Determination of tea catechins

Dalluge, Joseph J.; Nelson, Bryant C.

doi:10.1016/s0021-9673(00)00062-5

Cited by 167 publications

(101 citation statements)

References 67 publications

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“…IR spectra were measured in the range 4000-400 cm -1 with KBr pellets, using a Perkin-Elmer 781 spectrometer. 1 H NMR analysis of the ligand was carried out with a Bruker 200 MHz spectrometer in CDCl 3 chloroform, at 25 o C. Chemical shifts were referenced to tetramethylsilane (TMS).…”

Section: Apparatusmentioning

confidence: 99%

“…anti-inflammatory, anti-obesity, reduced incidence of a variety of cancers and cardiovascular diseases) of consuming green tea have been demonstrated. [1][2][3][4] These have been attributed to caffeine, phenolic compounds and anti-oxidative components. The most common polyphenols in green tea are catechins, which may reach concentration levels of 30% (by mass) of dry material.…”

Section: Introductionmentioning

confidence: 99%

“…[1][2][3][4][5][6][7][8][9] High-performance liquid chromatography and capillary electrophoresis with ultraviolet detection are the most cited techniques for separation, identification and quantitation. However, mass spectrometry, and electrochemical, fluorescence and chemiluminescence detection are also used in cases where more sensitive or selective detection is needed.…”

Section: Introductionmentioning

confidence: 99%

“…Analytical techniques, such as gas chromatography, spectrophotometry, nuclear magnetic resonance spectroscopy and biosensors have also been used for the determination of catechin. [1][2][3][4][5][6][7][8][9] The development of functional models of metalloenzymes for catalyst oxidation reactions is a subject of great interest. [10][11][12][13][14][15][16] Neves et al [17][18][19][20][21][22][23][24][25] have extensively synthesized and characterized model complexes to mimic the active site of the different enzymes (e.g., catechol oxidase, peroxidase, galactose oxidase, catalase, purple acid phosphatase).…”

Section: Introductionmentioning

confidence: 99%

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Determination of catechin in green tea using a catechol oxidase biomimetic sensor

Fernandes

Osório

Anjos

et al. 2008

J. Braz. Chem. Soc.

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Um sensor biomimético catecol oxidase, baseado em um novo complexo cobre(II) foi desenvolvido para determinação de catequina em chá verde e os resultados comparados com os obtidos por eletroforese capilar. O complexo dinuclear de cobre(II) [Cu 2 (HL)(µ-CH 3 COO)] (ClO 4 ), contendo o ligante N,N-[bis-(2-piridilmetil)]-N',N'-[(2-hidroxibenzil)(2-hidroxi-3,5-di-tert-butilbenzil)]-1,3-propanodiamino-2-ol (H 3 L), foi sintetizado e caracterizado por IV, 1 H RMN e análise elementar. As melhores condições para otimização do sensor biomimético foram estabelecidas por voltametria de onda quadrada. O melhor desempenho desse sensor foi obtido em 75:15:10% (m/m/m) de pó de grafite:nujol:complexo de cobre(II), tampão fosfato 0,05 mol L -1 (pH 7,5) e freqüência, amplitude de potencial, incremento em 30 Hz, 80 mV, 3,3 mV, respectivamente. A curva analítica foi linear na faixa de concentração 4,95 × 10 -6 a 3,27 × 10 -5 mol L -1 (r=0,9993) com limite de detecção de 2,8 × 10 -7 mol L -1 . Esse sensor biomimético demonstrou longo tempo de estabilidade (9 meses; 800 determinações) e reprodutibilidade com um desvio padrão relativo de 3,5%. A recuperação da catequina em amostras de chá verde variou de 93,8 a 106,9% e a determinação, comparada com a obtida usando eletroforese capilar, mostrou-se aceitável a um nível de confiança de 95%.A catechol oxidase biomimetic sensor, based on a novel copper(II) complex, was developed for the determination of catechin in green tea and the results were compared with those obtained by capillary electrophoresis. The dinuclear copper(II) complex, [Cu 2 (HL)(µ-CH 3 COO)](ClO 4 ), containing the ligand N,N-[bis-(2-pyridylmethyl)]-N',N'-[(2-hydroxybenzyl)(2-hydroxy-3,5-ditert-butylbenzyl)]-1,3-propanediamine-2-ol (H 3 L), was synthesized and characterized by IR, 1 H NMR and elemental analysis. The best conditions for the optimization of the biomimetic sensor were established by square wave voltammetry. The best performance for this sensor was obtained in 75:15:10% (m/m/m) of the graphite powder:nujol:copper(II) complex, 0.05 mol L -1 phosphate buffer solution (pH 7.5) and frequency, pulse amplitude, scan increment at 30 Hz, 80 mV, 3.3 mV, respectively. The analytical curve was linear in the concentration range 4.95 × 10 -6 to 3.27 × 10 -5 mol L -1 (r = 0.9993) with a detection limit of 2.8 × 10 -7 mol L -1 . This biomimetic sensor demonstrated long-term stability (9 months; 800 determinations) and reproducibility with a relative standard deviation of 3.5%. The recovery of catechin from green tea samples ranged from 93.8 to 106.9% and the determination, compared with that obtained using capillary electrophoresis, was found to be acceptable at the 95% confidence level.Keywords: catechin, green tea, biomimetic sensor, square wave voltammetry IntroductionTea is one of the most consumed beverages in the world and was firstly used in China for its medicinal properties 5000 years ago. Recent epidemiological studies have shown that the consumption of tea may help to prevent cancers in humans because the tea l...

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Section: Apparatusmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Determination of catechin in green tea using a catechol oxidase biomimetic sensor

Fernandes

Osório

Anjos

et al. 2008

J. Braz. Chem. Soc.

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“…Their potential health benefits, such as inhibitory effects against cancer and prevention of cardiovascular disease, have been extensively documented on a scientific basis [1]. It is generally believed that catechin flavonoids, whose content is around 60 mg/g of the dry leaf weight [2], possess antioxidant properties and biological activity responsible for the claimed therapeutic activity of tea [3,4]. For this reason, it is important to develop efficient analytical methods able to assess the nature and amount of catechins in various tea extract samples.…”

Section: Introductionmentioning

confidence: 99%

High throughput qualitative analysis of polyphenols in tea samples by ultra-high pressure liquid chromatography coupled to UV and mass spectrometry detectors

Guillarme

Casetta

Bicchi

et al. 2010

Journal of Chromatography A

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a b s t r a c tThe analysis of polyphenols in tea extracts is important due to their potential health benefits. Therefore, efficient and high throughput analytical methods have been developed for the separation of seven predominant polyphenols, also known as catechin derivatives, present in tea extracts. Columns packed with sub-2-m particles operating at elevated pressure (UHPLC strategy) were selected to improve chromatographic performance. The potential of UHPLC-UV was demonstrated with baseline resolution of all standard catechins in only 30 s using a 50-mm column packed with 1.7-m particles. When dealing with real samples such as tea extracts, however, longer columns of up to 150 mm in length were employed to enhance the separation of catechin derivatives and other constituents within the tea samples while maintaining an acceptable analysis time. Two strategies based on 2-D experiments were proposed to clearly identify catechins. Firstly, a liquid-liquid extraction procedure was added prior to the UHPLC-UV analysis to decrease the complexity of the sample. Secondly, UHPLC was coupled to ESI-MS/MS to attain sufficient sensitivity and selectivity between catechin derivatives and other constituents of tea extract. These two strategies were found extremely promising as a clear discrimination of catechins from the matrix could be attained.

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Phytochem. Anal.

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Determination of tea catechins

Cited by 167 publications

References 67 publications

Determination of catechin in green tea using a catechol oxidase biomimetic sensor

Determination of catechin in green tea using a catechol oxidase biomimetic sensor

High throughput qualitative analysis of polyphenols in tea samples by ultra-high pressure liquid chromatography coupled to UV and mass spectrometry detectors

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