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Special Issue "Tea Chemistry"

A special issue of Molecules (ISSN 1420-3049). This special issue belongs to the section "Natural Products Chemistry".

Deadline for manuscript submissions: closed (31 December 2018)

Special Issue Editor

Guest Editor
Prof. Dr. Declan P. Naughton

School of Life Science, Pharmacy and Chemistry, FACULTY OF SCIENCE, ENGINEERING & COMPUTING, Kingston University London, Penrhyn Rd, Kingston upon Thames, Surrey KT1 2EE, UK
Website | E-Mail
Interests: inflammation; infection; oxidative stress; nutrition; toxicology; food safety; functional foods; natural products; anti-microbial and anti-inflammatory agents and mechanisms; bioinorganic chemistry; drug delivery

Special Issue Information

Dear Colleagues,

Tea is the most widely-consumed beverage in the world after water. Annually, it is a multi-billion dollar import business in the US, where less than 100 acres are currently farmed. Although Camellia sinensis (C.s.) growth and tea production and consumption are major economic drivers worldwide, surprisingly little is known about the environmental factors that contribute to sustainable cultivation of high quality tea even in regions where tea has grown for centuries. Many agree that water, soil, and climate affect tea plant sustainability, impact nutrient uptake and impact tea quality. However, the chemical basis of these correlates is yet to be established.

This Special Issue aims to attract contributions on all aspects of the chemistry and chemical biology of Camellia sinensis growth that impact tea quality. Contributions focused on correlating chemical measurements of growing conditions with tea quality are of special interest.

Manuscript Submission Information

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Keywords

•    chemistry of tea derived
•    chemical biology
•    chemical measurements of growing conditions
•    tea extraction
•    tea bioactivities
•    tea and health
•    metabolomics
•    Chemistry profile/sensory attributes of prepared tea

Published Papers (6 papers)

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Research

Open AccessArticle Active Components, Antioxidant, Inhibition on Metabolic Syndrome Related Enzymes, and Monthly Variations in Mature Leaf Hawk Tea
Molecules 2019, 24(4), 657; https://doi.org/10.3390/molecules24040657
Received: 1 January 2019 / Revised: 28 January 2019 / Accepted: 9 February 2019 / Published: 13 February 2019
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Abstract
Hawk tea is a rich and edible resource, traditionally used as a beverage in South China. This drink has many pharmacologic effects, such as acting as an antioxidant and reducing blood sugar and lipids. The objective of this work was to explore the [...] Read more.
Hawk tea is a rich and edible resource, traditionally used as a beverage in South China. This drink has many pharmacologic effects, such as acting as an antioxidant and reducing blood sugar and lipids. The objective of this work was to explore the active compound contents, bioactivities and their monthly changes, and optimize the harvest time. In the present study, Hawk tea from each month in 2017 was collected and extracted with 70% (v/v) ethanol. The contents of the total flavonoids and total phenols were determined using the colorimetric method. We determined the contents of seven characteristic active substances—hyperin, isoquercitrin, trifolin, quercitrin, astragalin, quercetin, and kaempferol—using high-performance liquid chromatography. The crude extract was tested for its antioxidant and inhibitory properties on enzymes involved in metabolic syndrome. Specifically, 2,2-diphenyl-1-picrylhydrazyl, 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid), ferric-reducing power assay, and the inhibition capacity test on α-glucosidase and lipase were conducted to determine the antioxidant effect in vitro, as well as the reduction of blood sugar and lipids. Monthly variations in activities and components were determined by numeric analysis and comparison. Correlation analysis revealed that antioxidant effects are significantly correlated with the total flavonoids. The hierarchical cluster analysis of bioactivities and their contents indicates that October and November are the best harvesting months, which differs with the habitual collection of Hawk tea. Full article
(This article belongs to the Special Issue Tea Chemistry)
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Open AccessArticle Identification of a Novel Gene Encoding the Specialized Alanine Decarboxylase in Tea (Camellia sinensis) Plants
Molecules 2019, 24(3), 540; https://doi.org/10.3390/molecules24030540
Received: 21 December 2018 / Revised: 18 January 2019 / Accepted: 27 January 2019 / Published: 1 February 2019
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Abstract
Theanine, a unique amino acid in Camellia sinensis, accounts for more than 50% of total free amino acids in tea and has a significant contribution to the quality of green tea. Previous research indicated that theanine is synthesized from glutamic acid (Glu) [...] Read more.
Theanine, a unique amino acid in Camellia sinensis, accounts for more than 50% of total free amino acids in tea and has a significant contribution to the quality of green tea. Previous research indicated that theanine is synthesized from glutamic acid (Glu) and ethylamine mainly in roots, and that theanine accumulation depends on the availability of ethylamine which is derived from alanine (Ala) decarboxylation catalyzed by alanine decarboxylase (AlaDC). However, the specific gene encoding AlaDC protein remains to be discovered in tea plants or in other species. To explore the gene of AlaDC in tea plants, the differences in theanine contents and gene expressions between pretreatment and posttreatment of long-time nitrogen starvation were analyzed in young roots of two tea cultivars. A novel gene annotated as serine decarboxylase (SDC) was noted for its expression levels, which showed high consistency with theanine content, and the expression was remarkably high in young roots under sufficient nitrogen condition. To verify its function, full-length complementary DNA (cDNA) of this candidate gene was cloned from young roots of tea seedlings, and the target protein was expressed and purified from Escherichia coli (E. coli). The enzymatic activity of the protein for Ala and Ser was measured in vitro using ultra-performance liquid chromatography coupled with mass spectrometry (UPLC-MS). The results illustrated that the target protein could catalyze the decarboxylation of Ala despite of its high similarity with SDC from other species. Therefore, this novel gene was identified as AlaDC and named CsAlaDC. Furthermore, the gene expression levels of CsAlaDC in different tissues of tea plants were also quantified with quantitative real-time PCR (qRT-PCR). The results suggest that transcription levels of CsAlaDC in root tissues are significantly higher than those in leaf tissues. That may explain why theanine biosynthesis preferentially occurs in the roots of tea plants. The expression of the gene was upregulated when nitrogen was present, suggesting that theanine biosynthesis is regulated by nitrogen supply and closely related to nitrogen metabolism for C. sinensis. The results of this study are significant supplements to the theanine biosynthetic pathway and provide evidence for the differential accumulation of theanine between C. sinensis and other species. Full article
(This article belongs to the Special Issue Tea Chemistry)
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Open AccessCommunication Characteristics of Free Amino Acids (the Quality Chemical Components of Tea) under Spatial Heterogeneity of Different Nitrogen Forms in Tea (Camellia sinensis) Plants
Molecules 2019, 24(3), 415; https://doi.org/10.3390/molecules24030415
Received: 28 December 2018 / Revised: 16 January 2019 / Accepted: 23 January 2019 / Published: 24 January 2019
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Abstract
Nitrogen (N) forms are closely related to tea quality, however, little is known about the characteristics of quality chemical components in tea under the spatial heterogeneity of different N forms. In this study, a split-root system, high performance liquid chromatography (HPLC), and root [...] Read more.
Nitrogen (N) forms are closely related to tea quality, however, little is known about the characteristics of quality chemical components in tea under the spatial heterogeneity of different N forms. In this study, a split-root system, high performance liquid chromatography (HPLC), and root analysis system (WinRHIZO) were used to investigate free amino acids (FAAs) and root length of tea plants under the spatial heterogeneity of different N forms. Uniform. (U.) ammonium (NH4+) (both compartments had NH4+), U. nitrate (NO3) (both compartments had NO3), Split. (Sp.) NH4+ (one of the compartments had NH4+), and Sp. NO3 (the other compartment had NO3) were performed. The ranking of total FAAs in leaves were as follows: U. NH4+ > Sp. NH4+/Sp. NO3 > U. NO3. The FAA characteristics of Sp. NH4+/Sp. NO3 were more similar to those of U. NO3. The contents of the important FAAs (aspartic acid, glutamic acid, and theanine) that determine the quality of tea, increased significantly in U. NH4+. The total root length in U. NH4+ was higher than that in the other treatments. More serious root browning was found in U. NO3. In conclusion, NH4+ improved the accumulations of FAAs in tea leaves, which might be attributed to the root development. Full article
(This article belongs to the Special Issue Tea Chemistry)
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Open AccessArticle Phytochemical Composition and Antioxidant Activities of Two Different Color Chrysanthemum Flower Teas
Molecules 2019, 24(2), 329; https://doi.org/10.3390/molecules24020329
Received: 26 December 2018 / Revised: 10 January 2019 / Accepted: 16 January 2019 / Published: 17 January 2019
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Abstract
Chrysanthemum morifolium Ramat is a perennial flowering plant widely cultivated for use in a tea infusion and as a popular beverage. To identify and evaluate the tea infusion made with a γ-irradiated mutant chrysanthemum cultivar with dark purple petals (cv. ARTI-Dark Chocolate), its [...] Read more.
Chrysanthemum morifolium Ramat is a perennial flowering plant widely cultivated for use in a tea infusion and as a popular beverage. To identify and evaluate the tea infusion made with a γ-irradiated mutant chrysanthemum cultivar with dark purple petals (cv. ARTI-Dark Chocolate), its phytochemical composition and antioxidant activity were tested and compared with those of the commercially available chrysanthemum cultivar with yellow petals (cv. Gamguk) by HPLC-DAD-ESIMS, as well as DPPH and ABTS radical scavenging assays. The purple chrysanthemum tea contained anthocyanins and linarin, which were not detected in the yellow chrysanthemum tea and the content of chlorogenic acid, acacetin-7-O-β-glucoside, and luteolin was higher compared with the yellow chrysanthemum tea. In contrast, the yellow chrysanthemum tea had higher luteolin-7-O-β-glucoside, 3,5-dicaffeoylquinic acid, apigenin-7-O-β-glucoside, and apigenin contents in comparison with the purple chrysanthemum tea. In addition, the content and antioxidant activity of the two chrysanthemum teas were investigated according to different water temperatures and infusing time. The yellow chrysanthemum tea did not show any significant differences according to infusing time and temperature, while the purple chrysanthemum tea was more influenced by the infusing time than water temperature, showing the highest total compound content in the infusing condition of 100 °C and 4 min. Moreover, the floral scent volatiles of the two chrysanthemum tea sources were analyzed using HS-SPME-GC-MS. In the DPPH radical scavenging assay, the purple chrysanthemum tea broadly showed greater antioxidant activity than did the yellow chrysanthemum tea, corresponding to the high content of anthocyanins known as the powerful antioxidant. Further, both chrysanthemum flower teas exhibited strong ABTS radical scavenging effects ranging from 76% to 61% under all infusing conditions. Therefore, the purple chrysanthemum cultivar, ARTI-Dark Chocolate, is worthy of breeding as a new tea cultivar. Full article
(This article belongs to the Special Issue Tea Chemistry)
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Open AccessArticle Involvement of the Hydroperoxy Group in the Irreversible Inhibition of Leukocyte-Type 12-Lipoxygenase by Monoterpene Glycosides Contained in the Qing Shan Lu Shui Tea
Molecules 2019, 24(2), 304; https://doi.org/10.3390/molecules24020304
Received: 26 December 2018 / Revised: 8 January 2019 / Accepted: 14 January 2019 / Published: 15 January 2019
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Abstract
We have previously found two novel monoterpene glycosides, liguroside A and liguroside B, with an inhibitory effect on the catalytic activity of the enzyme leukocyte-type 12-lipoxygenase in the Qing Shan Lu Shui tea. Here, two new monoterpene glycosides, liguroside C and liguroside D [...] Read more.
We have previously found two novel monoterpene glycosides, liguroside A and liguroside B, with an inhibitory effect on the catalytic activity of the enzyme leukocyte-type 12-lipoxygenase in the Qing Shan Lu Shui tea. Here, two new monoterpene glycosides, liguroside C and liguroside D which inhibit this enzyme, were isolated from the same tea. The spectral and chemical evidence characterized the structures of these compounds as (5E)-7-hydroperoxy-3,7-dimethyl-1,5-octadienyl-3-O-(α-l-rhamnopyranosyl)-(1′′→3′)-(4′′′-O-trans-p-coumaroyl)-β-d-glucopyranoside and (2E)-6-hydroxy-3,7-dimethyl-2,7-octadienyl-3-O-(α-l-rhamnopyranosyl)-(1′′→3′)-(4′′′-O-trans-p-coumaroyl)-β-d-glucopyranoside, respectively. These ligurosides, which irreversibly inhibited leukocyte-type 12-lipoxygenase, have a hydroperoxy group in the monoterpene moiety. Additionally, monoterpene glycosides had the same backbone structure but did not have a hydroperoxy group, such as kudingoside A and lipedoside B-III, contained in the tea did not inhibit the enzyme. When a hydroperoxy group in liguroside A was reduced by using triphenylphosphine, the resultant compound, kudingoside B, showed a lower inhibitory effect on the enzyme. These results strongly suggest the involvement of the hydroperoxy group in the irreversible inhibition of the catalytic activity of leukocyte-type 12-lipoxygenase by the monoterpene glycosides contained in the Qing Shan Lu Shui tea. Full article
(This article belongs to the Special Issue Tea Chemistry)
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Open AccessArticle Bioactive Compound Fingerprint Analysis of Aged Raw Pu’er Tea and Young Ripened Pu’er Tea
Molecules 2018, 23(8), 1931; https://doi.org/10.3390/molecules23081931
Received: 16 July 2018 / Revised: 26 July 2018 / Accepted: 2 August 2018 / Published: 2 August 2018
Cited by 1 | PDF Full-text (1241 KB) | HTML Full-text | XML Full-text
Abstract
Pu’er tea produced from Camellia sinensis var. assamica is a widely appreciated and consumed beverage that can be divided into two kinds of tea depending on the different fermentation processed used, the special sensory characteristics, and their chemical composition. However, authentication seems to [...] Read more.
Pu’er tea produced from Camellia sinensis var. assamica is a widely appreciated and consumed beverage that can be divided into two kinds of tea depending on the different fermentation processed used, the special sensory characteristics, and their chemical composition. However, authentication seems to be very important for such teas, as they are traded to comparatively high prices, especially in Europe. The results for selected biochemical markers showed that aged raw pu’er tea contained 210.2 mg GAE/g polyphenols, of which 2.2 mg/g were gallic acid, 16.1 mg/g theogallin, 35.1 mg/g (−)-epigallocatechin gallate, and 40.1 mg/g (−)-epicatechin gallate, on average. Young ripened pu’er tea contained about 104.6 mg GAE/g polyphenols, of which 5.5 mg/g gallic acid, 0.9 mg/g theogallin, 0.7 mg/g (−)-epigallocatechin gallate, and 1.8 mg/g (−)-epicatechin gallate, on average. An additional objective of the present study was to unravel the best brewing conditions for optimal extraction of the bioactive compounds. Infusions of nineteen commercial teas (from pu’er cakes) were obtained at different time-temperature ratios for studying the content of bioactive compounds (flavan-3-ols, flavonols, caffeoylquinic acids, methylxanthines). Brewing at 90 °C for 5 min was the best condition to obtain a high content of total polyphenols in ripened pu’er tea. Principal component analysis and hierarchical cluster analysis showed, that young ripened and aged raw pu’er tea can be successfully differentiated by the analyzed chemical compounds. Principal component analysis results indicated that young ripened pu’er tea has higher contents of gallic acid, quercetin, and kaempferol than aged raw pu’er tea. Full article
(This article belongs to the Special Issue Tea Chemistry)
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