Nature of Polyphenol−Protein Interactions

Siebert, Karl J.; Troukhanova, Nataliia V.; Lynn, P. Y.

doi:10.1021/jf9502459

Cited by 642 publications

(492 citation statements)

References 16 publications

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“…Addition of milk to tea leads to binding of tea components to milk protein (Siebert et al, 1996) and may thus prevent their uptake by the intestine. In contrast to a previous report (Sera®ni et al, 1996) a standard addition of 10 ± 15 % of milk did not in¯uence plasma antioxidant activity in the present study.…”

Section: Discussionmentioning

confidence: 99%

A single dose of tea with or without milk increases plasma antioxidant activity in humans

et al. 2000

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Objective: To investigate the effect of black and green tea consumption, with and without milk, on the plasma antioxidant activity in humans. Design: In a complete cross-over design, 21 healthy volunteers (10 male, 11 female) received a single dose of black tea, green tea (2 g tea solids in 300 ml water) or water with or without milk. Blood samples were obtained at baseline and at several time points up to 2 h post-tea drinking. Plasma was analysed for total catechins and antioxidant activity, using the ferric reducing ability of plasma (FRAP) assay. Results: Consumption of black tea resulted in a signi®cant increase in plasma antioxidant activity reaching maximal levels at about 60 min. A larger increase was observed after consumption of green tea. As anticipated from the higher catechin concentration in green tea, the rise in plasma total catechins was signi®cantly higher after consumption of green tea when compared to black tea. Addition of milk to black or green tea did not affect the observed increases in plasma antioxidant activity. Conclusions: Consumption of a single dose of black or green tea induces a signi®cant rise in plasma antioxidant activity in vivo. Addition of milk to tea does not abolish this increase. Whether the observed increases in plasma antioxidant activity after a single dose of tea prevent in vivo oxidative damage remains to be established.

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Section: Discussionmentioning

confidence: 99%

A single dose of tea with or without milk increases plasma antioxidant activity in humans

et al. 2000

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“…The discrepancy may be due to the difference of the α-amylase source or the test conditions. The essence of enzyme inhibition herein was protein precipitation through forming various complexes with polyphenols (Siebert et al 1996) or calcium (required as a cofactor for amylase enzyme activity) binding (Yoon et al 1983). EGCG had more galloylated groups and higher molecular weight, which may account for its better inhibiting activity.…”

Section: Lc-ms Analysis Of Qef8mentioning

confidence: 99%

In vitro antioxidant and pancreatic α-amylase inhibitory activity of isolated fractions from water extract of Qingzhuan tea

Cheng

Cai

et al. 2013

J Food Sci Technol

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In the present work, Qingzhuan tea, a unique dark tea produced by post-fermentation technology, was selected to investigate its antioxidant and pancreatic α-amylase inhibiting activities. Water extract of Qingzhuan tea was successively isolated by solvent partitioning procedures to obtain chloroform, ethyl acetate, n-butanol, sediment and residual aqua fractions. Of different fractions, the ethyl acetate fraction (QEF) had the highest total polyphenols and catechins contents, demonstrated the strongest DPPH radical scavenging activity and exhibited the greatest inhibitory effect on porcine pancreatic α-amylase activity in vitro. Further separation of QEF by a Sephadex LH-20 column generated eight subfractions (QEF1-QEF8), with QEF8 being the most active subfraction based on the assays above mentioned. The major active components in QEF8 were identified as catechins EGCG and ECG by LC-MS analysis, with contents of 22.29 % and 11.11 % respectively. Inhibitory effects of catechin standards EGCG and ECG on porcine pancreatic α-amylase activity were also observed. In conclusion, Qingzhuan tea or its water extract could be potentially used as complementary therapy ingredients for diabetes treatment through lowering postprandial blood glucose, and catechins EGCG and ECG may be the most efficient components in the water extract.

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“…Os aminoácidos, juntamente com os polissacarídeos, as dextranas, os fenóis e os polifenóis podem participar do processo de formação de precipitados, em bebidas fermentadas e destiladas, denominados flocos [4,14,16,18,19,20]. Embora os flocos não sejam prejudiciais à saúde e nem interfiram no aroma e sabor das bebidas, eles as depreciam no seu aspecto visual.…”

Section: -Introduçãounclassified

Compostos nitrogenados em bebidas destiladas: cachaça e tiquira

Polastro¹,

Boso²,

Andrade-Sobrinho³

et al. 2001

Ciênc. Tecnol. Aliment.

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. * A quem a correspondência deve ser enviada. RESUMOUtilizando métodos colorimétricos foram investigadas as presenças de íon amônio, uréia e aminoácidos em 51 amostras de aguardente de cana-de-açúcar (cachaça) e em 9 amostras de aguardente de mandioca (tiquira). Foram semelhantes os teores médios de íon amônio determinados para as aguardentes-de-cana (0,013mmoles/L) e de mandioca (0,010mmoles/L). As tiquiras apresentaram teores médios de aminoácidos (0,290mmoles/L) e uréia (1,45mmoles/L) superiores aos da aguardente-de-cana: 0,093mmoles/L e 0,316mmoles/L, respectivamente.Palavras-chave: íon amônio; uréia; aminoácidos; cachaça; tiquira. SUMMARYNITROGEN COMPOUNDS IN DISTILLED BEVERAGES: SU-GAR CANE AND CASSAVA SPIRITS. Ammonium ion, urea and amino acids were quantified by using colorimetric methods in 51 samples of sugar cane spirit (cachaça) and 9 samples of cassava spirit (tiquira). The average contents of ammonium ion for sugar cane (0.013mmoles/L) and cassava (0.010mmoles/ L) spirits are similar. Tiquiras present average contents of amino acids (0.290mmoles/L) and urea (1.45mmoles/L) higher than in sugar cane, which are 0.093mmoles/L and 0.316mmoles/L, respectively.Keywords: ammonium ion; urea; amino acids; cachaça; tiquira. -INTRODUÇÃOA etapa de multiplicação celular das leveduras responsáveis pela fermentação alcoólica no caldo de cana depende da presença de compostos nitrogenados tais como proteínas e ácidos nucléicos, os quais são fundamentais à biossíntese da estrutura celular [2]. O conteúdo inicial de nitrogênio total do mosto e as concentrações relativas de cada um dos constituintes nitrogenados afetam o crescimento das leveduras, a velocidade de fermentação e a formação do produto final [3,8]. A concentração de nitrogênio total em mostos é muito variável e dependente da espécie vegetal que se utiliza para a fermentação, da região produtora e das condições do solo [9]. O íon amônio (NH 4 + ) e os aminoácidos glutamina, ácido glutâmico, ácido aspártico, arginina, asparagina, serina e alanina são excelentes fontes de nitrogênio para a Saccharomyces cerevisiae [6]. Para manter a fermentação alcoólica do caldo de cana em boas condições e assegurar que a taxa de multiplicação celular permaneça elevada, a concentração ideal de nitrogênio amoniacal, geralmente adicionada na forma de (NH 4 ) 2 SO 4 , gira em torno de 10 a 35mmoles/L [2].A uréia é uma fonte de nitrogênio para as leveduras, no passado era freqüentemente adicionada à dorna de fermentação [2], porém atualmente sabe-se que não é aconselhável, pois este composto pode reagir com o etanol produzindo carbamato de etila, o qual é considerado carcinogênico [12,21]. Mesmo quando não adicionada, a uréia pode ser produzida durante o processo fermentativo, devido ao metabolismo das leveduras [21].Os aminoácidos, juntamente com os polissacarídeos, as dextranas, os fenóis e os polifenóis podem participar do processo de formação de precipitados, em bebidas fermentadas e destiladas, denominados flocos [4,14,16,18,19,20]. Embora os flocos não sejam prejudiciais ...

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Nature of Polyphenol−Protein Interactions

Cited by 642 publications

References 16 publications

A single dose of tea with or without milk increases plasma antioxidant activity in humans

A single dose of tea with or without milk increases plasma antioxidant activity in humans

In vitro antioxidant and pancreatic α-amylase inhibitory activity of isolated fractions from water extract of Qingzhuan tea

Compostos nitrogenados em bebidas destiladas: cachaça e tiquira

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