Application Of Green Tea Polyphenols Research Articles

Czynniki determinujące status oksydacyjno-antyoksydacyjny i jego odpowiedź na wysiłek fizyczny

Nasilenie przemian metabolicznych podczas wysiłku fizycznego sprzyja powstawaniu wolnych rodników i reaktywnych form tlenu, co może zaburzać równowagę oksydacyjno-antyoksydacyjną w kierunku stresu oksydacyjnego. Warunki te sprzyjają uszkodzeniu struktur komórkowych, przyczyniając się do zmęczenia i spadku zdolności wysiłkowych. W pracy omówiono wysiłkowe źródła wolnych rodników tlenowych oraz obronę antyoksydacyjną ustroju, jak też czynniki wpływające na nasilenie powysiłkowego stresu oksydacyjnego. W kolejnej części przedstawiono wyniki badań dotyczących efektywności podawania suplementów antyoksydacyjnych w warunkach wysiłkowych, głównie na przykładzie polifenoli zielonej herbaty. Zwrócono też uwagę na potencjalne zagrożenia związane z przyjmowaniem suplementów antyoksydacyjnych w nadmiernych ilościach. Wynika to z faktu, iż reaktywne formy tlenu odgrywają ważną rolę jako przekaźniki sygnałów komórkowych, umożliwiając uzyskanie adaptacji do wysiłku fizycznego i wzrost zdolności wysiłkowych w odpowiedzi na trening sportowy (siły, wytrzymałości). W dalszej części omówiono czynniki genetyczne warunkujące poziom enzymatycznej obrony antyoksydacyjnej i wrażliwość na stres oksydacyjny, główną uwagę skupiając na polimorfizmach genów kodujących enzymy antyoksydacyjne. Przedstawiono zależność pomiędzy polimorfizmem genu mitochondrialnej dysmutazy ponadtlenkowej (enzymu stanowiącego pierwszą linię obrony przed szkodliwym wpływem wolnych rodników tlenowych na organizm) a zmianami parametrów równowagi oksydacyjno-antyoksydacyjnej w odpowiedzi na trening sportowy. Na koniec podkreślono użyteczność oznaczeń wspomnianego powyżej polimorfizmu w selekcji sportowców podatnych na stres oksydacyjny, w celu indywidualizacji zaleceń żywieniowych dotyczących podaży antyoksydantów w diecie lub w postaci suplementów.

Transcriptomic analysis of the response of Pseudomonas fluorescens to epigallocatechin gallate by RNA-seq.

Epigallocatechin gallate (EGCG) is a main constituent of green tea polyphenols that are widely used as food preservatives and are considered to be safe for consumption. However, the underlying antimicrobial mechanism of EGCG and the bacterial response to EGCG are not clearly understood. In the present study, a genome-wide transcriptional analysis of a typical spoilage bacterium, Pseudomonas fluorescens that responded to EGCG was performed using RNA-seq technology. A total of 26,365,414 and 23,287,092 clean reads were generated from P. fluorescens treated with or without 1 mM EGCG and the clean reads were aligned to the reference genome. Differential expression analysis revealed 291 upregulated genes and 134 downregulated genes and the differentially expressed genes (DEGs) were verified using RT-qPCR. Most of the DGEs involved in iron uptake, antioxidation, DNA repair, efflux system, cell envelope and cell-surface component synthesis were significantly upregulated by EGCG treatment, while most genes associated with energy production were downregulated. These transcriptomic changes are likely to be adaptive responses of P. fluorescens to iron limitation and oxidative stress, as well as DNA and envelope damage caused by EGCG. The expression of specific genes encoding the extra-cytoplasmic function sigma factor (PvdS, RpoE and AlgU) and the two-component sensor histidine kinase (BaeS and RpfG) were markedly changed by EGCG treatment, which may play important roles in regulating the stress responses of P. fluorescens to EGCG. The present data provides important insights into the molecular action of EGCG and the possible cross-resistance mediated by EGCG on P. fluorescens, which may ultimately contribute to the optimal application of green tea polyphenols in food preservation.

Potential natural antioxidants: adjuvant effect of green tea polyphenols in periodontal infections.

Polyphenols constitute the major component in green tea, which represent a cluster known as catechins. The presence of polyphenols, especially the amino acid theanine and catechins with its antioxidant properties in green tea make them ideal for medicinal- dental applications. The objective of the paper is to delineate the role of green tea polyphenols in periodontal disease. The Pub med data base was searched for human clinical studies, reviews pertinent to application of green tea polyphenols in periodontal health dating from Sep 1980- Sep 2014. The retrieved inference from the epidemiological surveys, in vitro studies and overviews of polyphenols, postulate green tea as potential natural antioxidant. Green tea mouthwashes possess limitations, which make them ineffective during the chronic stages of periodontitis. Human studies reveal that the prognosis of periodontal disease is better when the green tea catechins are used via local drug delivery. The maintenance of periodontal health could be enhanced by emphasizing the habit of drinking green tea in periodontitis patients. The future scope of the research demands the analysis of polyphenols at molecular level to have a better understanding of its overwhelming applications.

Increasing the antioxidant activity of green tea polyphenols in the presence of iron for the reduction of graphene oxide

An easy method for green and low-temperature (40°C) reduction of graphene oxide (GO) by increasing the antioxidant activity of green tea polyphenols (GTPs) in the presence of iron was developed. The reduction level (obtained by X-ray photoelectron spectroscopy) and electrical conductivity (obtained by current–voltage measurement) of the GO sheets reduced by GTPs in the presence of iron were comparable to those of hydrazine-reduced GO and much better than those of the GO reduced by only GTPs (in the absence of iron) at reduction temperatures of 40–80°C. Raman spectroscopy indicated that application of GTPs in the presence of iron, in contrast to hydrazine, resulted in better recovering of the sp2-hybridized structure of the sheets. The lasting water dispersion of the polyphenolic-reduced GO sheets in the presence of iron was assigned to π–π adsorption of Fe2+-polyphenol radicals on surface of the reduced sheets. A mechanism describing the role of iron in the reduction of the GO by epicatechin gallate and epigallocatechin gallate of green tea was also proposed.

Green Tea and Skin—Anticarcinogenic Effects

Because of its special aroma, green tea is a popular beverage consumed by some human populations worldwide. In recent years, many laboratory studies have shown that in a variety of animal tumor bioassay systems the administration of green tea, specifically the polyphenolic fraction isolated from green tea leaves (green tea polyphenols), affords protection against cancer induction. In mouse skin tumor bioassay systems, topical application of green tea polyphenols to skin has been shown to result in protection against a) 3-methylcholanthrene-induced skin tumorigenicity, b) 7,12-dimethylbenz(a)anthracene (DMBA)-induced skin tumor initiation, c) 12-O-tetradecanoylphorbol-13-acetate and other tumor promoters caused tumor promotion in DMBA-initiated skin, and d) benzoyl peroxide- and 4-nitroquinoline N-oxide caused enhanced malignant progression of nonmalignant lesions. Green tea extract has also been shown to cause partial regression of established skin papillomas in mouse. Similarly, chronic oral feeding of green tea polyphenols or water extract of green tea has also been shown to result in the protection against both chemical carcinogen- and ultraviolet B radiation-induced skin tumorigenicity. Collectively these data suggest that green tea possesses significant chemopreventive effect against each stage of carcinogenesis, and that it may be useful against inflammatory responses associated with the exposure of skin to chemical tumor promoters as well as to solar radiation. Available data regarding the mechanism by which green tea affords these diversified effects is discussed.