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Special Issue "Polyphenols and Antioxidants–The Chemistry of Tea"

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

Deadline for manuscript submissions: closed (30 May 2017)

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,

The chemistry and health benefits of tea—one of the most consumed beverages in the world—continue to receive a great deal of attention with, typically, over three thousand publications a year on the subject.

A major proportion of the publications are based in medical research, covering all of the major diseases, from a (bio)chemical, mechanistic and toxicological perspectives, through to improving the well-being of patients.

In vitro and in vivo experiments demonstrate the wide activities of tea and its components, including anti-microbial, anti-oxidant, anti-inflammatory, anti-hyperglycemic, anti-cariogenic, and wound healing. Teas have also been useful in a variety of combination therapies to reverse antimicrobial resistance and as cancer chemopreventive agents. Clinical trials have been reported for intact teas or tea components in a growing number of conditions.

Prof. Dr. Declan P. Naughton
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Molecules is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1800 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • cancer
  • inflammation
  • anti-oxidant
  • extraction
  • antimicrobial
  • wound healing

Published Papers (3 papers)

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Research

Open AccessArticle Black Tea High-Molecular-Weight Polyphenol-Rich Fraction Promotes Hypertrophy during Functional Overload in Mice
Molecules 2017, 22(4), 548; doi:10.3390/molecules22040548
Received: 16 February 2017 / Revised: 22 March 2017 / Accepted: 27 March 2017 / Published: 29 March 2017
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Abstract
Mitochondria activation factor (MAF) is a high-molecular-weight polyphenol extracted from black tea that stimulates training-induced 5′ adenosine monophosphate-activated protein kinase (AMPK) activation and improves endurance capacity. Originally, MAF was purified from black tea using butanol and acetone, making it unsuitable for food preparation.
[...] Read more.
Mitochondria activation factor (MAF) is a high-molecular-weight polyphenol extracted from black tea that stimulates training-induced 5′ adenosine monophosphate-activated protein kinase (AMPK) activation and improves endurance capacity. Originally, MAF was purified from black tea using butanol and acetone, making it unsuitable for food preparation. Hence, we extracted a MAF-rich sample “E80” from black tea, using ethanol and water only. Here, we examined the effects of E80 on resistance training. Eight-week old C57BL/6 mice were fed with a normal diet or a diet containing 0.5% E80 for 4, 7 and 14 days under conditions of functional overload. It was found that E80 administration promoted overload-induced hypertrophy and induced phosphorylation of the Akt/mammalian target of rapamycin (mTOR) pathway proteins, such as Akt, P70 ribosomal protein S6 kinase (p70S6K), and S6 in the plantaris muscle. Therefore, functional overload and E80 administration accelerated mTOR signaling and increased protein synthesis in the muscle, thereby inducing hypertrophy. Full article
(This article belongs to the Special Issue Polyphenols and Antioxidants–The Chemistry of Tea)
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Open AccessArticle Camellia sinensis L. Extract and Its Potential Beneficial Effects in Antioxidant, Anti-Inflammatory, Anti-Hepatotoxic, and Anti-Tyrosinase Activities
Molecules 2017, 22(3), 401; doi:10.3390/molecules22030401
Received: 17 January 2017 / Revised: 27 February 2017 / Accepted: 2 March 2017 / Published: 4 March 2017
Cited by 2 | PDF Full-text (2712 KB) | HTML Full-text | XML Full-text
Abstract
The aims of this study were to investigate the potential benefits of antioxidant, anti-inflammatory, anti-hepatotoxic, and anti-tyrosinase activities of a methanolic extract of fresh tea leaves (FTE) (Camellia sinensis L.). The antioxidant capacity was investigated using three different methods at different temperatures.
[...] Read more.
The aims of this study were to investigate the potential benefits of antioxidant, anti-inflammatory, anti-hepatotoxic, and anti-tyrosinase activities of a methanolic extract of fresh tea leaves (FTE) (Camellia sinensis L.). The antioxidant capacity was investigated using three different methods at different temperatures. The anti-inflammatory activity was studied in vitro by the inhibition of 5-lipoxygenase assay. The anti-hepatotoxic effect was investigated in CCl4-induced liver injury in rats. The anti-tyrosinase activities of the FTE and its principal phenolic compounds were investigated in l-3,4-dihydroxyphenylalanine (l-DOPA) oxidation by a mushroom tyrosinase. A molecular docking study was conducted to determine how the FTE’s principal catechins interact with the tyrosinase. The FTE exhibited the best shelf life at low temperatures and demonstrated concentration-dependent antioxidant, anti-inflammatory, anti-hepatotoxic, and anti-tyrosinase effects compared to positive references. Treatment of rats with the FTE at 2000 mg/kg/day for 28 consecutive days reversed CCl4-induced oxidative damage in hepatic tissues by lowering the levels of alanine aminotransferase by 69% and malondialdehyde by 90%. Our findings suggest that the FTE has the capacity to scavenge free radicals and can protect against oxidative stress induced by CCl4 intoxication. The docking results were consistent with our in vitro data, indicating the anti-tyrosinase potency of the principal catechins. Full article
(This article belongs to the Special Issue Polyphenols and Antioxidants–The Chemistry of Tea)
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Figure 1

Open AccessArticle Ultraviolet B (UVB) Photosensitivities of Tea Catechins and the Relevant Chemical Conversions
Molecules 2016, 21(10), 1345; doi:10.3390/molecules21101345
Received: 13 August 2016 / Revised: 22 September 2016 / Accepted: 6 October 2016 / Published: 10 October 2016
PDF Full-text (5848 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Ultraviolet B (UVB) photosensitivities of eight catechins were screened. In both water and ethanol, epicatechin (EC, 575 μM) and catechin (C, 575 μM) exhibited low photostabilities under 6 h UVB radiation with the generation of yellow photoproducts, while other catechins (epigallocatechin gallate, epigallocatechin,
[...] Read more.
Ultraviolet B (UVB) photosensitivities of eight catechins were screened. In both water and ethanol, epicatechin (EC, 575 μM) and catechin (C, 575 μM) exhibited low photostabilities under 6 h UVB radiation with the generation of yellow photoproducts, while other catechins (epigallocatechin gallate, epigallocatechin, epicatechin gallate, gallocatechingallate, gallocatechin, catechin gallate) were relatively UVB-insensitive. Photoisomerization and photolysis were two important UVB-induced reactions to EC whereas photolysis was the dominant reaction for C. The influencing factors of time (2–10 h), solvent (water, ethanol) and substrate concentration (71.875–1150 μM) on UVB-induced chemical conversions of EC and C were investigated, and eight photoproducts were identified through ultra performance liquid chromatography-diode array detection-tandem mass spectrometry (UPLC-DAD-MS/MS) and 1H nuclear magnetic resonance (1H-NMR analysis). Photolysis reaction involved two pathways, including radical reaction and photo-induced electron transfer reaction. The 2,2-diphenylpicrylhydrazyl (DPPH) scavenging abilities of eight catechins did not change upon 6 h UVB irradiation. EC and C are photosensitive catechins among eight catechins causing deep color. Full article
(This article belongs to the Special Issue Polyphenols and Antioxidants–The Chemistry of Tea)
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