Antioxidants from Steamed Used Tea Leaves and Their Reaction Behavior

Nomizu, Kayoko; Hashida, Koh; Makino, Rei; Ohara, Seiji

doi:10.1271/bbb.70762

Cited by 13 publications

(8 citation statements)

References 15 publications

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“…It was assumed that phydroxybenzoic acid is relatively stable when heated, as compared to gallic acid, which has a pyrogallol nucleus in a molecule, and that p-hydroxybenzoic acid is formed during s u b c r i t i c a l w a t e r e x t r a c t i o n b y h y d r o l y z i n g ph y d r o x y b e n z o i c a c i d e s t e r s e x i s t i n g i n l i g n i n molecules (Haghighat Khajavi et al 2006, Khuwijitjaru et al 2004, Pourali et al 2010, Tomimura 1992. Tannins and other components are also potentially the origin of phydroxybenzoic acid, which is formed by the hydrolysis of esters in tannin and other molecules (Nomizu et al 2008 the extracts peaked at 200°C, and the total phenol content peaked at 200-250°C (Wiboonsirikul et al 2007); these results resembled those we obtained for subcritical water extraction using the oil palm trunk. The effect of extraction time on the yields of PDC precursors at 200°C is shown in Fig.…”

Section: Optimum Conditions For Subcritical Water Extraction Of Pdc Psupporting

confidence: 83%

Subcritical Water Extraction of Low-molecular-weight Phenolic Compounds from Oil Palm Biomass

Kawamura

Saary

Hashim

et al. 2014

JARQ

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Subcritical water extraction of low-molecular-weight phenolic compounds from oil palm biomass (trunk, bark, petiole, rachis, leaves, empty fruit bunch fiber, midrib spine leaflets, stalk of fruit bunches, flesh, kernel shells, and albumen) was conducted. It was elucidated that gallic acid, protocatechuicaldehyde, p-hydroxybenzoic acid, p-hydroxybenzaldehyde, vanillic acid, syringic acid, vanillin, syringaldehyde p-coumaric acid and ferulic acid, all of which could be used as 2-pyrone-4,6-dicarboxylic acid (PDC) precursors, were contained in all parts of oil palm, although their composition differed. The peak yield of p-hydroxybenzoic acid was obtained among the PDC precursors. With regard to extraction conditions, temperature: 200°C, time: 20-60 min, and liquor ratio: 50-125 were the most efficient. The kernel shell exhibited the highest yield of PDC precursors, followed by the trunk, empty fruit bunch fiber, and bark. The results of our study indicate the oil palm is a potentially valuable source of PDC precursors.

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Section: Optimum Conditions For Subcritical Water Extraction Of Pdc Psupporting

confidence: 83%

Subcritical Water Extraction of Low-molecular-weight Phenolic Compounds from Oil Palm Biomass

Kawamura

Saary

Hashim

et al. 2014

JARQ

Self Cite

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“…Because it has been reported that the bulk VGCF has about 10 −3 Ωcm as an electrical resistivity [10]. As removal methods for catechin, a pyrolysis method [11,12] and a washing method [13] have been reported, respectively. In the pyrolysis process, catechin is pyrolyzed from about 200 • C by using steam [11,12].…”

Section: Resultsmentioning

confidence: 99%

“…As removal methods for catechin, a pyrolysis method [11,12] and a washing method [13] have been reported, respectively. In the pyrolysis process, catechin is pyrolyzed from about 200 • C by using steam [11,12]. However, such proposed methods can not be applied to our composite samples because the normal papers are used as substrates.…”

Section: Resultsmentioning

confidence: 99%

Fabrication of Aligned-Carbon-Nanotube-Composite Paper with High and Anisotropic Conductivity

Fujitsuka

Oya

2012

Journal of Nanotechnology

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A functional carbon-nanotube (CNT)-composite paper is described in which the CNTs are aligned. This “aligned-CNT composite paper” is a flexible composite material that has CNT functionality (e.g., electrical conductivity) despite being a paper. An advanced fabrication method was developed to overcome the problem of previous CNT-composite papers, that is, reduced conductivity due to random CNT alignment. Aligning the CNTs by using an alternating current (AC) field was hypothesized to increase the electrical conductivity and give the paper an anisotropic characteristic. Experimental results showed that a nonionic surfactant was not suitable as a CNT dispersant for fabricating aligned-CNT composite paper and that catechin with its six-membered rings and hydrophilic groups was suitable. Observation by scanning electron microscopy of samples prepared using catechin showed that the CNTs were aligned in the direction of the AC field on the paper fibers. Measurement of the electric conductivity showed that the surface resistance was different between the direction of the aligned CNTs (high conductivity) and that of verticality (low). The conductivity of the aligned-CNT-composite paper samples was higher than that of nonaligned samples. This unique and functional paper, which has high and anisotropic conductivity, is applicable to a conductive material to control the direction of current.

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“…7 Some studies have demonstrated that excessive production of free radicals and reactive oxygen species, such as hydrogen peroxide (H 2 O 2 ), is indeed harmful, promotes aging, and can strongly influence the development of many diseases such as cancer 8 as well as cardiovascular and neurodegenerative disorders. [9][10][11] Tea polyphenols are retained in the brain and may exert neuroprotective effects whenever their consumption is controlled. 12 In fact, prolonged green tea ingestion is able to significantly protect hippocampal proteins and lipids against oxidative damage.…”

Section: Introductionmentioning

confidence: 99%

Genoprotective Effects of the Green Tea-Derived Polyphenol/Epicatechin Gallate in C6 Astroglial Cells

Abib

Quincozes‐Santos²,

Zanotto³

et al. 2010

Journal of Medicinal Food

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In vitro and in vivo studies have recently reported significant chemopreventive effects of green tea-derived polyphenols in different diseases. However, it remains unclear how such effects could be triggered. In order to elucidate the effects of epicatechin gallate (ECG) in C6 cells, both by itself and against H₂O₂-induced genotoxicity, measurements of DNA strand breaks and chromosome loss were performed. DNA damage was measured by comet and micronucleus assays. The present study shows for the first time how ECG, the major green tea-derived polyphenol, is able to exert dose-dependent genoprotective effects in an H₂O₂-induced toxicity model of C6 astroglial cells. We demonstrate that doses of ECG in a range from 0.1 to 1 μM were able to completely prevent H₂O₂-induced genotoxicity in vitro. In contrast, considerably higher concentrations of ECG (10 μM) were able to reverse previous positive effects in a dose- and time-dependent manner. The same results were confirmed by both comet (F(3,9) = 336,148; P < .001) and micronucleus (F(3,9) = 23,228; P < .001) methods. Together, our data show ECG as a dose-dependent genoprotective compound in C6 astroglial cells. This indicates that small doses of polyphenols included in our diet could have beneficial effects on neural cells, contributing to prevention of oxidative stress-associated brain pathologies. In addition, our data highlight the importance of strictly modulating doses and/or consumption of antioxidant-fortified foods or additional supplements containing such beneficial molecules.

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Antioxidants from Steamed Used Tea Leaves and Their Reaction Behavior

Cited by 13 publications

References 15 publications

Subcritical Water Extraction of Low-molecular-weight Phenolic Compounds from Oil Palm Biomass

Subcritical Water Extraction of Low-molecular-weight Phenolic Compounds from Oil Palm Biomass

Fabrication of Aligned-Carbon-Nanotube-Composite Paper with High and Anisotropic Conductivity

Genoprotective Effects of the Green Tea-Derived Polyphenol/Epicatechin Gallate in C6 Astroglial Cells

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