Tea and flavonoids: where we are, where to go next

Arsenic Induced Oxidative Neural-Damages in Rat are Mitigated by Tea-Leave Extract via MMPs and AChE Inactivation, Shown by Molecular Docking and in Vitro Studies with Pure Theaflavin and AChE

BACKGROUND

Chronic arsenic-exposure causes neuromuscular disorders and other health anomalies. Damage to DNA and cytoskeletal/extracellular matrix is brought on by reactive-oxygen-species (ROS)-induced intrinsic antioxidant depletion (thiols/urate). Therapeutic chelating-agents have multiple side-effects.

OBJECTIVES

The protection of (Camellia sinensis) tea-extract and role of uric-acid (UA) or allopurinol (urate-depletor) on arsenic-toxicity were verified in rat model.

METHODS

Camellia sinensis (CS dry-leaves), UA or allopurinol was supplemented to arsenic-intoxicated rats for 4-weeks. Purified theaflavins and their galloyl-ester were tested in-vitro on pure AChE (acetylcholinesterase) and their PDB/PubChem 3-D structures were utilized for in-silico binding studies. The primary chemical components were evaluated from CS-extracts. Biochemical analysis, PAGE-zymogram, DNA-stability comet analysis, HE-staining was performed in arsenic-exposed rat brain tissues.

RESULTS

Animals exposed to arsenic showed symptoms of erratic locomotion, decreased intrinsic antioxidants (catalase/SOD1/uric acid), increased AChE, and malondialdehyde. Cerebellar and cerebrum tissue damages were shown with increased levels of matrix-metalloprotease (MMP2/9) and DNA damage (comets). Allopurinol- supplemented group demonstrated somewhat similar biochemical responses. In the CS-group brain tissues especially cerebellum is considerably protected which is evident from endogenous antioxidant and DNA and cytoskeleton protection with concomitant inactivation of MMPs and AChE. Present study indicates theaflavin-digallate (TFDG) demonstrated the highest inhibition of purified AChE (IC50 = 2.19 µg/ml with the lowest binding free-energy; -369.87 kcal/mol) followed by TFMG (IC50 = 3.86 µg/ml, -347.06 kcal/mol) suggesting their possible restoring effects of cholinergic response.

CONCLUSIONS

Favorable responses in UA-group and adverse outcome in allo-group justify the neuro-protective effects of UA as an endogenous antioxidant. Role of flavon-gallate in neuro protection mechanism may be further studied.

A functional study reveals CsNAC086 regulated the biosynthesis of flavonols in Camellia sinensis

MAIN CONCLUSION

CsNAC086 was found to promote the expression of CsFLS, thus promoting the accumulation of flavonols in Camellia sinensis. Flavonols, the main flavonoids in tea plants, play an important role in the taste and quality of tea. In this study, a NAC TF gene CsNAC086 was isolated from tea plants and confirmed its regulatory role in the expression of flavonol synthase which is a key gene involved in the biosynthesis of flavonols in tea plant. Yeast transcription-activity assays showed that CsNAC086 has self-activation activity. The transcriptional activator domain of CsNAC086 is located in the non-conserved C-terminal region (positions 171-550), while the conserved NAC domain (positions 1-170) does not have self-activation activity. Silencing the CsNAC086 gene using antisense oligonucleotides significantly decreased the expression of CsFLS. As a result, the concentration of flavonols decreased significantly. In overexpressing CsNAC086 tobacco leaves, the expression of NtFLS was significantly increased. Compared with wild-type tobacco, the flavonols concentration increased. Yeast one-hybrid assays showed CsNAC086 did not directly regulate the gene expression of CsFLS. These findings indicate that CsNAC086 plays a role in regulating flavonols biosynthesis in tea plants, which has important implications for selecting and breeding of high-flavonols-concentration containing tea-plant cultivars.

The association between inflammatory and immune system biomarkers and the dietary inflammatory index in patients with COVID-19

Background

Inflammation and cytokine storm have been reported to be the main cause of acute symptoms of coronavirus disease (COVID-19). Diet-induced inflammation may affect the condition of patients with COVID-19. Therefore, this study aimed to investigate the relationship between disease severity, inflammatory and immune system biomarkers, and the dietary inflammatory index (DII) in patients with COVID-19.

Methods

This cross-sectional study was conducted on 500 adult patients with COVID-19. Patients were divided into mild, moderate, and severe conditions based on clinical and laboratory evidence. A validated food frequency questionnaire (FFQ) was used to determine DII and energy-adjusted DII (E-DII) scores. The serum C-reactive protein (CRP) level and blood cell count were measured for all patients. Multiple linear regression was used to explore the association between DII and E-DII and CRP, blood cell counts, and hospitalization in patients with COVID-19.

Results

Coronavirus disease (COVID-19) patients with higher DII had higher consumption of fat and carbohydrate and lower intakes of protein, anti-inflammatory nutrients, garlic, caffeine, tea, onion, and fiber (P < 0.05). There was a positive association between DII and CRP (β = 1.024, P < 0.001), hospitalization (β = 1.062, P < 0.001), WBC count (β = 0.486, P < 0.009), neutrophil count (β = 0.565, P < 0.001), and neutrophil-to-lymphocyte ratio (β = 0.538, P < 0.001) and a negative association between DII and the lymphocyte count (β = −0.569, P < 0.001). There was a positive association between E-DII and hospitalization (β = 1.645, P < 0.001), WBC count (β = 0.417, P < 0.02), and neutrophil-to-lymphocyte ratio (β = 0.35, P < 0.03).

Conclusion

There is a positive correlation between DII and inflammation, immune hyperactivation, and length of hospital stay in patients with COVID-19. Further longitudinal studies are necessary.

The Impact of Dietary Flavonols on Central Obesity Parameters in Polish Adults

Background: Central obesity is defined as the excessive fat tissue located in abdominal region accompanied by systemic inflammation, which drives to cardiovascular disease. Flavonols are antioxidative agents present in food. The aim of this study was investigating the relationship between dietary flavonols intake and central obesity. Methods and results: 80 participants (40 central obese and 40 healthy controls) were administered a food frequency questionnaire dedicated to flavonols intake assessment. Body composition was measured with bioelectrical impedance analysis. The analysis showed significant differences between central obese participants and healthy controls in total flavonol (p = 0.005), quercetin (p = 0.003), kaempferol (p = 0.04) and isorhamnetin (p < 0.001) habitual intake. Among central obese participants, there was a moderate inverse correlation between fat mass (FM) and total flavonol (R = −0.378; 95% CI: −0.620 to −0.071; p = 0.02), quercetin (R = −0.352; 95% CI: −0.601 to −0.041; p = 0.03), kaempferol (R = −0.425; 95% CI: −0.653 to −0.127; p = 0.01) and myricetin intake (R = −0.352; 95% CI: −0.601 to −0.041; p = 0.03). BMI was inversely correlated with total flavonol (R = −0.330; 95% CI: −0.584 to −0.016; p = 0.04) and quercetin intake (R = −0.336; 95% CI: −0.589 to −0.023; p = 0.04). Waist circumference was inversely correlated with total flavonol (R = −0.328; 95% CI: −0.586 to −0.009; p = 0.04), quercetin (R = −0.322; 95% CI: −0.582 to −0.002; p = 0.048) and myricetin intake (R = −0.367; 95% CI: −0.615 to −0.054; p = 0.02). Among flavonols’ dietary sources, there was an inverse correlation between black tea consumption and FM (R: −0.511; 95% CI: −0.712 to −0.233; p < 0.001) and between coffee and waist circumference (R: −0.352; 95% CI: −0.604 to −0.036; p = 0.03) in central obese participants. Conclusions: The higher flavonol intake could play a protective role in abdominal obesity development. What is more, total and selected flavonol dietary intakes are inversely correlated with the parameters used for obesity assessment in central obese participants. The habitual consumption of products rich in flavonols, mainly tea and coffee, could possibly have a preventive role in abdominal obesity development.

An Improved Method of Theabrownins Extraction and Detection in Six Major Types of Tea (Camellia sinensis)

Tea pigments consisting of theabrownins (TBs), theaflavins (TFs), and thearubigins (TRs) affect the color and taste of tea. TBs include a variety of water-soluble compounds, but do not dissolve in n-butanol and ethyl acetate. Previously, the traditional method of TB extraction only mixed tea with n-butanol, and TBs were retained in the water phase. However, without ethyl acetate extraction, TFs and TRs remained in the water phase and affected the detection of TB content. Although an improved method had been devised by adding an ethyl acetate extraction step between tea production and n-butanol extraction, the proportional equation for calculating TB content (%) was not yet developed. In this study, we compared the absorbance at 380 nm (A380) of TB solutions from six major types of tea (green, yellow, oolong, white, black, and dark teas) extracted by improved and traditional methods from the same tea samples. Significantly lower A380 values were obtained from TB solutions via the improved method compared to the traditional method for six major types of tea, and the highest and lowest slops in TB concentrations from A380 analyses were from dark tea and green tea, respectively. Moreover, newly developed equations for TB content in those six tea types extracted by the improved methods were also established.

Changes in Bioactive Compounds, Antioxidant Activities and Chemical Properties of Pickled Tea By-Product Fermentation: Promising Waste Management and Value-Added Product

Pickled tea is an ethnic fermented product produced using Assam tea (Camellia sinensis var. assamica) leaves. It is produced in large quantities every year and the liquid waste from its production is estimated to be up to 2500 mL per every kilogram of pickled tea production. To reduce the waste, pickled tea juice remaining from the process was developed into (1) pineapple kombucha and (2) formulated functional drinks as “value added” products. The juice used for making kombucha was collected at 15 days of pickled tea fermentation due to its high value in antioxidant activity (previous study, 2250 µmol TE per g DW). After fermenting the juice with starter culture, the properties of pineapple kombucha were assessed at 0, 1, 3, 5, 7, 9, 11 days. Results showed that the total phenolic of pineapple kombucha was reduced, while antioxidant assay (FRAP and ORAC) slightly increased. The most suitable fermentation period of pineapple kombucha was at day 3. The formulated drink was made from mixing pineapple kombucha with ginger and lemon juice at various ratios including 100:0:0, 80:10:10 and 80:15:5. The ratio 80:10:10 gave the highest TP and antioxidant activity for the functional drink. In addition, for sensory analysis, liking attribute of 80:15:5 fermented juice kombucha pineapple favor was significantly higher compared to other formulations. The study demonstrates the promising second fermentation process of by-product juice from pickled tea production for the conversion to value-added functional drink with reasonable antioxidant properties.

Flavonoids: Food associations, therapeutic mechanisms, metabolism and nanoformulations

Flavonoids possess an impressive therapeutic potential, thereby imparting them a nutraceutical character. As it becomes increasingly common to consume foods associated with healing properties, it is imperative to understand the associations of different foods with different classes of nutraceutic compounds, and their mechanisms of therapeutic action. At the same time, it is important to address the limitations thereof so that plausible future directions may be drawn. This review summarizes the food associations of flavonoids, and discusses the mechanisms responsible for imparting them their nutraceutic properties, detailing the nuclear factor erythroid 2-related factor 2 (NRF2) signaling pathway, inhibition of inflammatory signaling pathways such as toll-like receptor (TLR), nuclear factor kappa-light-chain-enhancer of activated B cells (NF-kB), cyclooxygenase 2 (COX-2) and lipoxygenase-2 (LOX-2) mediators. Further on, the review explains the mechanism of flavonoids metabolism, reasons for low bioavailability and thereafter recapitulates the role of technological interventions to overcome the limitations, with a particular focus on nanoformulations that utilize the synergy between flavonoids and biocompatible materials used as nanocarriers, as reported in works spanning over a decade. It is the Generally Recognized as Safe (GRAS) classified carriers that will become the basis for developing functional formulations. It is promisingly noteworthy that some flavonoid formulations have been commercialized and mentioned therein. Such commercially viable and safe for consumption technological applications pave way for bringing science to the table, and add value to the innate properties of flavonoids.

Regulation mechanisms of flavonoids biosynthesis of Hancheng Dahongpao peels (Zanthoxylum bungeanum Maxim) at different development stages by integrated metabolomics and transcriptomics analysis

BACKGROUND

Flavonoids have strong free radical scavenging and antioxidant capacity. The high abundance of flavonoids in Chinese prickly ash peels have many benefits to human health. In this study, 'Hancheng Dahongpao', a main cultivar, was taken as materials to investigate the flavonoids biosynthesis mechanism of Zanthoxylum bungeanum Maxim at three key development stages by integration of metabolomics and transcriptomics analysis.

RESULTS

A total of 19 differentially accumulated metabolites were identified, the key flavonoids compounds were kaempferol, quercetin and their glycoside derivatives, and two major anthocyanins (peonidin O-hexoside and peonidin 3-O-glucoside). 5 gene networks/modules including 15 important candidate genes were identified, which was highly correlated with flavonoids. Among these genes, ZM-163828 and ZM-184209 were strongly correlated with kaempferol and quercetin, and ZM-125833 and ZM-97481 were controlled the anthocyanins biosynthesis. Moreover, it was shown that MYB-ZM1, MYB-ZM3, MYB-ZM5, MYB-ZM6 and MYB-ZM7 coordinately controlled flavonoids accumulation through regulating the structural genes.

CONCLUSIONS

Generally, this study systematically revealed the flavonoids metabolic pathways and candidate genes involved in flavonoids biosynthesis and laid a foundation for the potential targets for the breeding of new valuable Chinese prickly ash cultivars.

Tea consumption and the risk of abdominal aortic aneurysm

BACKGROUND

Tea has the potential to lower the risk of abdominal aortic aneurysm (AAA) owing to its high antioxidant capacity. AAA risk factors including smoking, hypertension, and hypercholesterolaemia, may modify this association.

METHODS

The study population included 45 047 men in the Cohort of Swedish Men (COSM) and 36 611 women in the Swedish Mammography Cohort (SMC), aged 45-83 years at baseline. The COSM was established in 1997 with all men who lived in two central Swedish counties (Västmanland and Örebro), and the SMC was established in 1987-1990 with women residing in Västmanland county. Tea consumption was assessed by means of food frequency questionnaires in 1997 and 2009.

RESULTS

During 17.5 years of follow-up, 1781 AAA cases (1496 men, 285 women; 1497 non-ruptured, 284 ruptured) were ascertained via Swedish registers. Tea consumption was inversely associated with total AAA incidence in men and women. Women had a 23 (95 per cent c.i. 8 to 36) per cent lower risk of AAA per each cup per day increment, whereas men had a 9 (0 to 17) per cent lower risk (Pinteraction = 0.029). Tea consumption was associated with a lower risk of both non-ruptured (hazard ratio (HR) 0.93, 95 per cent c.i. 0.85 to 1.01) and ruptured (HR 0.84, 0.71 to 0.98) AAA. Smoking status modified the association (Pinteraction < 0.001), whereby tea consumption was associated with lower risk of AAA in ex-smokers (per cup per day, HR 0.89, 0.80 to 0.98) and in never smokers (HR 0.88, 0.77 to 1.00), but not in current smokers (HR 0.95, 0.84 to 1.06). Tea consumption was associated with a lower risk in participants with (HR 0.88, 0.80 to 0.98) and without (HR 0.93, 0.88 to 1.00) hypertension, and in those with (HR 0.82, 0.67 to 1.01) and without (HR 0.92, 0.86 to 0.98) hypercholesterolaemia.

CONCLUSION

Tea consumption was associated with a reduced risk of AAA. The association was more pronounced for ruptured than non-ruptured AAA, and in patients with hypertension and hypercholesterolaemia than those without. The association was also observed in ex-smokers and never smokers, but not in current smokers.

Tea and its phytochemicals: Hidden health benefits & modulation of signaling cascade by phytochemicals

Tea, one of the most widely consumed beverages, is prepared from the leaves of the Camellia sinensis. The promising health recompenses of tea have been linked to its different phenolic components, which have diverse biological characteristics. Tea also contains several flavonoids, alkaloids, phenolic, theanine, etc., which are associated with anti-oxidant characteristics and a variety of health benefits. It can also lower the pervasiveness of neurological disorders as well as prevent different types of cancer, metabolic syndromes, cardiovascular diseases, urinary stone, obesity, type 2 diabetes. Keeping in mind that tea helps to improve health and prevents many diseases, its consumption has been regarded as a "health-promoting habit" and current medical investigators have established the scientific basis for this concept over time. The current review provides new updated information and perspectives on the tea phytochemicals and their overall health benefits based on molecular processes, experimental studies, and clinical trials.

A Comprehensive Review of the Potential Use of Green Tea Polyphenols in the Management of COVID-19

Green tea is produced from Camellia sinensis (L.) buds and leaves that have not gone through the oxidation and withering processes used to produce black and oolong teas. It was originated in China, but its cultivation and production have expanded to other Eastern Asian countries. Several polyphenolic compounds, including flavandiols, flavonols, flavonoids, and phenolic acids, are found in green tea and may constitute greater than 30% of the dry weight. Flavonols, especially catechins, represent the majority of green tea polyphenols. Green tea polyphenolic compounds have been reported to confer several health benefits. This review describes the potential use of green tea polyphenols in the management of coronavirus disease 2019 (COVID-19). The immunomodulatory, antibacterial, antioxidant, and anti-inflammatory effects of green tea polyphenols have also been considered in this review. In addition to describing the bioactivities associated with green tea polyphenols, this review discusses the potential delivery of these biomolecules using a nanoparticle drug delivery system. Moreover, the bioavailability and toxicity of green tea polyphenols are also evaluated.

Plant Flavonoids: Chemical Characteristics and Biological Activity

In recent years, more attention has been paid to natural sources of antioxidants. Flavonoids are natural substances synthesized in several parts of plants that exhibit a high antioxidant capacity. They are a large family, presenting several classes based on their basic structure. Flavonoids have the ability to control the accumulation of reactive oxygen species (ROS) via scavenger ROS when they are formed. Therefore, these antioxidant compounds have an important role in plant stress tolerance and a high relevance in human health, mainly due to their anti-inflammatory and antimicrobial properties. In addition, flavonoids have several applications in the food industry as preservatives, pigments, and antioxidants, as well as in other industries such as cosmetics and pharmaceuticals. However, flavonoids application for industrial purposes implies extraction processes with high purity and quality. Several methodologies have been developed aimed at increasing flavonoid extraction yield and being environmentally friendly. This review presents the most abundant natural flavonoids, their structure and chemical characteristics, extraction methods, and biological activity.

Preventive Applications of Polyphenols in Dentistry-A Review

Polyphenols are natural substances that have been shown to provide various health benefits. Antioxidant, anti-inflammatory, and anti-carcinogenic effects have been described. At the same time, they inhibit the actions of bacteria, viruses, and fungi. Thus, studies have also examined their effects within the oral cavity. This review provides an overview on the different polyphenols, and their structure and interactions with the tooth surface and the pellicle. In particular, the effects of various tea polyphenols on bioadhesion and erosion have been reviewed. The current research confirms that polyphenols can reduce the growth of cariogenic bacteria. Furthermore, they can decrease the adherence of bacteria to the tooth surface and improve the erosion-protective properties of the acquired enamel pellicle. Tea polyphenols, especially, have the potential to contribute to an oral health-related diet. However, in vitro studies have mainly been conducted. In situ studies and clinical studies need to be extended and supplemented in order to significantly contribute to additive prevention measures in caries prophylaxis.

Aqueous green tea infusion extracted by ultra-sonication method, but not by conventional method, facilitates GLUT4 membrane translocation in adipocytes which potently ameliorates high-fat diet-induced obesity

Green tea contains bioactive compounds, such as polyphenols, responsible for its health-promoting effects, including antiobesity and antidiabetic effects. We previously reported that ultra-sonication extraction (UE) could efficiently increase the extraction yield of green tea compounds. In the present study, we found that the extract obtained using UE contained higher phenolic and flavonoid contents than that obtained using the conventional method. We therefore considered the extract as a bioactive metabolite-rich functional green tea extract (BMF-GTE), and tested its glucose-lowering effect by generating an adipocyte cell line stably expressing 7myc-GLUT4-GFP. We found that BMF-GTE treatment increased GLUT4 translocation to the plasma membrane. Moreover, BMF-GTE administration attenuated weight gain in mice fed a high-fat diet (HFD). Importantly, HFD-induced glucose tolerance was ameliorated in the mice receiving BMF-GTE. Therefore, we conclude that BMF-GTE worked against obesity and diabetes, at least partially, by enhancing GLUT4 translocation in adipocytes. PRACTICAL APPLICATIONS: As green tea is one of the most consumed beverages worldwide, its health effects have been widely tested. In our previous studies, we found that ultra-sonication extraction (UE) has the potential to increase the aqueous extraction yield of green tea compounds compared to conventional extraction techniques. In this study, we examined the biological effect of bioactive metabolite-rich functional green tea extract (BMF-GTE) obtained using UE; we observed that administering BMF-GTE lowered the body weight and increased insulin sensitivity in mice fed a high-fat diet, potentially by facilitating the membrane translocation of GLUT4 in adipocytes. Therefore, this study suggests that the extract obtained with UE had antiobesity and antidiabetic properties, indicative of a potential application of UE in maximizing the beneficial effects of green tea on human health.

Coffee, Black Tea, and Green Tea Consumption in Relation to Plasma Metabolites in an Asian Population

SCOPE

Coffee and tea are among the most popular beverages in the world. However, the association between habitual coffee, green tea, and black tea consumption with metabolomics profiles in Asian populations remain largely unknown.

METHODS AND RESULTS

158 metabolites (14 amino acids, 45 acylcarnitines, and 99 sphingolipids) in the blood plasma of participants are measured from the population-based Singapore Prospective Study Program cohort using mass spectrometry (MS). Linear regression models are used to obtain the estimates for the association between coffee and tea consumption with metabolite levels, adjusted for potential confounders and false discovery rate (FDR). Coffee consumption is significantly associated with higher levels of 63 sphingolipids (29 sphingomyelins, 32 ceramides, a sphingosine-1-phosphate, and a sphingosine) and lower levels of 13 acylcarnitines and alanine. Black tea consumption is significantly associated with higher levels of eight sphingolipids, and lower levels of an amino acid, whereas green tea is significantly inversely associated with four metabolites (C8:1-OH acylcarnitine, ganglioside GM3 d18:1/16:0, sphingomyelins d18:2/18:0 and d18:1/14:0).

CONCLUSIONS

Coffee, black tea, and green tea consumption are associated with plasma levels of certain classes of sphingolipids and acylcarnitines in an Asian population, particularly sphingomyelins, which may mediate the health benefits of these beverages.

Assessing Polyphenol Components and Antioxidant Activity during Fermented Assam Tea Ball Processing

Fermented tea is traditionally consumed in many Asian countries. In Thailand, the product is made by anaerobic submerged fermentation of semi-mature tea leaves before being made into a ball form. This study aims to investigate the composition of health-associated bioactive compounds in fermented tea balls made from Camellia sinensis var. assamica, which is naturally grown in the forests of northern Thailand. The processing involves steaming semi-mature tea leaves followed by anaerobic fermentation in 2% NaCl solution (1:5 w/v of tea leaves solution). Levels of catechin (C), epicatechin (EC), epicatechin gallate (ECG), epigallocatechin gallate (EGCG), gallocatechin (GC), flavonols (myricetin, quercetin, and kaempferol), phenolic acids (caffeic acid, chlorogenic acid, coumaric acid, and sinapic acid), total phenolic content, and in vitro antioxidant activity were evaluated in fresh tea leaves, steamed tea leaves, and fermented tea leaves over a period of 60 days’ monitoring. The results indicated that fermented tea balls still contain significant amounts of tea polyphenols, although their processing may result in some loss of most bioactive compounds. The antioxidant activity measured by Ferric Reducing Antioxidant Power (FRAP), 2,2-diphenyl-1-picrylhydrazyl (DPPH), and Oxygen Radical Absorbance Capacity (ORAC) assays also declined as the fermentation time was extended. However, phenolic acids, including caffeic acid and sinapic acid, contrastingly increased during prolonged fermentation by 74.35% and 171.43% from fresh leaves, respectively.

Disintegration and Dissolution Testing of Green Tea Dietary Supplements: Application and Evaluation of United States Pharmacopeial Standards

Approved performance quality tests are lacking in the United States Pharmacopeia (USP) for dietary supplements (DSs) containing green tea extracts. We evaluated the applicability of USP <2040 > general chapter protocols for disintegration and dissolution testing of botanicals to GT DSs. Of 28 single-ingredient GT DSs tested in 2 to 4 lots, 9 (32.1%) always passed the disintegration test, 8 (28.6%) always failed, and 11 (39.3%) showed inconsistent results. Of 34 multi-ingredient DSs tested in 2 lots, 21 (61.8%) passed and 8 (23.5%) failed in both lots, and 5 (14.7%) exhibited inconsistent performance. When stronger destructive forces were applied (disk added), all of the capsules that had failed initially, but not the tablets, passed. In dissolution testing, for the release of epigallocatechin-3-gallate (EGCG), only 6 of 20 single-ingredient DSs passed. Unexpectedly, with the addition of pepsin (prescribed by USP), only one additional DS passed. These results raise concerns that EGCG was not released properly from GT DS dosage forms. However, the general USP protocols may be inadequate for this botanical. More biorelevant destructive forces may be needed to break down capsules and tablets strengthened by the EGCG's interaction with shell material and to overcome the inhibition of digestive enzymes by EGCG.

Herbal infusions and health

Purpose

Increasingly, interest in and the uptake of herbal infusions has advanced, namely, owing to their bioactive properties and potential links to health. Given this, the purpose of the present review was to collate evidence from human trials for five popular herbal infusions.

Design/methodology/approach

The systematic review comprised ten human trials (560 participants), investigating inter-relationships between herbal infusions consumption and health. Only human studies involving German chamomile (Matricaria chamomilla L. Asteraceae), ginger (Zingiber officinale Roscoe Zingiberaceae), lemon balm (Melissa officinalis L. Lamiaceae), peppermint (Mentha x spicata L. Lamiaceae)/spearmint (Mentha spicata L. Lamiaceae) and rosehip (Rosa canina L. Rosaceae) teas were included in the present paper.

Findings

Most herbal infusions serve as a good source of flavonoids and other polyphenols in the human diet. Studies included in this paper indicate that herbal infusions (1-3 cups tended to be drank daily; infusion rates up to 15 min) could benefit certain aspects of health. In particular, this includes aspects of sleep quality and glycaemic control (German chamomile), osteoarthritic stiffness and hormone control (spearmint), oxidative stress (lemon balm) and primary dysmenorrhea (rosehip).

Research limitations/implications

Ongoing research is needed using homogenous herbal infusion forms, brewing rates and volumes of water to further reinforce these findings. In the meantime, herbal infusions could provide a useful supplementary approach to improving certain aspects of well-being.

Originality/value

The present paper collates evidence from human trials for five popular herbal infusions.

Regulation of color transition in purple tea (Camellia sinensis)

Comparative proteomics and metabolomics study of juvenile green, light purple and dark purple leaf to identify key proteins and metabolites that putatively govern color transition in Camellia sinensis. Color transition from juvenile green to dark purple leaf in Camellia sinensis is a complex process and thought to be regulated by an intricate balance of genes, proteins and metabolites expression. A molecular-level understanding of proteins and metabolites expression is needed to define metabolic process underpinning color transition in C. sinensis. Here, purple leaf growth of C. sinensis cultivar was divided into three developmental stages viz. juvenile green (JG), light purple (LP) and dark purple (DP) leaf. Scanning electron microscope (SEM) analysis revealed a clear morphological variation such as cell size, shape and texture as tea leaf undergoing color transition. Proteomic and metabolomic analyses displayed the temporal changes in proteins and metabolites that occur in color transition process. In total, 211 differentially expressed proteins (DEPs) were identified presumably involved in secondary metabolic processes particularly, flavonoids/anthocyanin biosynthesis, phytohormone regulation, carbon and nitrogen assimilation and photosynthesis, among others. Subcellular localization of three candidate proteins was further evaluated by their transient expression in planta. Interactome study revealed that proteins involved in primary metabolism, precursor metabolite, photosynthesis, phytohormones, transcription factor and anthocyanin biosynthesis were found to be interact directly or indirectly and thus, regulate color transition from JG to DP leaf. The present study not only corroborated earlier findings but also identified novel proteins and metabolites that putatively govern color transition in C. sinensis. These findings provide a platform for future studies that may be utilized for metabolic engineering/molecular breeding in an effort to develop more desirable traits.

Exploiting MATE efflux proteins to improve flavonoid accumulation in Camellia sinensis in silico

Flavonoids in tea plant are the important bioactive compounds for both human health and taste quality. Multidrug and Toxic compound Extrusion (MATE) proteins could improve flavonoid accumulations by transporting and sequestering the flavonoid in vacuoles. We identified 41 putative MATE genes in tea plants. The similar intron-exon structures of tea MATEs clustered within the same gene clade. The correlation analysis of tea flavonoid and transcriptome data showed that TEA006173 might be involve in the tea flavonoid accumulation. The RT-PCR results confirmed that TEA006173 showed high expression in the young leaf tissues. Tertiary structure prediction has shown that TEA006173 contained the 12 helices with three active pockets, comprising 13 critical residues. The present study provided the structural variations and expression patterns of tea MATEs and it would be helpful for taste and nutrient quality improvement in tea plant.

Black tea increases hypertonic stress resistance in C. elegans

Here we identified that BTE (black tea extract), within the studied concentration range, is more effective than GTE (green tea extract) in protecting C. elegans against hypertonic stress, by enhancing survival after exposure to various salts, and alleviating suffered motility loss and body shrinkage. The mechanism of such protection may be due to the ability of black tea to induce the conserved WNK/GCK signaling pathway and down-regulation of the expression levels of nlp-29. Intriguingly, black tea does not relieve hypertonicity-induced protein damage. The findings implicate the potential health benefits of black tea consumed worldwide.

Dietary Supplements: Regulatory Challenges and Research Resources

Many of the scientific and regulatory challenges that exist in research on the safety, quality and efficacy of dietary supplements are common to all countries as the marketplace for them becomes increasingly global. This article summarizes some of the challenges in supplement science and provides a case study of research at the Office of Dietary Supplements at the National Institutes of Health, USA, along with some resources it has developed that are available to all scientists. It includes examples of some of the regulatory challenges faced and some resources for those who wish to learn more about them.

Comparison of Metabolomics Approaches for Evaluating the Variability of Complex Botanical Preparations: Green Tea (Camellia sinensis) as a Case Study

A challenge that must be addressed when conducting studies with complex natural products is how to evaluate their complexity and variability. Traditional methods of quantifying a single or a small range of metabolites may not capture the full chemical complexity of multiple samples. Different metabolomics approaches were evaluated to discern how they facilitated comparison of the chemical composition of commercial green tea [Camellia sinensis (L.) Kuntze] products, with the goal of capturing the variability of commercially used products and selecting representative products for in vitro or clinical evaluation. Three metabolomic-related methods-untargeted ultraperformance liquid chromatography-mass spectrometry (UPLC-MS), targeted UPLC-MS, and untargeted, quantitative 1HNMR-were employed to characterize 34 commercially available green tea samples. Of these methods, untargeted UPLC-MS was most effective at discriminating between green tea, green tea supplement, and non-green-tea products. A method using reproduced correlation coefficients calculated from principal component analysis models was developed to quantitatively compare differences among samples. The obtained results demonstrated the utility of metabolomics employing UPLC-MS data for evaluating similarities and differences between complex botanical products.

The Peroxidation of Leukocytes Index Ratio Reveals the Prooxidant Effect of Green Tea Extract

Despite tea increased plasma nonenzymatic antioxidant capacity, the European Food Safety Administration (EFSA) denied claims related to tea and its protection from oxidative damage. Furthermore, the Supplement Information Expert Committee (DSI EC) expressed some doubts on the safety of green tea extract (GTE). We performed a pilot study in order to evaluate the effect of a single dose of two capsules of a GTE supplement (200 mg × 2) on the peroxidation of leukocytes index ratio (PLIR) in relation to uric acid (UA) and ferric reducing antioxidant potential (FRAP), as well as the sample size to reach statistical significance. GTE induced a prooxidant effect on leukocytes, whereas FRAP did not change, in agreement with the EFSA and the DSI EC conclusions. Besides, our results confirm the primary role of UA in the antioxidant defences. The ratio based calculation of the PLIR reduced the sample size to reach statistical significance, compared to the resistance to an exogenous oxidative stress and to the functional capacity of oxidative burst. Therefore, PLIR could be a sensitive marker of redox status.

Feasibility of including green tea products for an analytically verified dietary supplement database

The Dietary Supplement Ingredient Database (DSID) is a federally funded, publicly accessible dietary supplement database that currently contains analytically derived information on micronutrients in selected adult and children's multivitamin and mineral (MVM) supplements. Other constituents in dietary supplement products such as botanicals are also of interest and thus are being considered for inclusion in the DSID. Thirty-eight constituents, mainly botanicals were identified and prioritized by a federal interagency committee. Green tea was selected from this list as the botanical for expansion of the DSID. This article describes the process for prioritizing dietary ingredients in the DSID. It also discusses the criteria for inclusion of these ingredients, and the approach for selecting and testing products for the green tea pilot study.