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Tea Flavonoids: Their Functions, Utilisation and Analysis
Abstract
The three main categories of tea: green, black and oolong, result from different processing procedures. In recent years tea has attracted more and more attention because of reported health benefits, in particularly as an antioxidant, but also as an anticarcinogenic and antiarteriosclerotic agent. It is generally believed that flavonoids are mainly responsible for these actions. Tea is now consumed throughout the world not just as a popular beverage, but, because its extracts have been prepared in a variety of physical forms, for example, strong infusions, soft extracts and powders, it is now widely available in a range of food, beverage, and toiletry and cosmetic products.
... Many investigations have reported the presence of polyphenols, flavonoids, catechins, alkaloids, amino acids and aromatic compounds in it. [24][25][26] Qualitative analyses of the green tea samples by IR spectra depicted that all the samples contained the characteristic functional groups and structures of polyphenolic compounds, aromatic amines, carboxylic acids, flavonoids and aliphatic compounds which is in accordance with previous studies. Interpreting the 1 H and 13 C NMR spectra of the methanolic extracts of sample green tea products provides additional evidence for the presence of these compounds. ...
... The quality of green tea products can be ensured by its phytochemical analyses to assess its polyphenolic constituents and also by biological assays to ascertain the numerous reported useful pharmacological activities. 9,24 High-quality green tea often contains EGCG levels above 100 mg/g, caffeine content can range from 15 to 30 mg per 8 oz cup, total polyphenol content 150-300 mg/g, flavonoid content above 10 mg/g. 35,36 Bioactive phytochemical analysis of commercial green teas of India shower caffeine ranging between 46-59%. ...
Green tea (Camellia sinensis) is a "non-fermented" tea popular worldwide attributed to its pleasing flavor and beneficial impact on human health. Commercially available green tea products differ in their quality, constituents and health benefits which can be attributed to the variations in the processing methods, geographical factors, and plant parts used. This study aims to compare the phytochemical constituents and biological activity of four commercial green tea brands of Bangladesh (GTE1-4). Methanolic extracts of four marketed green tea products were employed in this study. The functional groups and characteristic peaks of the known chemical entities were determined by IR and 1D-NMR spectroscopy, respectively. Gas chromatography-mass spectroscopy (GC-MS) technique was utilized for the quantitative determination of caffeine and other volatile substances. Antioxidant and antimicrobial properties were assessed using the (2,2-Diphenyl-1-picrylhydrazyl) DPPH free radical scavenging assay and the disc diffusion method, respectively. Finally, the products were tested for their potential cytotoxic effects. Caffeine, gallic acid, (-)-epicatechin, (-)-epicatechin-3-gallate, (-)-epigallocatechin, (-)-epigallocatechin-3-gallate and quinic acid were identified as the major constituents in the qualitative phytochemical analyses. GTE-1 contained the highest concentration of 1,2,3-benzenetriol while caffeine was the most abundant in GTE-2 (96.16%). Majority of the samples exhibited antimicrobial activity against Gram-positive and Gram-negative bacteria at 1000 µg/mL concentration. Sample GTE-1 exhibited a positive cytotoxic effect at 500 µg/mL concentration when tested on HeLa cells. Taken together, the results indicate that methanol extracts of green tea in different commercial products can differ considerably.
... To sustain the relevance of tea, the tea industry has embarked on rigorous investments to promote value addition and product diversification. Tea extract processing techniques have been adopted to preserve the intake of dietary phytochemicals, leading to an ever-increasing demand for tea extracts and isolated tea bioactive molecules in pharmaceuticals, food-grade additives, and well-marketed cosmetic products [3,33,41,42]. Specialty tea type a product diversification process has previously not known to the Kenyan market, such as green, white, purple, yellow, orthodox processed, and oolong teas, are being popularized. ...
Diversification and value addition in tea has received considerable attention in recent past. This has been occasioned by increased tea volumes in the world market, especially the aerated product that has led to over flooding. Additionally, health benefits associated with diversified products such as green tea and extracts has elicited a lot of interests in both the industry and external players in finding out alternative ways of tea consumption. The aim of this study was to determine biochemical composition of the various tea extract products generated at different points of a multistage extraction process. The extraction process consisted of hot distilled water, methylene chloride and ethyl acetate steps. The products of purple, yellow, green, black orthodox teas, matcha and the semi aerated oolong were used as raw materials for the extracts. Total polyphenols content, individual catechins and caffeine content were assayed using UV-spectrophotometer and High Performance Liquid Chromatography-Photo diode array HPLC-PDA. Analysis of variance (ANOVA) was used for statistical purposes to detect significant differences between the extraction methods with the least significant difference (LSD) used to separate the means in the assayed tea samples. Results generated indicated that total polyphenols, individual catechins and caffeine content were significantly different (p≤0.05) in the assayed tea samples. Water extracts showed high total yield (82.2%), while methylene chloride recorded the least (2.63%). Ethyl acetate tea extracts showed high phenolic content that ranged from 11. 4% to78.1%. Ethyl acetate extract was rich in total catechins content (46.6% to 75.9%). Water extracts had significantly (p≤0.05) high amounts of total catechins (12.3% to 27.6%) compared to residual extracts (5.4% to 8.9%) contrary to methylene chloride extracts which had low total catechin contents (1.2% to 4.5%). Caffeine was predominant in methylene chloride tea extracts and ranged from 29.97% to 58.99% pointing to high solvent affinity. Based on this results, ethyl acetate proved to be the ideal solvent for obtaining extract rich in polyphenols, and methylene chloride for isolation of natural caffeine. For high yield of all polyphenols, water was found to be the solvent of choice of tea extracts without regarding the specific class of compound to be isolated. This study confirmed that specialty tea extracts are a promising source of bioactive compounds, suggesting they could be very attractive for use as dietary supplements, cosmetic ingredients and in food industries.
... Phenolic compounds are significant components of tea leaves, comprising 10-30% of the dry weight [4][5][6], but some literature sources indicate that this level can reach up to 36% [7,8]. The predominant compounds are catechins (flavan-3-ols), which account for up to approximately 30% of tea's dry weight [9]. Variations in the tea chemical composition arise from such factors as plant cultivation conditions, geographical location, agricultural methods, and specific plant characteristics such as variety, age, and leaf position on the shoot [10]. ...
Tea is a significant source of flavonoids in the diet. Due to different production processes, the amount of bioactive compounds in unfermented (green) and (semi-)fermented tea differs. Importantly, green tea has a similar composition of phenolic compounds to fresh, unprocessed tea leaves. It consists primarily of monomeric flavan-3-ols, known as catechins, of which epigallocatechin gallate (EGCG) is the most abundant. Thanks to its antioxidant, antiproliferative, and antiangiogenic properties, EGCG has attracted the scientific community’s attention to its potential use in preventing and/or combating cancer. In this review article, we summarize the literature reports found in the Google Scholar and PubMed databases on the anticancer effect of EGCG on selected malignant neoplasms in women, i.e., breast, cervical, endometrial, and ovarian cancers, which have been published over the last two decades. It needs to be emphasized that EGCG concentrations reported as effective against cancer cells are typically higher than those found in plasma after polyphenol administration. Moreover, the low bioavailability and absorption of EGCG appear to be the main reasons for the differences in the effects between in vitro and in vivo studies. In this context, we also decided to look at possible solutions to these problems, consisting of combining the polyphenol with other bioactive components or using nanotechnology. Despite the promising results of the studies conducted so far, mainly in vitro and on animal models, there is no doubt that further, broad-based activities are necessary to unequivocally assess the potential use of EGCG in oncological treatment to combat cancer in women.
... As catequinas totais perfazem de 20-30% do peso seco do chá (Wang et al., 2000); dentre estas se destacam: galatode epigalocatequina (EGCG) de 1,2-18,8%, epigalocatequina (EGC) de 0,1-5,5%, epicatequina (EC) de 0,19-2% e traços (<0,08%) de catequina (Peterson et al., 2005). ...
O chá verde (Camellia sinensis) é amplamente conhecido por suas propriedades terapêuticas, que incluem ação antioxidante, anti-inflamatória e antimicrobiana. Este estudo revisa o uso dessa planta na produção animal, focando em sua influência positiva na saúde e desempenho de diversas espécies, especialmente ruminantes. Os principais compostos bioativos presentes no chá verde, como catequinas e polifenóis, são apontados como promissores para melhorar a resistência a doenças, promover o bem-estar animal e aumentar a eficiência alimentar. Além disso, a utilização de resíduos de chá verde como aditivos alimentares para ruminantes mostra potencial para reduzir as emissões de metano, um importante poluente associado à produção animal. Apesar dos resultados promissores, desafios como a variabilidade na qualidade dos extratos e a baixa biodisponibilidade das catequinas em ruminantes limitam sua aplicação prática. Estudos in vitro sugerem efeitos positivos na modulação da fermentação ruminal e no desempenho dos animais, mas pesquisas in vivo ainda são necessárias para validar essas conclusões. O chá verde surge, portanto, como uma alternativa viável para substituir promotores de crescimento convencionais, mas sua aplicação ainda demanda ajustes para otimizar seus benefícios no campo.
... Many of the hydroxyl groups of flavonoids lose one hydrogen atom during the fermentation, forming a semiquinone radical with an unpaired electron on the oxygen atom (Kim 2008). Since the galloflavanols have a trio of hydroxides on the B ring, they are considered to be less resistant to oxidation during storage (Wang et al. 2000;Yoshioka et al. 1991). This is because gallo-flavanols are more readily generated as radicals. ...
Meteorological and edaphic factors significantly affect the first flush metabolite composition of Darjeeling tea, impacting flavor, nutrition, and customer preferences. The Camellia sinensis var. sinensis grown in the Darjeeling hills was sampled at different stages of processing. 75 metabolites were identified using a GC/MS-based metabolomic and chemometric technique. The study aimed to pinpoint quality markers and create a database for Darjeeling tea authenticity, India’s first geographical indication product. Principal component analysis and partial least squares discriminant analysis revealed changes in tea metabolites during processing, while the chemometric study demonstrated variations in key compounds. Antioxidant activity exhibited significant variations among the samples with final processed showing highest antioxidant potential. The concentration of amino acids increased significantly ( p < 0.05) from fresh tea leaves to the final processed product. Conversely, the content of organic acids, inorganic acids, and fatty acids was observed to decrease. Additionally, caffeic acids, epicatechin, epigallocatechin, chlorogenic acid, 3, 4-dihydroxybenzoic acid, and 4-hydroxycinnamic acid increased in concentration, while catechin, (-)-epicatechin, gallic acid, pyrogallol, quinic acid, shikimic acid, and arbutin decreased significantly in concentration in the final processed tea. Meteorological parameters were documented during the study period, showing variation in the levels of PM 2.5 , PM 10 , O 3 , NO 2 , and SO 2 . The findings of this study offer insightful information on the variables influencing Darjeeling tea metabolite composition, which tea producers and processors can use to raise the standard and authenticity of this beverage.
Graphical abstract
... Also, purple tea has less caffeine than other teas, such as green tea. The research on it has been extensive regarding its potential benefits for cancer prevention, weight reduction, and cognitive function [22]. It is characterized by a grassy, vegetal taste and can be a little astringent [23]. ...
Purple tea (Camellia sinensis var. assamica) is a distinct variety of Camellia sinensis known for its bioactive compounds, including caffeine, catechins, and a unique compound called 1,2-di-Galloyl-4,6-Hexahydroxydiphenoyl-β-D-Glucose, (GHG) found predominantly in purple tea leaves, which shows potential in obesity management. Studies have indicated that these bioactive compounds play a significant role in reducing BMI and body weight among obese patients. This review focuses on how GHG impacts body weight and BMI in obese patients. A comprehensive literature review was conducted using Science Direct, Semantic Scholar, Wiley, PubMed, and Google Scholar databases up to 2024. The search employed both single keywords (e.g., 'purple tea', 'GHG', 'obesity') and multiple keyword combinations (e.g., 'purple tea and obesity', 'GHG and weight loss') related to purple tea, GHG, obesity, BMI, and clinical studies. The database search yielded 246 articles, with 173 articles retained after removing duplicates and studies published before 1999. This systematic approach aimed to gather comprehensive data on the phytochemistry, pharmacology, and potential therapeutic applications of purple tea. The investigation revealed that GHG operates through multiple mechanisms, such as inhibiting pancreatic lipase to reduce fat absorption, suppressing adipogenesis and lipogenesis, and preventing fatty tissue formation. Clinical investigations demonstrated significant reductions in BMI, waist circumference, and body weight among individuals consuming purple tea extracts with high GHG levels. Additional metabolic benefits include increased energy expenditure, improved insulin sensitivity, and enhanced glucose metabolism regulation. While more comprehensive research is needed to fully elucidate the optimal dosage and long-term effects, current evidence suggests that GHG from purple tea could be a valuable natural intervention in the multifaceted approach to obesity management.
... Chemical element analysis demonstrated that catechins represent a significant amount of the polyphenol content in fresh tea leaves, accounting for 60% to 70% of the total [12]. According to the research, the miang production process yields mostly flavonoids and polyphenols in its byproducts, which include fermented goods, wastewater, and fresh leaves [13]. Similar to other types of tea, these polyphenols include catechin and catechin derivatives, but the concentrations of the active components in each variety of tea differ significantly [10]. ...
Obesity, a major global health concern, is represented by an accumulation of adipose tissue and body mass, leading to a higher incidence of non-communicable diseases (NCDs). Camellia sinensis var. assamica, known as cha-miang, contains catechin and its derivatives, which have been reported to affect several health-related concerns such as anti-cancer, anti-inflammatory, anti-hyperlipidemia, and against cardiovascular disease. The research aimed to examine the anti-obesity and insulin resistance effects of fresh cha-miang extract (CME) and fermented cha-miang extract (FCME), and to investigate the anti-obesity and anti-diabetic effects of CME and FCME in obese rats generated by a high-fat diet. The extracts demonstrated significant antioxidant potential, with CME demonstrating greater DPPH radical scavenging activity, whereas FCME excelled in ABTS radical scavenging. In the animal model, CME and FCME significantly reduced body weight, plasma insulin levels, insulin resistance, and accumulation of fat compared to the obese control group. Moreover, plasma biochemical analysis indicated that both extracts enhanced lipid profiles by reducing cholesterol, triglycerides, and LDL-cholesterol levels, while elevating HDL-cholesterol. Histological analysis revealed decreased hepatic fat accumulation, especially when extracts were concurrently treated with metformin. The research indicates that CME and FCME, especially in conjunction with metformin, have potential anti-obesity and anti-insulin resistance benefits attributed to their abundant polyphenolic content and antioxidant characteristics. This indicates that cha-miang may serve as an effective option for the management of obesity and metabolic diseases.
... Tea is known for its various favors, aromas, and health benefts and is consumed in several diferent forms, such as green, black, or oolong tea. Green tea leaves predominantly contain the catechin epigallocatechin gallate (EGCG) (40%-69%), followed by epigallocatechin (EGC) (12%-23%), epicatechin gallate (ECG) (13%-21%), and epicatechin (EC) (5%-9%) [1][2][3]. Nonetheless, these ratios may difer depending on factors such as environmental conditions, type of tea, and agricultural methods such as harvest timing and the age of the leaves [4,5]. In addition, younger leaves contained greater amounts of EGCG and ECG when compared to older leaves, while the mature (MT) leaves exhibited higher levels of EGC and EC. ...
Tea is a rich source of phytochemicals; their composition in tea extracts varies depending on the cultivar, climate, production region, and processing and handling processes. The method of extraction plays a crucial role in determining the biological effects of the bioactive compounds in tea leaves. However, reports on the catechin profiles and antioxidant activities of the extracts obtained from leaves at different stages of maturity are limited. Here, we aimed to evaluate the effect of ultrasound-assisted extraction (UAE) and different drying methods, freeze drying (FD) and spray drying (SD), on the composition of bioactive compounds, phenolic composition, and antioxidant activity of extracts obtained from different part of leaves, top (TT), middle (ML), and mature (MT), of Assam tea cultivar (Camellia sinensis var. assamica) cultivated in Thailand (Thai Assam tea). High-performance liquid chromatography analysis showed that the extracts obtained by UAE with FD from TT leaves (UAEFD-TT) had the highest catechins (341.38 ± 0.11 mg/g extract) and caffeine (93.20 ± 0.36 mg CF/g extract) contents compared with those extracted from ML and MT using the same method as well those obtained by SD. The total phenolic and total flavonoid contents were the highest in UAEFD-TT extracts (456.78 ± 4.31 mg GAE/g extract and 333.98 ± 0.83 mg QE/g extract, respectively). In addition, UAEFD-TT exhibited the highest antioxidant activity; the IC50 values obtained by 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assays were 1.31 ± 0.02 and 7.51 ± 0.03 μg/mL, respectively. In the ferric-reducing antioxidant power (FRAP) assay, the UAEFD-TT extract demonstrated the highest antioxidant activity (324.54 ± 3.33 μM FeSO4/mg extract). These results suggest that extraction from TT using UAE followed by FD produced the highest amount of antioxidant compounds in Thai Assam tea extracts.
... Scientific investigations also indicated that both black and green tea polyphenols have antibacterial activity against both gram-positive and gram-negative bacteria (Toda et al., 1990;Hamilton-Miller, 1995;Tiwari et al., 2005;Almajano et al., 2008;Bancirova, 2010). Regular consumption of green tea, which helps inhibit oral bacteria, may be able to prevent tooth decay to some extent, according to Wang et al. (2000). ...
... Scientific investigations also indicated that both black and green tea polyphenols have antibacterial activity against both gram-positive and gram-negative bacteria (Toda et al., 1990;Hamilton-Miller, 1995;Tiwari et al., 2005;Almajano et al., 2008;Bancirova, 2010). Regular consumption of green tea, which helps inhibit oral bacteria, may be able to prevent tooth decay to some extent, according to Wang et al. (2000). ...
... This is because the enzymatic oxidation process in black tea may result in the degradation of a significant portion of the catechin components. The findings of this study align with the findings of Wang et al. (2000), who discovered that the catechin content of tea is a significant factor in determining its bitterness and astringency. The low catechin content of the Solanum herbal infusions is responsible for low astringency and after taste results recorded in Table 1. ...
Herbal teas are ingested for various purposes and by diverse populations across the globe. There is a growing recognition among individuals of the advantages associated with the use of this beverage, leading to a heightened demand for the manufacture of herbal tea derived from therapeutic plants. Spices on the other hand add flavour to food but could pose harm if it is high in phytates and oxalates. The objective of this study was to develop natural spices and herbal tea with health beneficial properties using Solanum nigrum and Solanum torvum berries. Herbal tea samples from S. nigrum were prepared by sorting berries, maceration, divided into two (fermenting at 18 °C and non-fermenting) and dried at 60 °C for 12 h in a hot oven. Spices from S. torvum and S. nigrum were prepared by removing the berries from the stalk, freeze-drying and smooth milling into fine powder. In addition, antinutrient, phytochemical and sensory evaluation studies were conducted on these spices and herbal teas. A nine-point hedonic scale was utilized for the purpose of conducting a consumer acceptability sensory evaluation test using 101 untrained panelists. Data was then analyzed by t-test, one-way analysis of variance (ANOVA) and the level of significance (p < 0.05) was assessed using Tukey's and Dunnett's multiple comparison tests. The panellists expressed a favourable perception towards Solanum nigrum unripe unfermented green herbal tea (6.65 ± 2.08) as compared to the other formulated teas due to the components working together in a way that produces a nice tea sample. Both Solanum nigrum and Solanum torvum spices contained various levels of catechins, saponins, flavonoids, oxalates, phytates and tannins comparable to literature. The herbal tea samples exhibited a range of catechin content, varying from 0.255 to 0.756 mg/g. The antioxidant activity of the various herbal tea samples ranged from 66.37 ± 0.24 to 78.53 ± 0.18 µg/mL GAE as determined by the DPPH free radical assay Fermented black herbal teas recorded higher total phenols (2.80 ± 0.09 d ), total flavonoids (21.84 ± 1.84 c ) and showed greater antioxidant activity (78.53 ± 0.18 a ) as compared to the unfermented green herbal teas. The process of fermentation resulted in a decrease in pH from 7.22 to 6.53 within a period of 12 h. The Total Titratable Acidity (TTA) grew as the fermentation period progressed, whereas the Total Soluble Solids (TSS) decreased. Phytates were the least antinutrients among the two Solanum species accounting for 0.02 mg/100 g and 0.03 mg/100 g in S. torvum berries (STBs) and ( S. nigrum berries) SNBs respectively.
... In these leaves, the predominant compounds are three aglycone flavonoids (quercetin, kaempferol, and apigenin) and two glycosylated flavonoids (rutin and quercitrin) [31]. However, it is anticipated that the concentration of flavonoids in C. japonica leaves is higher than in the flowers due to the extensive body of research emphasizing tea leaves (produced from various Camellia sp.) as a rich source of flavonoids [32,33]. ...
Citation: Pereira, A.G.; Fraga-Corral, M.; Silva, A.; Barroso, M.F.; Grosso, C.; Carpena, M.; Garcia-Perez, P.; Perez-Gregorio, R.; Cassani, L.; Simal-Gandara, J.; et al. Unraveling the Bioactive Potential of Camellia.es (A.G.P.); mprieto@uvigo.es (M.A.P.) † These authors contributed equally to this work. Abstract: In recent years, the search for novel natural-based ingredients by food and related industries has sparked extensive research aimed at discovering new sources of functional molecules. Camellia japonica, traditionally known as an ornamental plant, has gained attention due to its diverse array of bioactive compounds with potential industrial applications. Although C. japonica flowers are edible, their phytochemical profile has not been thoroughly investigated. In this study, a phenolic profile screening through an HPLC-ESI-QQQ-MS/MS approach was applied to C. japonica flower extracts, revealing a total of 36 compounds, including anthocyanins, curcuminoids, dihydrochalcones, dihydroflavonols, flavonols, flavones, hydroxybenzoic acids, hydroxycinnamic acids, isoflavonoids, stilbenes, and tyrosols. Following extract profiling, their bioactivity was assessed by means of in vitro antioxidant, antimicrobial, cytotoxic, and neuroprotective activities. The results showed a multifaceted high correlation of phenolic compounds with all the tested bioactivities according to Pearson's correlation analysis, unraveling the potential of C. japonica flowers as promising sources of nutraceuticals. Overall, these findings provide insight into the valorization of C. japonica flowers from different unexplored cultivars thus diversifying their industrial outcome.
... There are records of its consumption as early as 1500 BCE in the Yunnan province of China [2], where it first appeared as a medicinal drink due to the antioxidant, diuretic and anti-inflammatory properties of Camellia Sinesis [3,4] the plant commonly known as tea. The particular variety of tea produced varied greatly depending on the harvesting process and the treatment applied to it [5,6]. However, it was not until the 16th century that its consumption became popular in the West, where it became the emblematic hot drink in the United Kingdom [7,8]. ...
... Both DPPH and FRAP tests carried out to assess the level of antioxidant activity showed that A. herbaalba had moderate antioxidant activity [60]. It appears in the literature that the antioxidant activity is related to the content of phenolic compounds [61], and some studies have already shown that the antioxidant powers of some plants are due to the presence of lowmolecular-weight phenolics, in particular flavonoids, which are effective antioxidants [62]. This survey shows a remarkable percentage of total polyphenols and flavonoids for both the ethanolic (presence of Quercetin obtained by HPLC analysis) and aqueous extracts, which explains the moderate results obtained by the DPPH test. ...
Artemisia herba-alba Asso is an endemic plant from NorthEast Morocco offering a diverse range of pharmacological , cosmetic, and agro-ecological uses. However, Artemisia herba-alba has not been well exploited in the field of plant protection (post-harvest diseases). This is why the main objective of the present study is to evaluate the antifungal and antioxidant activities of extracts or the essential oil of this plant. Antifungal activity was assessed against Botrytis cinerea, Penicillium expansum, and Penicillium digitatum using the agar dilution method for the aqueous extracts and fumigation for the essential oil. Antioxidant activity was assessed using the DPPH scaven-ging test and the FRAP ferric ion reduction capacity. The chemical composition of the extracts was determined by HPLC and that of the essential oil by GC-MS/MS. In addition, the polyphenol, flavonoid, and tannin content was determined using colorimetric methods. The results of this study showed that the total content of polyphenols (217.60 mg GAE/g E), flavonoids (43.59 mg QE/g E), and tannins (32.58 mg GAE/g E) was significantly higher (p ≤ 0.05) in the ethanolic extract than in the aqueous and hexanoic extracts. Moreover, the HPLC analysis of the aqueous extract revealed the presence of six compounds, namely, catechin, gallic acid, hydroxybenzoic acid, syringic acid, caffeic acid, and rutin. In addition, the ethanolic extract was found to contain seven phenolic compounds. On the one hand, 35 compounds were identified in the essential oil of Artemisia herba-alba, representing 99.7% of the total. According to this study, the dominant compounds in the essential oil of Artemisia herba-alba Asso are camphor (46.57%), endo-borneol (5.65%), eucalyptol (5.64%), and thymol (3.85%). Furthermore, the biological evaluation showed that the extracts and essential oil of Artemisia herba-alba have significant antioxidant and antibacterial activities. The findings show that Artemisia herba-alba is a plant that can be used as a source of antifungal chemicals to prevent putrefaction of foodstuffs and, more specifically, postharvest diseases.
... Nowadays tea is one of the most prevalent beverages throughout the world. It is usually made from the leaves of Camellia sinensis (Chen et al. 2000;Wang et al. 2000). Processing of tea is very common around the whole globe, based on the processing procedure, it has been divided into dark tea (post-fermented by microbe), black tea (fully fermented by oxidising enzyme), oolong tea (semi-fermented) and green tea (non-fermented). ...
Cancer, a highly deadly disease, necessitates safe, cost-effective, and readily accessible treatments to mitigate its impact. Theabrownin (THBR), a polyphenolic pigment found in Pu-erh tea, has garnered attention for its potential benefits in memory, liver health, and inflammation control. By observing different biological activities of THBR, recently researchers have unveiled THBR’s promising anticancer properties across various human cancer types. By examining existing studies, it is evident that THBR demonstrates substantial potential in inhibiting cell proliferation and reducing tumour size with minimal harm to normal cells. These effects are achieved through the modulation of key molecular markers such as Bcl-2, Bax, various Caspases, Poly (ADP-ribose) polymerase cleavage (Cl-PARP), and zinc finger E box binding homeobox 1 (ZEB 1). This review aims to provide in-depth insights into THBR’s role in cancer research. This review also elucidates the underlying anticancer mechanisms of THBR, offering promise as a novel anticancer drug to alleviate the global cancer burden.
... Potent infusions are produced by steeping tea leaves in alcohol/water mixtures, while semi-solid concentrates are produced by reducing the water content of the strong infusion to about 20-25%. For tea extract powders or dry extracts, concentrated infusions are transformed through spray drying, leading to solid concentrations of 40-50% (Wang et al., 2000). According to Dwyer & Peterson (2013), flavonoids belong to a group of phenolic compounds commonly encountered in a variety of plant-based foods, with tea standing out for its notably high levels of these compounds. ...
Sacha Inchi leaves may possess antioxidant function which is naturally rich in bioactive ingredients and has been widely processed into herbal teas that has many benefits to human health. According to the global data from the World Health Organization (WHO), there has been a rise in the frequency of diabetes mellitus (DM) among adults. Sacha Inchi tea was prepared using several methods, with green tea not fermented, oolong partially fermented, and black tea completely fermented. The phenolic compounds (total phenolic content (TPC), total flavonoid content (TFC), tannin), free radical scavenging activity (DPPH) and inhibition properties of α-Glucosidase on green, oolong and black Sacha Inchi tea extract were determined. The green Sacha Inchi tea extract displayed the highest TPC and TFC values among the oolong and black Sacha Inchi tea extracts at a concentration of 500µg/mL, with values of 2.10±0.01 µg GAE/mL and 3.23±0.20 µg QE/mL, respectively. Meanwhile, at a concentration of 500µg/mL, Sacha Inchi black tea extract demonstrated strong antioxidant activity by DPPH with radical scavenging activity (%) (89.4±0.45). Furthermore, at a concentration of 15.625 µg/mL, black, oolong, and green tea extracts exhibited stronger inhibitory effects on α-Glucosidase (95%, 95%, 92%, respectively) than acarbose (90%). Therefore, the processing steps involved in tea production impact the phenolic compounds, free radical scavenging activity, and the ability to inhibit α-Glucosidase in green, oolong, and black tea extracts.
Keywords:
α-Glucosidase inhibition; Free Radical Scavenging; Phenolic Compounds; Sacha Inchi leaves; Tea Processing
... The catechins are consequently transformed into intricate secondary metabolites like TFs and TRs. During metabolic processes, young isolated leaves undergo hydrolysis of proteins, fatty acids, glycosides, and other polysaccharides [65,66]. These compounds operate as the substance for the ultimate development of the tea's flavors. ...
Black tea is frequently consumed worldwide and is renowned for having a distinctive scent. The volatile chemicals in tea are responsible for its aroma, which is important for sensory quality. The enzymatic and non-enzymatic processes that produce the compounds endowing black tea with its distinctive aroma are complex. Black tea is well known for its robust and complex aroma, which can vary based on the type of tea leaves used and processing technologies used. During the production of black tea, several intricate biological and chemical processes contribute to the aroma’s development. Different volatile chemicals are generated during the processing of black tea, which includes withering, rolling, fermentation (enzymatic oxidation), and drying. Various methods have been used to analyze and describe the aroma of black tea. Different methods, such as gas chromatography-mass spectrometry, olfactometry, and solid phase extraction, have been used to assess the fragrance of black tea. These methods evaluate characteristics including fruity, flowery, woody, malty, spicy, and smoky flavors. Phenyl ethyl alcohol, one-octen-3-ol, trans-linalool oxide (furanoid), geraniol, and nonanal are major aroma-active compounds in black tea. Sensory analytic techniques are used to assess black tea’s flavor and scent qualities. This assessment helps figure out the tea’s quality, unique characteristics, and even some unpleasant attributes. Black tea is mostly made from Camellia sinensis and Camellia assamica tea varieties. These two varieties, members of the Camellia genus, differ in their development patterns, leaf sizes, and chemical makeup, impacting how black tea’s scent is formed. When evaluating black tea made from Camellia sinensis and assamica, sensory analysis involved assessing the aroma when the tea was dry and, after brewing, noting any differences from other teas. This review focused on how key aromatic compounds are formed during the tea manufacturing process by Camellia sinensis and Camellia assamica black tea.
... Nearly one-third of the favonoids are favonols [11,12]. Flavonols have a hydroxyl group in position 3 of the C ring, which is easy to be glycosylated ( Figure 1) [13,14]. Te glycosylation makes favonols commonly present in plants as glycosides and 3% to 4% of the dry matters of tea are favonol glycosides. ...
A method was established for the determination of 18 flavonoids in tea by ultra-performance liquid chromatography coupled with quadrupole/time-of-flight mass spectrometry (UPLC-Q-TOF/MS). The tea samples were extracted by 70% (V/V) methanol aqueous solution, and separation was achieved on a Kinetex F5 column (2.1 mm × 100 mm, 2.6 μm) with methanol and 0.1% formic acid in water as the mobile phase with a gradient elution. The samples were detected in TOF/MS and information-dependent acquisition (IDA)-MS/MS modes. The results showed that the relative standard deviations of 18 flavonoids were less than 5.0 ppm. The correlation coefficients (R2) of the linear equation were greater than 0.998 in the range of 0.10–200 ng/mL. The limits of detection were 0.0010–0.040 ppm, and the limits of quantification were 0.0020–0.10 ppm. The recoveries ranged from 73.8% to 107% at spiked levels of 0.0020–1.0 ppm, with relative standard deviations (RSDs) being less than 10%. The method was simple, specific, and reliable. It could be used for the rapid screening and quantitative analysis of flavonoids in tea.
... It is a source that provides various health advantages such as antioxidant activity (Anesini et al. 2008), anticancer activity (Butt et al. 2015), and anticarcinogenicity (Yang et al. 2009). Tea has been utilised as a beverage world-wide which contains various phenolic compounds such as catechin (Crespy and Williamson 2004), caffeine (Goto et al. 1996), theanine (Liang et al. 2015), and flavonoids (Wang et al. 2000); catechin is the principal component. Tea residue was utilised to colour the wool/ acrylic blend yarn using various mordants, alum, potassium dichromate, copper sulphate, and ferrous sulphate (Nahar et al. 2020). ...
The demand for natural dyes for imparting sustainable dyeing effects to textiles is increasing. Metal mordants generate an unstainable impact in the natural dyeing of textiles. In order to avoid the toxic effect due to the use of metal mordants, the present work uses enzyme for sustainable natural dyeing of wool. The current study is aimed at preparing multifunctional wool fabric using natural dye green tea (Camellia sinensis). Laccase (an enzyme) was used to polymerise the phenolic compounds of Camellia sinensisin situ on wool. The in situ colouration of wool fabric was performed at various varying dyeing conditions (temperature, time, and concentrations) using laccase. Colouration properties (colour values and strength) were examined to estimate the appearance of dyed fabrics. The evaluation of dyed fabrics for functional properties such as antibacterial, antioxidant, and UV protection was done. The efficient functional properties viz, antibacterial activity (> 75%), antioxidant property (> 90%), and excellent UV protection, were obtained. FTIR analysis of separately prepared polymeric dye and the dyed fabric was also done to confirm the laccase-assisted polymerisation. Thus, a novel approach of enzymatic functional natural dyeing of wool was explored.
... Flavonoids, including flavones, flavonols, anthocyanins and PAs, are important secondary metabolites in dietary and medicinal plants (Wang et al., 2000). Flavonoids are found almost in all plant organs, including roots, stems, leaves, flowers, and fruits. ...
Rubus chingii Hu is a berry plant of the genus Rubus of the Rosaceae family, which has high nutritional and medicinal value and is rich in flavonoids. Flavonol synthase (FLS) and dihydroflavonol 4-reductase (DFR) compete for the common substrate dihydroflavonols to regulate the metabolic flux of flavonoids. However, the competition between FLS and DFR based on enzyme is rarely reported. Here, we isolated and identified two FLS genes (RcFLS1 and RcFLS2) and one DFR gene (RcDFR) from Rubus chingii Hu. RcFLSs and RcDFR were highly expressed in stems, leaves, and flowers, although the flavonol accumulation in these organs was significantly higher than that of proanthocyanidins (PAs). The recombinant RcFLSs demonstrated bifunctional activities via hydroxylation and desaturation at the C-3α position having a lower Michaelis constant (Km) for dihydroflavonols than RcDFR. We also found that a low concentration of flavonols could significantly inhibit RcDFR activity. To investigate the competitive relationship between RcFLSs and RcDFR, we used a prokaryotic expression system (E. coli) to co-express these proteins. The transgenic cells expressing recombinant proteins were incubated with substrates, and the reaction products were analyzed. Furthermore, two transient expression systems (tobacco leaves and strawberry fruits) and a stable genetic system (Arabidopsis thaliana) were used to co-express these proteins in vivo. The results showed that RcFLS1 was dominant in the competition with RcDFR. Our results demonstrated that the competition between FLS and DFR regulated the metabolic flux distribution of flavonols and PAs, which will be of great significance for the molecular breeding of Rubus plants.
... mg/g dw and 3.0-5.86 mg/g dw, respectively [40,41], while lower TF contents were found at levels of 2.69 mg/g dw for oolong tea and 1.15 mg/g dw for pu-erh [41]. These reported TF contents are in accordance with the results of this study. ...
The aims of this research were to optimize the ultrasonic-assisted enzymatic extraction of polyphenols under Miang and tannase treatment conditions for the improvement of antioxidant activity of Miang extracts via response surface methodology. Miang extracts treated with and without tannase were investigated for their inhibitory effects on digestive enzymes. The optimal conditions for ultrasonic-assisted enzymatic extraction of the highest total polyphenol (TP) (136.91 mg GAE/g dw) and total flavonoid (TF) (5.38 mg QE/g dw) contents were as follows: 1 U/g cellulase, 1 U/g xylanase, 1 U/g pectinase, temperature (74 °C), and time (45 min). The antioxidant activity of this extract was enhanced by the addition of tannase obtained from Sporidiobolus ruineniae A45.2 undergoing ultrasonic treatment and under optimal conditions (360 mU/g dw, 51 °C for 25 min). The ultrasonic-assisted enzymatic extraction selectively promoted the extraction of gallated catechins from Miang. Tannase treatment improved the ABTS and DPPH radical scavenging activities of untreated Miang extracts by 1.3 times. The treated Miang extracts possessed higher IC50 values for porcine pancreatic α-amylase inhibitory activity than those that were untreated. However, it expressed approximately 3 times lower IC50 values for porcine pancreatic lipase (PPL) inhibitory activity indicating a marked improvement in inhibitory activity. The molecular docking results support the contention that epigallocatechin, epicatechin, and catechin obtained via the biotransformation of the Miang extracts played a crucial role in the inhibitory activity of PPL. Overall, the tannase treated Miang extract could serve as a functional food and beneficial ingredient in medicinal products developed for obesity prevention.
... There are six types of compounds that can be classified: hydrolyzable flavan-3-ols and its derivatives, theanine, alkaloids, flavonoids, simple phenolics and its 144 compounds, and terpenoids. Flavan-3-ols, e.g., epigallocatechin (EGC), catechin, epicatechin (EC), epicatechin-3-O-gallate (ECG), catechin-3-O-gallate (CG), gallocatechin (GC), gallocatechin-3-O-gallate (GCG), and epigallocatechin-3-gallate (EGCG), are the vital substances of 150 green tea and tea plants [39,40]. Epigallocatechin-3-gallate (EGCG), in particular, has been demonstrated to have properties against VSV in studies. ...
... Catechins are colorless and watersoluble compounds giving bitter harsh taste to green tea. Chemically, they are flavan-3-ol (Wang et al., 2000). Major tea catechins, constituting basic phenolic building stones of green tea, include (−)-epigallocatechingallate (EGCG), (−)-epicatechingallate (ECG), (−)-epigallocatechcin (EGC) and (−)-epicatechin (EC). ...
This study was conducted to investigate the changes encountered in water soluble dry matter (ºBrix), total phenolics, caffeine and some important catechins of green tea extracts extracted through ultrasound-assisted extraction procedures. Extractions were conducted at 70°C temperature, different tea: water ratios (5:100; 10:100) and brewing times (5, 10 and 20 min) and resultant extracts were also supplemented with tannase enzyme. Total phenolics of green tea extracts varied between 2.68 - 3.87 g GAE/100 g dry green tea. The greatest total phenolics (3.87 g GAE/100 g dry green tea) was obtained from 20 min brewing at 70°C and 10:100 tea: water ratio of tannase enzyme-supplemented extract. As compared to the control samples, decreasing EGCG and ECG contents and increasing EGC and EC contents were observed with tannase enzyme supplementations.
Wound healing remains a critical challenge in healthcare, especially with the increasing prevalence of diabetes and its associated complications, such as diabetic foot ulcers (DFUs). Delayed wound healing in diabetic patients is attributed to several factors, with a pathophysiology that is diverse and multifaceted, including decreased immune responses, microvascular dysfunction, oxidative stress and impaired collagen synthesis. Additionally, the development of an infection at the wound site further complicates and hinders the healing process, especially in DFUs. Epigallocatechin gallate (EGCG), a potent bioactive compound found in green tea, has shown promising effects in modulating various stages of wound healing by its antioxidant, anti-inflammatory and anti-bacterial properties in vitro and in vivo. This review discusses delayed wound healing in diabetic wounds, while highlighting the therapeutic potential of GT/EGCG in different stages of wound healing, including in diabetic wounds both in vitro and in vivo. Novel applications such as GT-/EGCG-loaded wound dressings have demonstrated significant positive impacts on wound healings, including in diabetic wounds, both in in vitro and in vivo studies. Despite its therapeutic potential, the commercial application of green tea in wound care faces significant challenges, including issues of bioavailability, stability, cytotoxicity, production costs, the lack of in-depth and complete in vivo studies and, most importantly, the lack of clinical trials. By consolidating current knowledge and identifying gaps, this review aims to inspire future research and innovations in using green tea for effective wound management and potential use in diabetic patients and DFUs, if the positive results from animal in vivo studies are equally effective in human clinical studies.
Green tea possesses antioxidant, anti-inflammatory, anticancer, and antimicrobial activities, reduces body weight, and slows down aging. These effects are primarily attributed to catechins contained in green tea leaves, particularly epigallocatechin-3-gallate. However, in humans, the realization of green tea’s beneficial effects is limited. In order to summarize and critically analyze the available scientific information about green tea’s health benefits and issues related to its use, we conducted an in-depth literature review in scientific databases. A number of in vitro studies reported that green tea catechins modulate various signaling pathways in cells, which is thought to underlie their beneficial effects. However, data on the effects of catechins in humans are scarce, which is partly due to their low stability and oral bioavailability. Furthermore, catechins may also participate in pharmacokinetic interactions when co-administered with certain drugs such as anticancer agents, drugs for cardiovascular diseases, immunosuppressors, etc. As a result, adverse drug reactions or therapy failure may occur. In conclusion, over the years, various approaches have been investigated to optimize catechin intake and to achieve beneficial effects in humans, but to date, the use of catechins for prophylaxis or disease treatment remains limited. Therefore, future studies regarding the possibilities of catechins administration are needed.
ABSTRACT
This study was designed to investigate the production possibilities of basil tea and sherbet using purple basil which is grown in Arapgir, Malatya. Fresh purple basil was used for sherbet production and dried purple basil was used for tea production. There is no sherbet or basil tea production in industrial scale but people make this products for home consumption. The aim of this study was to produce a purple basil tea and sherbet for the industry. Arapgir purple basil was harvested during June-October, 2016 in Arapgir and transferred to Malatya for drying process. The drying processes (semi-shade drying and tray drying) were carried out until the moisture content of the plant was 10 %. For drying purple basil, semi-shade drying and tray drying methods were tested and the results were compared. After the production of basil tea and sherbet, some physical, chemical, biochemical and the sensory analyzes were carried out. Drying processes caused a decrease in color values, while positively affected the total polyphenol and volatile contents of the samples. In terms of color properties and total polyphenol content, it was seen that the basil sherbet was the superior. For the volatile analysis by SPME/GC-MS, it was determined that the samples of tray dried basil tea contained higher levels of volatile compounds than the semi-shade dried basil tea samples. In the SPME/GC-MS analysis, it was found that the volatile organic compounds, 1,8-cineole (eucalyptol), 2-propenoic acid and eugenol were predominant compounds in the basil tea; while linalool, 1,8-cineole and dL-limonene were predominant in the sherbet samples. In sensory analysis performed by the expert panel, the samples of the basil tea and sherbet were preferred. The most favorite sample was the semi-shade basil tea, which contains hibiscus, clove plants and citric acid. It has been concluded that the purple basil plant is suitable for the production of basil tea and sherbet. The tray dried basil tea and sherbet can be produced at industrial scale.
KEYWORDS: Purple basil, herbal tea, sherbet, drying, aroma
Objective
The objective is to develop a natural and stable anti‐oxidative stress and anti‐ageing ingredient. In this study, we evaluated the changes in white tea leaves fermented with Eurotium cristatum PLT‐PE and Saccharomyces boulardii PLT‐HZ and their efficacy against skin oxidative stress.
Methods
We employed untargeted metabolomics technology to analyse the differential metabolites between tea extract (TE) and fermented tea extract (FTE). In vitro, using H 2 O 2 ‐induced HaCaT cells, we evaluated cell vitality, ROS, and inflammatory factors (TNF‐α, IL‐1β, and IL‐6). Additionally, we verified the effects on the extracellular matrix and nuclear DNA using fibroblasts or reconstructed skin models. We measured skin hydration, elasticity, wrinkle area, wrinkle area ratio, erythema area, and erythema area ratio in volunteers after using an emulsion containing 3% FTE for 28 and 56 days.
Results
Targeted metabolomics analysis of white tea leaves yielded more than 20 differential metabolites with antioxidant and anti‐inflammatory activities, including amino acids, polypeptides, quercetin, and liquiritin post‐fermentation. FTE, compared to TE, can significantly reduce reactive oxygen species (ROS) and protect against oxidative stress‐induced skin damage in H 2 O 2 ‐induced HaCaT cells. FTE can inhibit H 2 O 2 ‐induced collagen degradation by suppressing the MAPK/c‐Jun signalling pathway and can also mitigate the reactive oxygen species damage to nuclear DNA. Clinical studies showed that the volunteers' stratum corneum water content, skin elasticity, wrinkle area, wrinkle area ratio, erythema area, and erythema area ratio significantly improved from the baseline after 28 and 56 days of FTE use.
Conclusion
This study contributes to the growing body of literature supporting the protective effects against skin oxidative stress and ageing from fermented plant extracts. Moreover, our findings might inspire multidisciplinary efforts to investigate new fermentation techniques that could produce even more potent anti‐ageing solutions.
Bitki hastalıkları, bitki büyümesini ciddi şekilde etkileyen ve mahsul üretimine zarar veren
önemli bir etken olup, tarımsal gelişmeye karşı sürekli bir tehdit oluşturmuştur. Hastalıklara
dayanım sağlaması ve çevre dostu olması sebebiyle fitokimyasal bileşikler, bitkilerin
metabolizmalarını düzenleyecek şekilde aktive ederek bağışıklık sisteminin dayanıklılığını
artırabilir, bitkide savunma tepkilerini tetikleyebilir ve bitkilerde hastalıklara karşı direnç
kazandırabilir. Bu açıdan alkoloidler flavonoidler, fenoller ve esansiyel yağlar gibi bitki
bünyesindeki fitokimyasal bileşikler büyük önem taşımaktadır. Bu derlemede bu bileşiklerin
bitki hastalıklarındaki antifungal, antibakteriyel ve antiviral mekanizmaları gözden
geçirelecek, bunların uygulamaları ve gelişimleri incelenecektir. Ayrıca bu inceleme
fitokimyasal bileşiklerin bitki hastalıklarına karşı uygulamalarındaki gelişim eğilimlerine ve
uygulama beklentilerine de bir bakış açısı sunacaktır.
Green tea (Camellia sinensis) is a type of unfermented tea that largely retains the natural substance of fresh leaves. It is the second most popular beverage in the world after water. This article examines its historical and contemporary significance and presents some relevant studies. It also describes the ingredients of green tea as well as discussing the physiological and pharmacological effects, relevant side-effects or interactions and possible toxicologies according to their clinical relevance. Studies have shown that the tea polyphenols, with the catechins as the main representatives, have the greatest clinical significance and are pharmacologically active in a variety of ways. Studies have also demonstrated that green tea has antioxidant, anticancer, antibacterial, antiviral, hypoglycemic, cardiovascular and neuroprotective effects. Toxic effects such as hepatotoxicity are very rare and occur mainly at very high doses of green-tea extract and/or in connection with relevant pre-existing conditions or interactions. In summary, studies carried out to date show that green tea and green-tea extracts have an evidence-based efficacy, especially in health care and disease prevention, but they are also increasingly being used successfully in therapeutic applications.
This review compiles diverse plant materials and their phytoconstituents, exploring their potential as antidiabetic agents. It aims to highlight recent advancements in the field, showcasing various plants and their bioactive compounds that have shown promise in managing diabetes.
Pharmacologically screened components from plants like Phyllanthus urinaria, Indigofera tinctoria, Trichosanthes kirilowii, Ziziphus jujuba, Curcuma longa, Gymnema sylvestre, Momordica charantia, Camellia sinensis (green tea), berberine-containing plants, quercetin sources, resveratrol-rich plants, and Allium genus extracts exhibit diverse mechanisms in regulating glucose metabolism. These mechanisms include enhancing insulin sensitivity, stimulating insulin secretion, inhibiting carbohydrate-digesting enzymes, and improving glucose uptake by cells.
Despite the potential benefits of these plant-derived compounds in managing diabetes, challenges arise when incorporating them into antidiabetic products, affecting attributes like color, taste, and texture. Thus, adjustments in processing parameters become essential for effectively integrating these materials into diabetic-friendly products. This review underscores the potential of plant-derived materials in diabetes management while acknowledging the need for further research to optimize their use in developing effective and palatable antidiabetic interventions.
Camellia sinensis (L.) is acknowledged globally as the second most consumed beverage after water. Researchers have dedicated substantial efforts to validate the claims surrounding this plant through rigorous pharmacological screening, aiming to substantiate its traditional applications in treating various ailments. This work extensively delves into aspects such as marketed formulations of green tea, extraction techniques, phytochemistry, pharmacology, interactions between drugs and green tea, and its distinctive characteristics. Key research unequivocally suggests that green tea holds substantial health benefits for individuals. Presently, a multitude of pharmacologically active constituents have been successfully isolated and identified from green tea, encompassing polyphenols, alkaloids, amino acids, polysaccharides, and volatile components. Recent investigations have illuminated the broad spectrum of pharmacological properties exhibited by green tea, encompassing antioxidant, anticancer, hypoglycemic, antibacterial, antiviral, and neuroprotective attributes. The review amalgamates current research findings to present a thorough understanding of the diverse bioactive compounds found in Camellia sinensis, such as polyphenols, catechins, and alkaloids, and their contributions to its health-promoting properties. The review further highlights the significance of extraction techniques in preserving and enhancing the bioactivity of these compounds. Overall, this comprehensive review serves as a valuable resource for researchers, practitioners, and enthusiasts, consolidating the current knowledge surrounding Camellia sinensis and its multifaceted role in promoting human health.
In this study, a stable, selective, reusable, and economic capacitive sensor has been fabricated by implementing molecular imprinted polymer (MIP) technology for the detection of epicatechin (EC) in green tea. A molecular imprinted polydopamine-polyethylene glycol (PDA-PEG) composite deposited on a copper-cladded FR-4 plate is considered the sensing material of the proposed sensor. Scanning electron microscope (SEM) and X-ray diffraction (XRD) techniques were used for the characterization of the synthesized materials. The variation of capacitance
as a function of frequency for MIP-EC capacitive sensor (MIP-EC@C) and nonimprinted polymer-based capacitive sensor (NIP@C) was explored in this study. The linear range of operation was observed at 5–20 ppm with a lower limit of detection (LOD) found to be 1.07 ppb. Two linear regression models were used to predict the EC content of green tea samples. The prediction accuracy of 99.56% is obtained using the principal component regression (PCR) method and that of 99.51% using partial least square regression (PLSR). The root-mean-square error of calibration for both PLSR and PCR was 0.003 using four and five latent variables, respectively. The electrode exhibited a fairly stable behavior, and even after 100 days, the performance of the sensor hardly degraded as only a 0.7% (appropriately) increase in maximum capacitance was observed.
Tea is one of the most ancient and popular therapeutic beverages consumed by people all over the world. It is made from the leaves and buds of the plant "Camellia sinensis". Tea is cultivated in more than thirty countries around the world as a plantation crop. In the present study, tea infusions from twenty black tea samples belonging to low (Dust (I), BOPF, BOPI, OPI, Pekoe), mid (Dust (I), Dust, BOPF Local, BOPI, BOP, OPI, Pekoe) and up (Dust, BOPF, BOP, FBOP, FBOPI, OPA, OPI, Pekoe) country of Sri Lanka were tested by microdilution assay for antibacterial activities against Escherichia coli, Methicillin-resistant S. aureus (MRSA) and M. smegmatis (MS). The results were statistically analyzed using ANOVA. None of the tea infusions showed antibacterial activity against gram-negative bacterium E. coli even at the highest concentration of tea infusion. All the tea samples had antibacterial activity against gram-positive bacteria M. smegmatis and S. aureus. S. aureus was more sensitive to all the tested tea samples than M. smegmatis. Samples with the highest and the lowest antibacterial activity against M. smegmatis were: low-country Dust (I) (MIC-1.24 mg/ml) and mid-country BOPF (MIC-2.78 mg/ml) respectively, while the highest and the lowest antibacterial activity against S. aureus were; mid-country BOP (MIC-0.38 mg/ml) and low-country BOPF (MIC-1.72 mg/ml) respectively. Agro-climatic elevation of the tea sample affected antibac-terial activity of black tea. Based on the results of this study, it is concluded that Sri Lankan black tea possesses selective antibacterial activity against Gram-positive bacterial species and Sri Lankan black tea may have the potential to be used as a safe supplementary beverage during antibacterial therapy.
Green tea is a widely consumed beverage renowned for its numerous positive health effects. However, it is crucial to be cognizant of certain considerations, as excessive consumption can result in adverse outcomes. Green tea offers numerous health benefits; however, certain considerations should be taken into account. Therefore, it is essential for individuals to tailor their green tea consumption based on their specific health status and requirements.
Food allergy is recognized as a global medical problem with increasing prevalence in recent years. Currently, the treatment of food allergy mainly involves avoidance of allergens and allergen-specific immunotherapy. Barring the spontaneous resolution of food allergy during the growth process, this disease is difficult to treat fundamentally. In recent years, the use of functional food ingredients derived from natural products has been attracting attention for their prophylactic use in food allergy. Theaflavins, i.e., black tea polyphenols, are potent antioxidants that have inhibitory effects on a variety of diseases. However, little is known about the preventive effect of theaflavins on food allergy. In this study, we designed a mouse model of food allergy and examined the effect of theaflavins using the severity of diarrhea, a symptom of food allergy, as an indicator. The administration of a black tea extract rich in theaflavins or theaflavin 1 (subgroup of theaflavins) to mice reduced the severity of diarrhea when compared with a normal diet. A reduction in malondialdehyde levels, a key marker of lipid peroxidation, was also observed. Overall, these data suggest that theaflavins may potentially inhibit food allergy by alleviating oxidative stress in the colon and can be a potential food material for prevention of food allergy.
Introduction:
Coffee silver skin (CSS) is a thin covering over green coffee seeds inside coffee cherry. It is a good source of bioactive compounds like chlorogenic acid and caffeine. It is produced as a by-product of the roasting process.
Objective:
The goal of this study is to apply spray drying method to encapsulate 5-O-caffeoylquinic acid (chlorogenic acid) and caffeine extracted from CSS.
Methods:
The main-plots for optimisation were feed solid concentration (2.5, 5, 10°Bx), and the sub-plots of the whole-plot were carrier material type (maltodextrin, modified starch, arabic gum) and inlet air temperature (130, 160, 190°C). Responses included were drying yield, chlorogenic acid concentration, caffeine content, Carr index, and solubility values.
Results:
Suitable conditions were spray drying inlet temperature of 190°C, extract concentration of 10°Bx, and wall material composition [modified starch/arabic gum (MS:AG)] 10.5:9.5. As the feeding CSS extract concentration increased, the amount of chlorogenic acid and caffeine in the final powder increased, while the powder's flow characteristics improved.
Conclusions:
The concentration stage might be used to produce free-flowing powdered particles with good bioactive retention for use in the food processing industry.
Phytonutrients (plant chemicals) called flavonoids may be detected in almost all fruits and vegetables. They are responsible for the brilliant colors of fruits and vegetables, together with carotenoids. Flavonoids, like other phytonutrients, are potent antioxidants with antiinflammatory and immune-enhancing characteristics. Polyphenols may diminish severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) viral infection by linking to the angiotensin-converting enzyme 2 (ACE-2) linking site and limiting viral entrance, as well as regulating the severity of COVID-19 lung destruction by controlling ACE-2 expression. A new potential relationship between SARS-CoV-2 and the co-receptor dipeptidyl peptidase 4 (DPP4) may induce the expansion of newer COVID-19 treatment methods, in addition to ACE-2. After glycosylation, flavonoids' solubility in water is significantly enhanced, which increases their pharmacological actions. Antioxidant and antiinflammatory effects have been discovered in resveratrol (RSV). Quercetin was discovered to have a possible repressing consequence against SARS-CoV-2 in a computer simulation. Main protease (Mpro) had a significant preference for quercetin. According to a computer study, the flavonoids icariin, myricitrin, naringin, quercitrin, and neohesperidin have a significant interaction potential for transmembrane protease serine 2 (TMPRSS2). The bioavailability improvement of quercetin has also been shown in vivo. The novel nanovesicles exhibited extended drug durability and significant therapeutic impact compared to uncoated ones due to chitosan resistance to stomach acid. This chapter aims to explain the use of flavonoids and other polyphenols against SARS-CoV-2.
Bu çalışmada, Türk kahvesi boyutlarını temsil eden çok ince (47.13-54.64 µm), ince (89.25-119.88 µm) ve ince-orta (248.77-312.23 µm) olmak üzere farklı öğütme derecelerine sahip kahvelerin 5, 25 ve 45 °C’lerde 28 günlük depolama periyodunda (0., 14. ve 28. gün) klorojenik asit miktarı, kafein miktarı ve yağ asidi bileşimi üzerindeki değişim incelenmiştir. Kahvenin biyoaktif özelliklerinden sorumlu bileşenleri olan klorojenik asit ve kafein depolama koşullarına bağlı olarak sırasıyla 1.05-1.38 g/100g KM ve 1.49-1.80 g/100g KM arasında değişmiştir. Kahve örneklerinde başlıca yağ asitleri olarak linoleik asit (%41.86-42.89) ve palmitik asit (%33.23-36.36) belirlenmiş, ayrıca oleik asit (%10.59-11.47), stearik asit (%7.38-8.48) ile iz miktarlarda miristik asit, margarik asit, elaidik asit, cis-11 eikosenoik asit, araşidik asit ve behenik asitler de tespit edilmiştir. Kahve örneklerinin sahip oldukları partikül boyutu ve depolama sıcaklığı farklılığının yağ asidi bileşim oranları üzerinde belirgin bir değişikliğe neden olmadığı, ancak depolama süresi boyunca miktarlarında belirgin azalmalar olduğu gözlemlenmiştir.
The present study was designed to evaluate the anti-microbial activity of sesame oil against selected gram positive and gram negative microorganism. The minimum inhibitory concentration (MIC) study revealed that sesame oil shows that potent MIC value against Salmonella typhi is 10 µl/ml. But, for other organism the MIC values were in the range of 350-500 µl/ml. The sesame oil shows best antimicrobial activity with zone of inhibition range 15-25 mm and also equal with standard Kenamycin (19-40 mm) and also it shows highest zone of inhibition against Sal-monella typhi. From this study it has been concluded that sesame oil exhibited potent antimicrobial activity with selected microbial strains.
Rasa Shastra, one of the Pharmaco-therapeutic branches of Ayurveda where metals,
minerals, poisonous plants and animal products are used after proper processing for internal
administration. Talakeshwara Ras is one of Khalvi rasayanas where Emblica officinalis
(Dhatri) and minerals Arsenic tri sulphide (Haratala) & Borax (Tankana) are the ingredients.
It is indicated for Sarva Kushta at one Masha (1 gm) dose. Anti–Microbial activity of
Talakeshwara Ras was done with an intention to evaluate its efficacy against gram positive
and gram negative bacilli. So an honest attempt has been made to put forth the “Anti –
Microbial activity of Talakeshwara Ras” which had its anti microbial activity against
Staphylococcus aureus and Pseudomonas aeruginosa.
The chemiluminescence (CL) of Ru(phen)32+ was applied to HPLC determination of oxalic acid, which was separated by a C18 reverse-phase column with a mobile phase of 0.02 mol/l NH4Ac, mixed with 0.25 mol/l Ru(phen)32+ and 2.0 mmol/l Ce(SO4)2 (0.08 mol/l H2SO4), and then passed through a homemade CL detector. The reaction of Ce(IV) oxidized Ru(phen)32+ and the oxalic acid emitted light. The detection limit was 6.2×10-6 mol/l for oxalic acid at a S/N ratio of 3, the relative standard deviation for 5 replicate injections of 1×10-3 mol/l oxalic acid standard was calculated as 5.6%, and the linear calibration range was 1×10-5 to 4×10-3 mol/l. The method was successfully applied to determination of oxalic acid in tea.
Flavonoids, commonly occurring antioxidants in foods, have been compared in a dose-response manner with vitamins C and E and beta-carotene and found to be powerful antioxidants using an in vitro lipoprotein oxidation model. This model simulates the oxidation of low-density lipoproteins, which results in atherosclerosis. Of the flavonoids and flavonoid-related compounds, flavonols found in tea are the most powerful natural antioxidants. These results provide a mechanism for the beneficial epidemiological effect of dietary flavonoids on heart disease.
Epidemiologic studies indicated that tea consumption reduces the risk of cardiovascular disease. We assessed the effect of green or black tea consumption on resistance of low-density lipoprotein (LDL) to oxidation ex vivo and on serum lipid concentrations in healthy volunteers. In a 4-wk parallel comparison trial, 45 volunteers consumed 900 mL (6 cups) mineral water, green tea, or black tea/d. Blood samples drawn while subjects were fasting were obtained before and after the study. The effect on resistance of subsequently isolated LDL to oxidation of adding green or black tea extract to plasma was investigated in an in vitro experiment. Consumption of 900 mL (6 cups) green or black tea/d did not affect serum lipid concentrations, resistance of LDL to oxidation, or markers of oxidative damage to lipids in vivo, although consumption of green tea slightly increased total antioxidant activity of plasma. The in vitro experiment showed that resistance of isolated LDL to oxidation increased only after incubation of plasma with very high amounts of green or black tea. These amounts, when converted to tea catechin concentrations, were much higher than those expected in vivo. We conclude that daily consumption of 900 mL (6 cups) green or black tea/d for 4 wk had no effect on serum lipid concentrations or resistance of LDL to oxidation ex vivo. Future research should focus on mechanisms by which tea flavonoids may reduce the risk of cardiovascular disease other than by increasing the intrinsic antioxidant status of LDL.
(1) 緑茶浸出液をセファデックスG-75による液体クロマトグラフィで分画することにより総量90%以上の回収率で5つのフラクションに分けることができる。この場合,カフェイン,アミノ酸類,糖は2つのフラクションにまたがっているが,全体として成分グループ別に分けることができる。苦味,渋味はタンニンの存在するフラクションにあり,しかも,その70～75%はカテキンの存在するフラクションにあること,さらに,フラクション液もしくは緑茶浸出液を除タンニン処理した場合,除タンニン率と苦味,渋味の減少率がよく一致することなどから緑茶の苦味,渋味は主としてタンニンとくにカテキンによるものであることが確認された。(3) 緑茶のうま味,甘茶の70%程度はアミノ酸類,糖などの存在するフラクションにあること,アミノ酸類を除去した場合,うま味が1/3程度に減少することからうま味はアミノ酸によるものが大きく,一方,甘味は多くて半分程度までしか減少しないことから,糖によるのが大きいと推定された。
On the basis of previous findings, the effectiveness of a tea drinking program for caries prevention was tested in the primary schools of two typical Japanese farm villages for five years. Caries lesions on the pit/fissure (CF) and approximal sites (CA) were detected with the point of a No. 1 sewing needle by clinical criteria. The average number of carious lesions in both villages decreased in the first program year and reduction rates were almost constant thereafter. The reduction rates averaged 22.1% in CF and 26.1% in CA.The program was evaluated from three angles, accessibility, availability, and acceptability. The monetary accessibility was considered very good because the above reduction rates were attained by the expense of only 1.5 yen for a cup of Bancha tea. Yearly production of Bancha in Japan would cover about 4.5 times more children.In order to assess the objective acceptability, a new scale called the epidemiological susceptibility of the caries risk (ESF and ESA) was derived from the caries experience (CF and CA) divided by the caries risk which was half the number of existing teeth (D) multiplied by the dentitional age of the permanent teeth (T) of a child. The reduction rate of the susceptibility of the caries risk averaged 19.5% in ESF and 21.3% in ESA respectively. No signs of the mottling such as discoloration and disfiguration of the teeth were found on the lower front teeth.It was stressed that dental caries produced by multifactorial causes should not be prevented by use of a single agent, but accomplished by a combination of multiple anticaries agents in order to avoid overdosage.
To develop a method for determination of tea catechins in food by HPLC with an electrochemical detector, we examined the responses of an electrochemical detector to tea catechins. Five catechins ((+)-catechin, (-)-epicatechin, (-)-epigallocatechin, (-)-epicatechin gallate, (-)-epigallocatechin gallate) started to show a response at the applied potential of +400mV, and the maximum response was observed at about +800mV. The content of tea catechins in food is relatively high, and the sensitivity of the electrochemical detector to tea catechins was about one thousand times higher than that of the UV detector. Generally, an electrochemical detector responds to many substances as the applied potential is increased. We concluded that for the analysis of tea catechins in foods a suitable applied potential of the electrochemical detector is +500-+600mV. The detection limit for the tea catechins was about 0.2pmol (40pmol/ml) under the conditions used. When an extract from canned green tea was examined, gallic acid, gallocatechin and gallocatechin gallate were selectively detected in addition to the five catechins indicated above. Methylxanthins and vitamin C, which are often found in large amounts in green tea, did not interfere with determination of the tea catechins. These results indicated that the HPLC-electrochemical detector method is highly selective and appropriate for the determination of tea catechins in food.
In order to establish suitable production conditions of canned tea drinks, first of all, caffeine, catechins and L-ascorbic acid in commercial canned tea drinks were quantitatively determined as indicative substances of quality change by high performance liquid chromatography and colorimetric analysis. Secondly, canned green tea drink was prepared as a trial to examine the influence of pH of extraction media and of heat processing on the stability of caffeine, catechins and L-ascorbic acid. From the analysis of various kinds of commercial canned tea drinks including oolong tea, black tea and green tea, it was found that the concentrations of caffeine and catechins in commercial canned tea drinks were 1/2-2/3 of those in normal tea infusion. The drinks kept at lower pH had higher retention of catechins From the test production of canned green tea, it was found that, (1) catechins were less stable than caffeine in heat processing, (2) L-ascorbic acid was considerably stable in heal processing, (3) most catechins decreased by heat processing but (+)-catechin was remarkably increased, (4) the increase of (+)-catechin was possibly caused by isomerization of(-)-epicatechin, (5) the isomerization of(-)-epicatechin was remarkably depressed in slightly acidic extraction media containing citric acid. In conclusion, the most dominant factor affecting the stability of catechins in tea drinks was pH of extraction media.
緑茶より抽出精製したカテキン類の口臭抑制効果を判定するため,CH3SHに対する消臭力,及び唾液にカテキン類を添加し,L-Metと共にインキュベート後発生したCH3SHを定量し,そのCH3SH産生抑制効果を測定した.また,カテキン類を添加したチューインガムを試作し,そのCH3SH産生抑制効果を判定した結果,以下の結論を得た.(1) カテキン類は強いCH3SH消臭力を有し,この効果は,従来より口腔内消臭剤として汎用されているSCCの効果をかなり上回るものであった.(2) 緑茶に含まれる4種のカテキンについて消臭力の測定を行った結果,その効果は,EC<ECg<ECG<EGCgの順に優れており,構造と消臭効果との相関関係が示唆された.(3) 唾液にカテキン類を添加し,これを24時間インキュベートした結果,L-Metを基質としたCH3SHの発生はコントロールと比較して,著しく抑制された.また,この効果はSCCの効果よりも強かった.(4) カテキン類を添加したチューインガムを試作し,唾液のCH3SH発生量を指標として,その口臭抑制効果について評価を行った結果,カテキン0.01%添加ガム咀嚼後においても,CH3SH発生は顕著に抑制された.以上のことからカテキン類は,口臭原因物質として注目されているCH3SHに対し,優れた消臭作用とその産生を抑制する作用を持つものと推定された.また,カテキン類を添加したチューインガムは,口臭抑制の目的で効果的であると考えられた.
茶葉より抽出したカテキン遊離型画分〔(-)-エピカテキン, (-)-エピガロカテキン〕である粗カテキンA分画(CF-Aと略),エステル型画分〔(-)-エピカテキンガレート,(-)-エピガロカテキンガレート〕である粗カテキンB分画(CF-Bと略),それらの混合物であるCF-mix,および(-)-エピガロカテキンガレート(EGCg)のS. mutansに対する抗菌作用について試験し,グルコン酸クロルヘキシジンの抗菌作用と比較した.またう蝕予防剤としての利用を前提としたいくつかの試験を行ない,次の結果を得た. (1) 生育阻害最低濃度はCF-Aで400～100μg/ml,CF-Bで100～50μg/ml,CF-mixで200～100μg/ml, EGCgで100-50μg/ml,およびグルコン酸クロルヘキシジンで1.6μg/ml以下であった.(2) 殺菌効果の検定では初菌数3.3×107にCF-Bを(31)川村・竹尾:茶葉カテキンの抗菌作用4675.0×103, 1.0×104μg/mlずつの添加で5.5×105, 3.6×104, 1.0×102にそれぞれ減少し, グルコン酸クロルヘキシジンでは初菌数3.3×107に2.0×103μg/ml添加で3.0×10 3に減少した.(3) カテキンの抗菌作用におよぼす歯磨剤主要成分の影響はラウリル硫酸ナトリウムおよびD-ソルビトーでは影響はみられず,安息香酸ナトリウムは僅かに相乗作用がみられた.
1. Oxygen is a toxic gas - an introductionto oxygen toxicity and reactive species 2. The chemistry of free radicals and related 'reactive species' 3. Antioxidant defences Endogenous and Diet Derived 4. Cellular responses to oxidative stress: adaptation, damage, repair, senescence and death 5. Measurement of reactive species 6. Reactive species can pose special problems needing special solutions. Some examples. 7. Reactive species can be useful some more examples 8. Reactive species can be poisonous: their role in toxicology 9. Reactive species and disease: fact, fiction or filibuster? 10. Ageing, nutrition, disease, and therapy: A role for antioxidants?
Summary Flavonol glycosides were isolated from black tea by column chromatography with polyamide. A RP-HPLC method with gradient elution (solvent A: 2% acetic acid; solvent B: acetonitrile) was used for the separation of the flavonol glycosides. Identification was carried out by UV spectra using a diode-array detector. Among these compounds rutoside is of special interest because of its physiological activity. The amounts in black tea were 86 to 214 mg/100 g, if extracted with hot water only.
The effect of black and green tea on the NO system was tested. Beside a general effect i.e. NO scavenging, the teas interacted with good, i.e. relaxation of the aorta, and bad effects, i.e. peroxynitrite scavenging, of NO. Green tea was a better NO and peroxynitrite scavenger than black tea. Epigallocatechin gallate was the major identified contributor to both the peroxynitrite and NO scavenging. The theaflavins, only present in black tea, also had a substantial contribution to the NO scavenging of black tea. The teas were found to have only a minor and nonspecific effect on the NO mediated vasorelaxation. Based on these results it is concluded that tea discriminates between the good and bad effects of NO; tea is likely to prevent NO toxicity primarily.
The concentrations of the major tea flavanols in nine green teas from China and Japan have been investigated. Results show that epi-gallocatechin (EGC) is the most prevalent flavanol and not epi-gallocatechin gallate (EGCG) as previously thought. Studies of the equilibrium behaviour of extraction of tea flavanols and caffeine into aqueous media at 80°C and 60°C for one of the teas, Sen Cha Uji Tsuyu, indicate that extraction efficiencies are similar to that for extraction of soluble components from black teas. These studies also support the idea of EGC being the flavanol with the highest concentration. This is of relevance to the current interest in tea flavanols as antimutagenic agents in the treatment of cancers. From the flavanol content results there appears to be a correlation between the amount of flavanol and the price of the tea. It is possible that this might be used to aid the pricing of green teas at auction.
The effects of green tea polyphenols, inhibitors of various biological activities of cariogenic bacteria in vitro, on caries development were examined using conventional rats. A total of 96 male rats were divided into 8 groups and the rats in the test groups were given tea polyphenols ranging from 0.1% to 0.5% in their cariogenic diet or drinking water for 40 days. Total fissure caries lesions was significantly reduced by the addition of tea polyphenols to the diet or in the drinking water. Diet containing 0.1% tea polyphenols demonstrated about 40% reduction of total fissure caries lesions. No toxic effect of tea polyphenols on rats were observed under these experimental conditions.
The association of coffee and tea consumption to anemia was investigated among 11,684 19 to 74 year old NHANES II participants. Anemia was assessed among 5.3% of the subjects when 2 of the 4 haematologic parameters (TS, EP, MCV, Hb) were below the acceptable value. Two logistic regression models were tested to examine the relationship between the probability of anemia and coffee and tea consumption when controlling for other dietary variables and demographic factors. Model one examined the relationship between coffee and tea consumption when dietary variables (iron and ascorbic acid), and age and sex were included. Contrary to laboratory findings of positive association between tea and coffee intake and anemia, average daily consumption of 3.7 cups of tea and coffee was significantly (P<0.05) but negatively associated with anemic status. Dietary iron and ascorbate were also negatively associated but not significantly. Age and sex made a stronger contribution to explaining the likelihood of anemia than any of the dietary factors. When socioeconomic factors were added to the above model all dietary variables, including coffee and tea intake, remained negatively associated and made no significant contribution to the probability of being anaemic. Based on standardized coefficients, race, education, sex, age, and poverty made significant contributions to anaemic status of the participants in that order. Our analysis of NHANES II data suggests that demographic characteristics may be more important predictors of anaemic status than coffee and tea, iron or ascorbic acid intake of individuals when the latter two nutrients are not limiting in the diet.
A synthetic mixture of epigallocatechin gallate and gallocatechin gallate was separated using multiple countercurrent chromatographic instruments by connecting the separation columns in series. Peak resolution increased according to the formula Rs-n = nRs-1, where n is the number of columns connected; Rs-n and Rs-1, the peak resolution obtained from n columns and a single column, respectively. Various sample sizes and concentrations were applied to four columns connected in series. The results indicated that the sample loading capacity is increased 11 times that of the single instrument for the same peak resolution.
We present a theoretical analysis of electron and hole escape mechanisms from a quantum well (QW) in an external electric field. The influence of carriers and dopant ion charges on the band structure is simulated with a self-consistent Poisson-Schrödinger solver. A new escape mechanism called the phonon-assisted sequential tunneling is proposed as an alternative to direct tunneling and thermionic emission from the QW ground state. Our calculation shows that at high forward biases, POP phonon-assisted sequential tunneling and thermionic emission dominate the electron and hole escape times. At high reverse biases, direct electron tunneling from the QW ground state to the reservoir determines the turn-off time constant, while heavy holes take a longer time to escape than electrons.
Quercetin and kaempferol rhamnodiglucosides are characteristic compounds of Camellia sinensis. Their structures were determined as quercetin-and kaempferol-3-O-[β-D-glucopyranosyl-(1 → 3)-α-L-rhamnopyranosyl-(1 → 6)-β-D-glucopyranosides]. Reversed phase HPLC methods for preparative isolation and analytical separation of both compounds were developed. The structural elucidation of the compounds by means of NMR spectroscopy, fast atom bombardment MS and GC-MS of the sugar moieties is described. Black tea contains 0–0·95 g kg−1 quercetin rhamnodiglucoside and 0·05–1·25 g kg−1 kaempferol rhamnodiglucoside.
In the recent Scientific Correspondence1 by J. Jankun et al., entitled "Why drinking tea could prevent cancer", I was surprised to find that a review article by myself and Z.-Y. Wang about the effects of green and black tea on cancer2 had been misquoted. In addition, I find the hypothesis in this report as to why drinking tea could prevent cancer misleading, and believe that the data were erroneously interpreted with regard to the mechanisms of cancer inhibition by tea. I would like to clarify four points.
A screening method, which allows the simple and rapid determination of the flavanolic composition of plant and food extracts, has been developed. The method is based on a postcolumn chemical reaction with p-dimethylaminocinnamaldehyde with detection at 640 nm after HPLC separation and measurement of the UV absorbance at 280 nm in a diode array detector. This approach allows one not only to obtain the flavanol profiles of the samples but also to characterize the compounds present in the chromatograms through their A640/A280 absorbance ratio combined with the retention time and the UV spectrum. The advantages of this procedure are shown by applying it to the study of the flavanol composition of some beverages, including red wine, beer, apple cider, and sour cherry and blackthorn fruit liqueurs. Keywords: Flavan-3-ols; procyanidins; prodelphinidins; beverages; wine; beer; cider
The composition and content of flavonol glycosides (FGs) have been measured in infusions of a range of black tea and black tea products. Tea contains a mixture of glycosides of quercetin, kaempferol, and myricetin and the total level of these glycosides, in infusions prepared in a normal domestic manner, for the leaf teas varied from 36.5 to 88.3 mg/L, although greater variation was observed for the tea products, from 7.0 to 428.1 mg/L. Altogether seven quercetin, five kaempferol, and two myricetin glycosides were detected; their relative amounts varied significantly in the different samples. The significance of these differences in relation to the bioavailability and potential bioactivity of these compounds is discussed. Keywords: Tea; flavonol; glycoside; HPLC; quercetin; kaempferol; myricetin
At present, the commonly used HPLC method for the analysis of caffeine content in tea brews employs direct application of the samples on the column. This practice gradually reduces the efficiency of the column and shortens its life. In the modified method, the interfering tea pigments are effectively removed by passing the sample through a Sep-Pak C18 cartridge. Then its injection on a reversed phase μ-Bondapak C18 column employing acetonitrile and water (20:80 v/v) as mobile phase reduces the analysis time without affecting either the resolution of the peaks or the accuracy of caffeine determination. This method is shown to estimate accurately soluble caffeine contents in the brews of black tea, decaffeinated tea, and decaffeinated instant tea samples. Thus, the method is ideally suited for rapid routine anaylsis of black tea and its products. Keywords: Caffeine; Sep-Pak C18; decaffeinated tea; HPLC; instant tea
The relationship between antioxidant activity and antimutagenicity of various tea extracts (green tea, pouchong tea, oolong tea, and black tea) was investigated. All tea extracts exhibited markedly antioxidant activity and reducing power, especially oolong tea, which inhibited 73.6% peroxidation of linoleic acid. Tea extracts exhibited a 65-75% scavenging effect on superoxide at a dose of 1 mg and 30-50% scavenging effect on hydrogen peroxide at a dose of 400 mu g. They scavenged 100% hydroxyl radical at a dosage of 4 mg except the black tea. Tea extracts also showed 50-70% scavenging effect on alpha,alpha-diphenyl-beta-picrylhydrazyl radical. The antioxidant activity and the scavenging effects on active oxygen decreased in the order semifermented tea > nonfermented tea > fermented tea. Tea extracts showed strong antimutagenic action against five indirect mutagens, i.e., AFB(1), Trp-P-1, Glu-P-1, B[a]P, and IQ, especially oolong and pouchong teas. The antioxidant effect of tea extracts was well correlated to their antimutagenicity in some cases but varied with the mutagen and antioxidative properties.
Further applications of a spectrophotometric method are described for the determination of polyphenolic oxidation products in black tea liquors for the assessment of quality in tea. In addition to calculating theaflavin and thearubigin contents from optical density measurements at 380 mu, values for total colour and brightness have been calculated from optical density measurements at 460 mu. Confirmation has been obtained that theaflavin content is an extremely important factor in determining quality in black tea, and in determining ‘brightness’ in tea infusions. Thearubigins contribute to colour and strength. The effects of seasonal variations and of methods of manufacture on the composition of tea have been examined. Changes in composition during storage of tea under adverse conditions of temperature and moisture content have been related to losses of quality. The effects of the composition of the water used on the composition and colour of tea infusions are also indicated.
Studies were carried out on the in-vitro availability of iron to determine the effect of addition of tea, milk and ascorbic acid to a standard cereal meal in all possible combinations.
The availability of iron from the cereal meal was low (3.92%). Tea, when added to the meal, had a significant depressing effect on available iron (2.56%). Addition of 100 mg ascorbic acid or 200 g milk completely counteracted the inhibitory effect of tea, and addition of both ascorbic acid and milk brought about an even greater enhancement in the in-vitro availability of iron than when either was added alone. This investigation reveals that milk is as effective a factor as ascorbic acid in counteracting the depressing effect of tea on in-vitro iron availability.
The non-volatile, water-soluble constituents of black tea were studied by using reversed-phase HPLC with a photodiode-array detector, using a linear gradient developed for this purpose. The data generated by this detector from one injection of a black tea liquor allowed information on the nature and purity of the constituents to be obtained. The following constituents were identified by the spectral data and the retention times given by reference compounds: caffeine, theobromine, (−)-epicatechin gallate, (−)- epigallocatechin gallate, gallic acid, chlorogenic acid (5-O-caffeoylquinic acid), p-coumaroylquinic acid, quercetin 3-glucoside, quercetin 3-rhamnosylglucoside, kaempferol 3-rhamnosylglucoside, and theaflavin digallate. Other peaks were classified by spectral data, but without reference compounds conclusive assignments could not be made. Finally, a group of peaks could be classified as coloured phenolic pigments, and tentatively assigned as thearubigins.
A method has been developed which enables the easy and inexpensive preparation of gram quantities of (–)-epigallocatechin gallate from green tea (Camellia sinensis). A decaffeinated aqueous brew of commercial green tea is treated with caffeine (30 mm). The precipitate is redissolved after decaffeination with chloroform and further purified by solvent partition with ethyl hexanoate and propyl acetate. Commercial leaf (25 g) yields 400 mg (–)-epigallocatechin gallate at better than 80% purity, as judged by reversed phase HPLC.
Keywords:chemoprotection;antimutagenesis;green tea;antioxidant catechins
A component of aqueous extracts of green tea (Camellia sinensis), known to reverse methicillin-resistance in staphylococci, causes extensive morphological changes in methicillin-resistant but not in methicillin-sensitive Staphylococcus aureus. Clumps of partly divided cocci, consisting of up to 14 individuals, with thickened internal but normal external cell walls were seen by electron microscopy in cultures of methicillin-resistant S. aureus grown in the presence of the active principle. The morphological changes observed were consistent with selective inhibition of penicillin-binding proteins.
Free flavonol aglycones, potentially mutagenic, were determined in vegetable infusions, in fresh and pickled vegetables and in vegetables exposed to mold growth. None of the infusions tested contained any considerable amount of free mutagenic aglycones, but some vegetables, such as red onions and cucumbers, had appreciable amounts of free flavonol aglycones, especially in the external layers. The treatment used in the production of pickled vegetables did not change the quality and quantity of the flavonols but the presence of molds altered the quantity of flavonol aglycones and glycosides.
A simple high performance liquid chromatographic analysis for tea catechins, caffeine and gallic acid with an isocratic elution system was developed. The separation system consisted of a C18 reversed-phase column, an isocratic elution system of methanol/water/orthophosphoric acid, and an UV detector. This method is ideally suited for rapid, routine analysis for the determination of catechins in green tea with good repeatability and accuracy of results. Furthermore, this method can be applied to all kinds of tea and tea products, and is especially useful for the determination of (+)-catechin, which was regarded as being in too low a concentration to detect, and (−)-gallocatechin gallate, which was regarded as a measure for heat treatment for green tea.
The qualitatively important components of green tea (theanine, caffeine, ascorbic acid, (−)-epicatechin, (−)-epigallocatechin, (−)-epicatechin gallate and (−)-epigallocatechin gallate) were analyzed simultaneously by using capillary electrophoresis. The running buffer used was borate buffer (80 mM, pH 8.4) containing 50 mM of sodium dodecylsulfate. The extracts of green tea, oolong tea and black tea were analyzed using this method. Green teas of different plucking dates and the leaf samples from different positions in one shoot were also measured using this method. These results showed that this method will considerably save time and labor for the analysis of these components, and is quite useful for the quality estimation of teas (particularly of green tea) and characterization of fresh tea leaves.
A simple and fast high performance liquid chromatography analysis method for eight tea catechins and caffeine using an ODS column and a water-acetonitrile-phosphoric acid mobile phase system was developed. The catechins, epicatechin epigallocatechin, epicatechin gallate, epigallocatechin gallate, catechin, catechin gallate, gallocatechin and gallocatechin gallate, and caffeine were separated by an acetonitrile gradient within 20 min. The detection limit of this method was approximately 0.2 ng for all nine compounds and the quantitation curves were linear between 2 ng to 2 μg. Some Japanese green tea samples were analyzed using this method. No extraneous peaks interfered with the analysis and the detection limit of each compound was less than 0.02% of the dry weight of the tea.
A study of a variety of stationary phases and elution conditions for the liquid chromatographic (LC) determination of six biologically active green tea catechins has resulted in the development of two well-defined, reproducible systems for such analyses which overcome limitations of previously described methods. Comparison of six reversed-phase columns indicates that deactivated stationary phases, which utilize ultrapure silica and maximize coverage of the silica support, provide significantly improved separation and chromatographic efficiencies for catechin analyses using LC, compared to conventional monomeric or polymeric C18 columns. Evaluation of elution conditions used for the separations reveals that the presence of acid in the mobile phase (0.05% trifluoroacetic acid) is essential for both the complete resolution of the catechins present in tea and the efficient chromatography of these compounds. The efficacy of one of the developed systems was demonstrated by the quantitative measurement of the six biologically active catechins in aqueous infusions of green tea (Camellia sinensis). Overall precision values for the analyses were within the range 0.3–1% (relative standard deviation).