. The WT and GT extracts are a great source of natural antioxidants with biological effects on human health.

The Influence of Green and Black Tea Infusion Parameters on Total Polyphenol Content and Antioxidant Activity by ABTS and DPPH Assays

Tea contains about 230 chemical bioactive compounds, of which polyphenols represent the most considerable fraction (30% of total dry weight). These compounds have relevant nutritional and pharmacological effects on human health, exerting antioxidant activities against oxidative stress-induced damage. The industrial processes applied in tea production can lead to qualitative and quantitative changes in the phenolic content and composition and in antioxidant properties, thus influencing their potential biological activities. Meanwhile, the procedure for tea preparation may influence the quantity of the extracted phenolic compounds. In this study, the effects of different infusion parameters, such as the water type used for infusion (tap water, distilled water, and natural mineral water), time (3, 5, and 10 min), temperature (T = 80 °C and 100 °C), and pH (ranged between 3 and 9) were considered. The optimal infusion variables resulting from the study were obtained by extracting phenolic compounds at T = 100 °C for 10 min, both for green (916.12–1169.81 mg GAE/g) and black (932.03–1126.62 mg GAE/g) bagged tea samples, respectively.

Phytochemical analysis, antioxidant, cytotoxic, and antimicrobial activities of golden chamomile (Matricaria aurea (Loefl.) Schultz Bip)

Matricaria aurea (Loefl.) Schultz Bip. (Asteraceae), known as golden chamomile, has been traditionally used for the treatment of various diseases. In this study, total phenolic, flavonoid, and tannin contents of total extract and different fractions of this plant were determined. The antioxidant, cytotoxic, and antimicrobial activities were also evaluated. Moreover, the phenolic profiles of selected fractions were determined by HPLC and LC-MS/MS analysis. Results demonstrated total phenolic contents of 37.8-57.2 mg GAE/g and total flavonoid contents of 3.0-111.2 mg QE/g. The ethyl acetate and methanol fractions (EF and MF) had the highest concentrations of phenolic, tannin, and flavonoid compounds. In both DPPH radical scavenging assay and phosphomolybdenum reduction assay, EF showed the best antioxidant activity, followed by MF. EF and MF indicated also the best antibacterial activities against Bacillus subtilis (MIC 1.56 and 12.5 mg ml^-1) and Staphylococcus aureus (MIC 0.78 and 12.5 mg ml^-1). Hexane fraction (HF) had no antibacterial effect. None of the samples had antifungal effect. MTT (3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay revealed for EF and HF the highest antiproliferative activities (IC₅₀ values ranged from 111.8 to 294.6 μg ml^-1). The presence of chlorogenic acid, ferulic acid, and luteolin-7-O-glucoside in MF, and p-coumaric acid in EF was confirmed and quantified.

Comparative Assessment of the Antibacterial Efficacies and Mechanisms of Different Tea Extracts

Tea is a popular beverage known for its unique taste and vast health benefits. The main components in tea change greatly during different processing methods, which makes teas capable of having different biological activities. We compared the antibacterial activity of four varieties of tea, including green, oolong, black, and Fuzhuan tea. All tea extracts showed antibacterial activity and Gram-positive bacteria (Enterococcus faecalis and Staphylococcus aureus) were more susceptible to tea extracts than Gram-negative bacteria (Escherichia coli and Salmonella typhimurium). Green tea extracts inhibited bacterial pathogens much more effectively in all four varieties of tea with the minimum inhibitory concentration (MIC) values at 20 mg/mL, 10 mg/mL, 35 mg/mL, and 16 mg/mL for E. faecalis, S. aureus, E. coli, and S. typhimurium, respectively. Catechins should be considered as the main antibiotic components of the four tea extracts. Total catechins were extracted from green tea and evaluated their antibacterial activity. Additional studies showed that the catechins damaged the cell membrane and increased cell membrane permeability, leading to changes in the relative electrical conductivity and the release of certain components into the cytoplasm. Tea extracts, especially green tea extracts, should be considered as safe antibacterial food additives.

Ethanolic extract of Camellia sinensise licited hypoglycemic but lacked antimalarial properties in Plasmodium berghei-infected diabetic mice

The in vivo antimalarial and antidiabetic activity of extract of Camellia sinensis (ECS) in alloxan-induced diabetic and Plasmodium berghei-infected mice were investigated. Eighty-four BALB/c mice divided into sets 1 & 2 infected with P. berghei and 2 & 3 injected with alloxan received either distilled water, ECS (300mg/kg), Chloroquine (CQ-10mg/kg) or Metformin (250mg/kg). Results showed significant increases (p<0.05) in percentage parasitaemia of P. berghei-infected mice treated with ECS and P. berghei-diabetic mice. Furthermore, ECS significantly decreased (p<0.05) blood glucose and PCV in diabetic and P. berghei-diabetic mice.  ECS regenerated pancreatic islet cells in P. berghei-infected-diabetes but lacked appreciable antimalarial activity.

Structural Characteristics of Crude Polysaccharides from 12 Selected Chinese Teas, and Their Antioxidant and Anti-Diabetic Activities

Twelve representative edible Chinese teas (Camellia sinensis L.) from six categories (dark tea, black tea, oolong tea, white tea, yellow tea, and green tea) were selected in this study. Tea polysaccharides (TPs) were extracted with hot water, and their structural properties and biological activities, mainly antioxidant and anti-diabetic activities, were systematically evaluated. Results revealed that the extraction yields of TPs ranged from 1.81% to 6.38%, and Pu-erh tea polysaccharides had the highest extraction yield (6.38 ± 0.28%). The chemical compositions, molecular weight, and compositional monosaccharides of TPs varied among the six categories of tea. It appeared that all TPs were protein-bound acid heteropolysaccharides, and all TPs exhibited obvious antioxidant and anti-diabetic (e.g., α-glucosidase inhibitory and antiglycation) activities. Particularly, Pu-erh tea polysaccharides also contained the highest total phenolic and protein contents, and also exhibited the best antioxidant and anti-diabetic activities. Moreover, for the structural-function relationship, the heat map analysis found that total phenolic and protein contents in TPs were positively correlated with their antioxidant and anti-diabetic activities, indicating that the presence of phenolic compounds and proteins in the TPs might be the main contributors to their bioactivities. The conclusion from this study can help understand the structural-function relationship of crude tea polysaccharides.

Phytochemical analysis, antioxidant, antibacterial, and cytotoxic activities of leaves and roots of Rubus hyrcanus Juz

Rubus hyrcanus Juz. (Rosaceae), known as Caspian blackberry, is wildly distributed around the Caspian Sea. This study focused on antioxidant, cytotoxic, and antibacterial activities of total extracts and different fractions from the roots and leaves of this species. The total phenolics and flavonoid contents were also evaluated. Finally, the phenolic profiles of selected fractions were determined using HPLC–DAD and LC–MS/MS. The results indicated that the total phenolics content (TPC) of root total extract (RTE) was 3.5 times that of leaves (340.4 and 102.7 mg GAE/g, respectively). The TPC of three root fractions ranged from 226.6 to 392.9 mg GAE/g, while in leaves fractions, it ranged between 68.3 and 101.8 mg GAE/g. The total extract of leaves had higher contents of total flavonoids than roots (70.5 and 8.9 mg QE/g, respectively). The methanol fractions of both parts had the highest amounts of flavonoids. The root methanol fraction (RMF) had the best antioxidant effect in both DPPH radical scavenging assay (IC50: 9.16 μg ml−1) and total antioxidant capacity test (1010.5 mg ɑTE/g). The RMF and RTE had potent antibacterial activities against Bacillus subtilis and Staphylococcus aureus (MIC 1.5 mg ml−1). In the MTT assay, ethyl acetate fractions of roots and leaves exhibited the best cytotoxicity (IC50 247 and 227 μg ml−1, respectively) and the highest selectivity indexes (4.73 and 5.31, respectively). Phytochemical analysis revealed the presence of gallic acid, p-coumaric acid, and chlorogenic acid in leaves ethyl acetate fraction, chlorogenic acid in leaves methanol fraction, and gallic acid in the root ethyl acetate fraction.

Cellular Defensive Mechanisms of Tea Polyphenols: Structure-Activity Relationship

Tea is particularly rich in polyphenols, including catechins and theaflavins, thearubigins, flavonols, and phenolic acids, which are believed to contribute to the health benefits of tea. The health-promoting effects of tea polyphenols are believed to be related to their cellular defensive properties. This review is intended to briefly summarize the relationship between the chemical structures of tea polyphenols and their biological activities. Tea polyphenols appear as direct antioxidants by scavenging reactive oxygen/nitrogen species; chelating transition metals; and inhibiting lipid, protein, and DNA oxidations. They also act directly by suppressing “pro-oxidant” enzymes, inducing endogenous antioxidants, and cooperating with vitamins. Moreover, tea polyphenols regulate cellular signaling transduction pathways, importantly contributing to the prevention of chronic diseases and the promotion of physiological functions. Apparently, the features in the chemical structures of tea polyphenols are closely associated with their antioxidant potentials.

Influence of Seasonal and Yearly Variation on Phenolic Profiles, Caffeine, and Antioxidant Activities of Green Tea (Camellia sinensis (L.) Kuntze) from Azores

This study compares the antioxidant properties (RSADPPH–DPPH radical scavenging activity, FRAP–ferric reducing activity power, and FIC–ferrous ion-chelating activity), the total phenolics (TP), total flavonoids (TF), and catechin profiles, as well as the caffeine content of Azorean Camellia sinensis green tea collected in seasons of two different years. The RSADPPH showed some variation between 2019 and 2020, and presented, in general, better results in 2020 as well as during the summer seasons. The FRAP was also noted to be at its highest in July and August of the two investigated years (6.64 and 6.40 µg/mL in 2019 and 5.85 and 5.46 µg/mL in 2020). According to FIC activity, the August 2019 sample exhibited the highest value (76.18%). The TP varied between 291.14 and 326.93 mg gallic acid equivalents (GAE)/g of dried extract (DE) in 2019 and between 300.25 and 320.58 mg GAE/g DE in 2020. Concerning the TF, the values varied between 51.85 and 67.93 mg rutin equivalents (RE)/g DE in 2019 and between 50.27 and 69.57 mg RE/g DE in 2020. Epicatechins derivatives, determined by HPLC, presented higher values in all samples from 2020 compared to 2019, and the same was observed for esterified catechins. The epigallocatechin-3-gallate content was also higher in all samples from 2020 (214.52–240.16 mg/g DE) compared to 2019 (140.91–210.83 mg/g DE). Regarding caffeine content (12.86–20.45 mg/g DE in 2019 and 13.19–29.35 mg/g DE in 2020), the samples from April and June exhibited similar values in both years. In general, green tea samples exhibited better results in 2020 than in 2019, with the exception of FIC activity, while the varied TP and TF contents in certain months reflect the impact of climatic variation on tea quality.

Ziziphus spina-christi (L.) fortified with Camellia sinensis mediates apoptosis, Notch-1 signaling, and mitigates obesity-induced non-alcoholic fatty liver

The habit of drinking tea is highly prevalent and could be utilized to introduce more health benefits through fortification with medicinal plants. The purpose of this analysis was to assess the nutritional quality and health benefits of fortified Ziziphus tea (ZT) with green tea (GT) against obesity and non-alcoholic fatty liver disease (NAFLD). Proximate analysis and sensory evaluation were carried out on the fortified tea. In the in vivo study, 15 SD rats were used for each group. Flow cytometry was utilized for caspase 3 analysis. ELISA was used for the detection of tumor necrosis factor-alpha and adiponectin levels. Real-time PCR was used to detect Notch-1 and Hes-1 gene expression. The composition of fortified (GT+ZT) showed a significant improvement in the nutritional value represented by the increase in overall protein, crude fat, crude fiber, ash, carbohydrate, mineral contents, and antioxidant capacity. Treatment with GT+ZT restored the disturbance in body weight, lipid profile, liver function, glucose, insulin sensitivity index, and oxidative status. It reversed the changes in TNF-α and adiponectin levels. Their protective effects against NAFLD were indicated by the inhibition of hepatic caspase-3 activity, suppression of Notch-1, and Hes-1 gene expression and amelioration of high-fat diet (HFD)-induced histological alterations. Collectively, our findings, elucidate the precise mechanism of fortified ZT+GT for the attenuation of obesity-induced metabolic disorders and NAFLD via regulating lipolysis, TNF-α, adiponectin, apoptosis, and Notch-1 signaling pathways, and provide a foundation for an easily implemented healthy habit of drinking. PRACTICAL APPLICATIONS: The incorporation of bioactive compounds into functional foods is a growing market. Consumer attention in well-being has increased rapidly toward a fortified diet that provides additional health effects. The fortified (GT+ZT) tea may potentially serve as an easily implemented healthy drinking habit to prevent and manage obesity and NAFLD and reduce the risk of other diseases. Fortification with ZT improved the health-promoting functionality of GT through the enhancement of total protein, carbohydrates, antioxidant, and mineral contents. This was reflected by their synergetic therapeutic activity in ameliorating the disturbance in obesity-related disorders and NAFLD via regulating lipolysis, inflammation, oxidative stress, apoptosis, and Notch-1 signaling pathways. Therefore, (GT+ZT) could be considered functional foods which attribute to functional improvement and reduction in disease risk.

Phytochemical Profile and Antioxidant Properties of Bee-Collected Artichoke (Cynara scolymus) Pollen

The current study intended to determine, for the first time, phenolic and fatty acid profile, antioxidant and certain nutritional properties of monofloral bee-collected artichoke (Cynara scolymus) pollen. Based on UHPLC-DAD MS-MS analysis the main phenolics in extractable fraction were different flavonol glycosides (in particular Isorhamnetin-3-O-glucoside, 49.2 mg/kg of dry weight) while ferulic acid was the predominant phenolic compound (39.4 mg/kg of dry weight) in the alkaline hydrolyzable fraction. Among fatty acids (FAs), results of GC-FID analysis revealed prevalence of unsaturated FAs with cis-5,8,11,14,17-eicosapentaenoic acid (EPA) and oleic acid as the main ones- 28.4% and 24.9%, respectively. Based on the FA composition, nutritional analysis proved that artichoke bee-collected pollen had balanced ω-6 and ω-3 FAs content. To determine the antioxidant properties of pollen, five different assays were applied. It was proved that bioactive compounds in artichoke pollen possessed significant ability to quench DPPH radical as well as ABTS radical cation. In addition, in vitro phosphomolybdenum assay confirmed that artichoke pollen is an excellent source of different antioxidants. Pollen extracts exhibited moderate ferric reducing power as well as low ferrous chelating ability. Some further antioxidant studies (preferably in vivo) should be performed to confirm the observed results.

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.

A Review on the Biological Activity of Camellia Species

Medicinal plants have been used since antiquity to cure illnesses and injuries. In the last few decades, natural compounds extracted from plants have garnered the attention of scientists and the Camellia species are no exception. Several species and cultivars are widespread in Asia, namely in China, Japan, Vietnam and India, being also identified in western countries like Portugal. Tea and oil are the most valuable and appreciated Camellia subproducts extracted from Camellia sinensis and Camellia oleifera, respectively. The economic impact of these species has boosted the search for additional information about the Camellia genus. Many studies can be found in the literature reporting the health benefits of several Camellia species, namely C. sinensis, C. oleifera and Camellia japonica. These species have been highlighted as possessing antimicrobial (antibacterial, antifungal, antiviral) and antitumoral activity and as being a huge source of polyphenols such as the catechins. Particularly, epicatechin (EC), epigallocatechin (EGC), epicatechin-3-gallate (ECG), and specially epigallocatechin-3-gallate (EGCG), the major polyphenols of green tea. This paper presents a detailed review of Camellia species’ antioxidant properties and biological activity.

Estimated Intakes of Nutrients and Polyphenols in Participants Completing the MaPLE Randomised Controlled Trial and Its Relevance for the Future Development of Dietary Guidelines for the Older Subjects

The evaluation of food intake in older subjects is crucial in order to be able to verify adherence to nutritional recommendations. In this context, estimation of the intake of specific dietary bioactives, such as polyphenols, although particularly challenging, is necessary to plan possible intervention strategies to increase their intake. The aims of the present study were to: (i) evaluate the nutritional composition of dietary menus provided in a residential care setting; (ii) estimate the actual intake of nutrients and polyphenols in a group of older subjects participating in the MaPLE study; and (iii) investigate the impact of an eight-week polyphenol-rich dietary pattern, compared to an eight-week control diet, on overall nutrient and polyphenol intake in older participants. The menus served to the participants provided ~770 mg per day of total polyphenols on average with small variations between seasons. The analysis of real consumption, measured using weighed food diaries, demonstrated a lower nutrient (~20%) and polyphenol intake (~15%) compared to that provided by the menus. The feasibility of dietary patterns that enable an increase in polyphenol intake with putative health benefits for age-related conditions is discussed, with a perspective to developing dietary guidelines for this target population.

Effects of Infusion and Storage on Antioxidant Activity and Total Phenolic Content of Black Tea

This study determined antioxidant activity in terms of the 1,1-Diphenyl-2-picrylhydrazyl (DPPH) scavenging ability and total phenolic content of black tea under different infusion and storage conditions. High performance liquid chromatography analysis identified caffeine, (−)-epigallocatechin, (−)-epicatechin-3-gallate, (−)-epigallocatechin-3-gallate and (−)-gallocatechin-3-gallate in the tea sample. The water–tea leaves weight ratio did not affect the DPPH scavenging ability. However, infusion temperature affected the DPPH scavenging activity and the total phenolic content. In the present study, the 50% inhibitory concentrations (IC50) for DPPH of black tea infused at 60 to 100 °C ranged from 100.0 ± 13.7 to 28.4 ± 4.8 μg/mL. The total phenolic content of black tea steeped at 60 to 100 °C ranged from 50.4 ± 5.2 to 178.6 ± 16.4 mg gallic acid equivalent/g dry leaf. Black tea exhibited increased antioxidant activity when the infusion temperature was increased. Regarding short-term storage, the DPPH scavenging ability and total phenolic content of black tea did not significantly change within 15 days. This result was consistent for storage temperatures of 4, 9, and 25 °C.

A Comprehensive Insight on the Health Benefits and Phytoconstituents of Camellia sinensis and Recent Approaches for Its Quality Control

Tea, Camellia sinensis, which belongs to the family Theaceae, is a shrub or evergreen tree up to 16 m in height. Green tea is very popular because of its marked health benefits comprising its anticancer, anti-oxidant, and antimicrobial activities, as well as its effectiveness in reducing body weight. Additionally, it was recognized by Chinese people as an effective traditional drink required for the prophylaxis against many health ailments. This is due to the complex chemical composition of green tea, which comprises different classes of chemical compounds, such as polyphenols, alkaloids, proteins, minerals, vitamins, amino acids, and others. The beneficial health effects of green tea ultimately led to its great consumption and increase its liability to be adulterated by either low-quality or non-green tea products with concomitant decrease in activity. Thus, in this review, green tea was selected to highlight its health benefits and phytoconstituents, as well as recent approaches for its quality-control monitoring that guarantee its incorporation in many pharmaceutical industries. More research is needed to find out other more biological activities, active constituents, and other simple and cheap techniques for its quality assurance that ascertain the prevention of its adulteration.

Natural antioxidants of plant origin

Interest in the content of natural antioxidants in plant-based foods can be from the human health perspective, in terms of how these compounds might help promote one's health and wellness, or from the storage point-of-view, as the endogenous antioxidant constituents aid to extend a foodstuff's shelf-life. This chapter reports essential information about the mechanism of antioxidant action and methods employed for determination of their activity, classes of phenolic compounds (phenolic acids, flavonoids, lignans, stilbenes, tannins), sources of plant antioxidants (oil seeds, cereals, legumes, plants of the Lamiaceae family, tea and coffee, tree nuts, fruits, and berries), extraction strategies of phenolic compounds from plant material, and the influence of processing and storage on the content of natural antioxidants in foods and their antioxidant activity. Thermal processing, if not releasing bound phenolics from the structural matrices of the food, tends to decrease the antioxidant potential or, in the best case scenario, has no significant negative impact. Gentler sterilization processes such as high-pressure processing tend to better retain the antioxidant potential of a foodstuff than thermal treatments such as steaming, boiling, or frying. The impact of processing can be assessed by determining the antioxidant potential of foodstuffs either at the point of formulation or after different periods of storage under specified conditions.