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Hplc analysis of tea

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https://www.readbyqxmd.com/read/29120758/antioxidant-capacity-and-major-polyphenol-composition-of-teas-as-affected-by-geographical-location-plantation-elevation-and-leaf-grade
#1
Chuang Zhang, Claire Li-Chieh Suen, Chao Yang, Siew Young Quek
Tea polyphenols have been a topic of discussion due to their health benefits. Nevertheless, detailed studies on the antioxidant capacity and polyphenol contents of teas in relation to factors including geographical locations, plantation elevations and leaf grades have been limited. In this study, 53 tea samples were analysed to determine the individual and total catechin and theaflavin contents by HPLC and the total antioxidant capacity by Oxygen Radical Absorbance Capacity (ORAC) methods. Results show that the polyphenol (catechins and theaflavins) contents were significantly influenced by plantation location...
April 1, 2018: Food Chemistry
https://www.readbyqxmd.com/read/29100264/microwave-mediated-synthesis-and-analytical-method-development-for-the-estimation-of-novel-1-4-dihydropyridines-in-bulk-by-rp-hplc
#2
Anupreet Kaur, Jaspreet Kaur, Ranju Bansal
The present work describes a rapid and green microwave mediated method for the synthesis and a simple and precise isocratic reverse phase HPLC method for the estimation of the biologically significant dihydropyridines. The conventional synthesis of these dihydropyridines has been previously reported from our lab. The analysis of a standard solution (1 mg/ml) was accomplished on a symmetry (4.6 mm I.D x 250 mm) C-18 column using mobile phase acetonitrile:water:triethylamine (TEA) (70:30:0.1 v/v/v) at a flow rate of 0...
November 3, 2017: Drug Research
https://www.readbyqxmd.com/read/28964516/new-potentially-antihypertensive-peptides-liberated-in-milk-during-fermentation-with-selected-lactic-acid-bacteria-and-kombucha-cultures
#3
Ebrahim Elkhtab, Mohamed El-Alfy, Mohamed Shenana, Abdelaty Mohamed, Ahmed E Yousef
Compounds with the ability to inhibit angiotensin-converting enzyme (ACE) are used medically to treat human hypertension. The presence of such compounds naturally in food is potentially useful for treating the disease state. The goal of this study was to screen lactic acid bacteria, including species commonly used as dairy starter cultures, for the ability to produce new potent ACE-inhibiting peptides during milk fermentation. Strains of Lactobacillus acidophilus, Lactobacillus casei, Lactobacillus delbrueckii ssp...
September 27, 2017: Journal of Dairy Science
https://www.readbyqxmd.com/read/28947204/preparation-of-a-reversed-phase-anion-exchange-mixed-mode-spherical-sorbent-by-pickering-emulsion-polymerization-for-highly-selective-solid-phase-extraction-of-acidic-pharmaceuticals-from-wastewater
#4
Chaonan Huang, Yun Li, Jiajia Yang, Junyu Peng, Jing Jin, Dhanjai, Jincheng Wang, Jiping Chen
The present work represents a simple and effective preparation of a novel mixed-mode anion-exchange (MAX) sorbent based on porous poly[2-(diethylamino)ethyl methacrylate-divinylbenzene] (poly(DEAEMA-DVB)) spherical particles synthesized by one-step Pickering emulsion polymerization. The poly(DEAEMA-DVB) particles were quaternized with 1,4-butanediol diglycidyl ether (BDDE) followed by triethylamine (TEA) via epoxy-amine reaction to offer strong anion exchange properties. The synthesized MAX sorbent was characterized by scanning electron microscopy, Fourier-transform infrared spectroscopy, nitrogen adsorption-desorption measurements and elemental analysis...
September 8, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28928532/effect-of-interaction-of-epigallocatechin-gallate-and-flavonols-on-color-alteration-of-simulative-green-tea-infusion-after-thermal-treatment
#5
Qianying Dai, Yuanyuan He, Chit-Tang Ho, Jing Wang, Shujuan Wang, Yue Yang, Liping Gao, Tao Xia
Epigallocatechin gallate (EGCG) and flavonols are important phenolic compounds in green tea. These compounds are sensitive to thermal condition and their structural alteration results in making browning the green tea infusion. This study aimed to research the interaction between EGCG and flavonols during thermal infusion. EGCG and flavonols model solutions were prepared based on concentration in green tea infusion, and their colors appearance and attributes were analyzed in 10 h by thermal treatment. Results showed that kaempferol, quercetin, and myricetin accelerated the oxidation of EGCG and made the model solution browning...
August 2017: Journal of Food Science and Technology
https://www.readbyqxmd.com/read/28895237/a-comprehensive-characterisation-of-rosemary-tea-obtained-from-rosmarinus-officinalis-l-collected-in-a-sub-humid-area-of-tunisia
#6
Mariem Achour, Raquel Mateos, Maha Ben Fredj, Ali Mtiraoui, Laura Bravo, Saad Saguem
INTRODUCTION: Rosemary (Rosmarinus officinalis L.) is an aromatic plant common in Tunisia and it is widely consumed as a tea in traditional cuisine and in folk medicine to treat various illnesses. Currently, most research efforts have been focused on rosemary essential oil, alcoholic and aqueous extracts, however, little is reported on rosemary infusion composition. OBJECTIVE: To investigate compounds present in rosemary tea obtained from Rosmarinus officinalis L...
September 12, 2017: Phytochemical Analysis: PCA
https://www.readbyqxmd.com/read/28890268/acylhydrazone-bond-dynamic-covalent-polymer-gel-monolithic-column-online-coupling-to-high-performance-liquid-chromatography-for-analysis-of-sulfonamides-and-fluorescent-whitening-agents-in-food
#7
Chengjiang Zhang, Xialin Luo, Tianfu Wei, Yufei Hu, Gongke Li, Zhuomin Zhang
A new dynamic covalent polymer (DCP) gel was well designed and constructed based on imine chemistry. Polycondensation of 4,4'-biphenyldicarboxaldehyde and 1,3,5-benzenetricarbohydrazide via Schiff-base reaction resulted in an acylhydrazone bond gel (AB-gel) DCP. AB-gel DCP had three-dimensional network of interconnected nanoparticles with hierarchically porous structure. AB-gel DCP was successfully fabricated as a monolithic column by an in-situ chemical bonding method for online enrichment and separation purpose with excellent permeability...
October 13, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28879218/identification-of-epigallocatechin-3-o-3-o-methyl-gallate-egcg3-me-and-amino-acid-profiles-in-various-tea-camellia-sinensis-l-cultivars
#8
Hyang-Gi Ji, Yeong-Ran Lee, Min-Seuk Lee, Kyeng Hwan Hwang, Eun-Hee Kim, Jun Seong Park, Young-Shick Hong
This article includes experimental data on the identification of epigallocatechin-3-O-(3-O-methyl)-gallate (EGCG3''Me) by 2-dimensional (2D) proton ((1)H) NMR analysis and on the information of amino acid and catechin compound profiles by HPLC analysis in leaf extracts of various tea cultivars. These data are related to the research article "Metabolic phenotyping of various tea (Camellia sinensis L.) cultivars and understanding of their intrinsic metabolism" (Ji et al., 2017) [1]. The assignment for EGCG3x''Me by (1)H NMR analysis was also confirmed with spiking experiment of its pure chemical...
October 2017: Data in Brief
https://www.readbyqxmd.com/read/28863898/the-enhanced-inhibition-of-water-extract-of-black-tea-under-baking-treatment-on-%C3%AE-amylase-and-%C3%AE-glucosidase
#9
Da-Peng Tong, Ke-Xue Zhu, Xiao-Na Guo, Wei Peng, Hui-Ming Zhou
This paper studied the inhibition of water extract of natural or baked black tea on the activity of α-amylase and α- glucosidase. Baking treatment was found to be one effective way to enhance the inhibition of black tea on both α-amylase and α- glucosidase, and IC50 of water extract of baked black tea (BBTWE) were 1.213mg/mL and 4.190mg/mL, respectively, while IC50 of water extract of black tea (BTWE) were 1.723mg/mL and 6.056mg/mL, respectively. This study further studied the mechanism of the effect of water extract on α-amylase and α- glucosidase using HPLC, circular dichroism, and synchronous fluorescence...
August 31, 2017: International Journal of Biological Macromolecules
https://www.readbyqxmd.com/read/28821789/isolation-characterization-and-toxicological-potential-of-alternaria-mycotoxins-tea-aoh-and-ame-in-different-alternaria-species-from-various-regions-of-india
#10
Mukesh Meena, Prashant Swapnil, R S Upadhyay
Alternaria species produce various sorts of toxic metabolites during their active growth and causes severe diseases in many plants by limiting their productivity. These toxic metabolites incorporate various mycotoxins comprising of dibenzo-α-pyrone and some tetramic acid derivatives. In this study, we have screened out total 48 isolates of Alternaria from different plants belonging to different locations in India, on the basis of their pathogenic nature. Pathogenicity testing of these 48 strains on susceptible tomato variety (CO-3) showed 27...
August 18, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28764047/an-integrated-antioxidant-activity-fingerprint-for-commercial-teas-based-on-their-capacities-to-scavenge-reactive-oxygen-species
#11
Yu-Jie Guo, Li-Qiong Sun, Bo-Yang Yu, Jin Qi
An integrated antioxidant activity fingerprint, based on on-line screening methods for three reactive oxygen species (ROS: superoxide anion radical, hydrogen peroxide, and hydroxyl radical) was developed to comprehensively evaluate the quality of 12 batches of commercial tea. High-performance liquid chromatography (HPLC) coupled with a chemiluminescent detector was used to determine the antioxidant characteristics of a selection of teas as bioactivity fingerprints. An HPLC-electrospray ionization-mass spectrometry analysis was used to determine the chemical profiles of the teas in the chromatographic fingerprints...
December 15, 2017: Food Chemistry
https://www.readbyqxmd.com/read/28764022/fast-gradient-hplc-ms-separation-of-phenolics-in-green-tea-to-monitor-their-degradation
#12
Petra Šilarová, Lenka Česlová, Milan Meloun
The degradation of catechins and other phenolics in green tea infusions were monitored using fast HPLC/MS separation. The final separation was performed within 2.5min using Ascentis Express C18 column (50mm×2.1mm i.d.) packed with 2μm porous shell particles. Degradation was studied in relation to the temperature of water (70, 80, 90°C) and the standing time of the infusion (up to 6h). Along with chromatographic separation, the antioxidant properties of the infusions were monitored using two spectrophotometric methods...
December 15, 2017: Food Chemistry
https://www.readbyqxmd.com/read/28666160/on-line-coupling-of-molecularly-imprinted-solid-phase-extraction-with-liquid-chromatography-for-the-fast-determination-of-coumarins-from-complex-samples
#13
Andrea Machyňáková, Ivona Lhotská, Katarína Hroboňová, Dalibor Šatínský
In this work, an on-line SPE-HPLC method with spectrophotometric detection was developed for the determination of coumarins in complex samples. For the on-line cleanup of samples, a molecularly imprinted polymer was packed into the column cartridge and coupled directly with HPLC (MISPE-HPLC) using a column switching system. The separation of coumarins was performed on a C18 core-shell column (100×4.6mm, 5μm) with a mobile phase consisting of 0.3% acetic acid/acetonitrile with gradient elution at a flow-rate of 1mLmin(-1)...
October 25, 2017: Journal of Pharmaceutical and Biomedical Analysis
https://www.readbyqxmd.com/read/28659938/functional-characterization-of-tea-camellia-sinensis-myb4a-transcription-factor-using-an-integrative-approach
#14
Mingzhuo Li, Yanzhi Li, Lili Guo, Niandi Gong, Yongzheng Pang, Wenbo Jiang, Yajun Liu, Xiaolan Jiang, Lei Zhao, Yunsheng Wang, De-Yu Xie, Liping Gao, Tao Xia
Green tea (Camellia sinensis, Cs) abundantly produces a diverse array of phenylpropanoid compounds benefiting human health. To date, the regulation of the phenylpropanoid biosynthesis in tea remains to be investigated. Here, we report a cDNA isolated from leaf tissues, which encodes a R2R3-MYB transcription factor. Amino acid sequence alignment and phylogenetic analysis indicate that it is a member of the MYB4-subgroup and named as CsMYB4a. Transcriptional and metabolic analyses show that the expression profile of CsMYB4a is negatively correlated to the accumulation of six flavan-3-ols and other phenolic acids...
2017: Frontiers in Plant Science
https://www.readbyqxmd.com/read/28649074/neurochemical-and-behavioral-effects-of-green-tea-camellia-sinensis-as-observed-in-animals-exposed-to-restraint-stress
#15
Huma Ikram, Beenish Mirza, Darakhshan Jabeen Haleem
Clinical studies on psychiatric patients suggest that life events stress precipitates depression. The possible involvement of 5-Hydroxy tryptamine (5-HT; Serotonin) in depression and other behavioral deficits is also suggested by clinical studies. As a natural stimulant, green tea (Camellia Sinensis) diminishes stress, worry and anxiety, allowing the brain to focus and concentrate better. Previously we have reported that beneficial effects of green tea might be associated with altered levels of 5-HT, which in turn may help in coping with stress...
March 2017: Pakistan Journal of Pharmaceutical Sciences
https://www.readbyqxmd.com/read/28433057/low-cost-humic-acid-bonded-silica-as-an-effective-solid-phase-extraction-sorbent-for-convenient-determination-of-aflatoxins-in-edible-oils
#16
Neng-Zhi Zhou, Ping Liu, Xiao-Chuan Su, Yan-Hua Liao, Ning-Sheng Lei, Yong-Hong Liang, Shao-Huan Zhou, Wen-Si Lin, Jie Chen, Yu-Qi Feng, Yang Tang
Aflatoxins (AFs) are highly toxic, mutagenic, carcinogenic, and teratogenic secondary metabolites produced by the toxigenic fungi Aspergillus flavus and Aspergillus parasiticus. AFs tend to contaminate a wide range of foods which is a serious and recurring food safety problem worldwide. Currently, immunoaffinity chromatography (IAC) has become the most conventional sample clean-up method for determining AFs in foodstuffs. However, IAC method is limited in the large-scale food analysis because it requires the use of expensive disposable cartridges and the IA procedure is time-consuming...
June 1, 2017: Analytica Chimica Acta
https://www.readbyqxmd.com/read/28393854/transcriptomic-analysis-of-the-biosynthesis-recycling-and-distribution-of-ascorbic-acid-during-leaf-development-in-tea-plant-camellia-sinensis-l-o-kuntze
#17
Hui Li, Wei Huang, Guang-Long Wang, Wen-Li Wang, Xin Cui, Jing Zhuang
Ascorbic acid (AsA), known as vitamin C, is an essential nutrient for humans and mainly absorbed from food. Tea plant (Camellia sinensis (L.) O. Kuntze) leaves can be a dietary source of AsA for humans. However, experimental evidence on the biosynthesis, recycling pathway and distribution of AsA during leaf development in tea plants is unclear. To gain insight into the mechanism and distribution of AsA in the tea plant leaf, we identified 18 related genes involved in AsA biosynthesis and recycling pathway based on the transcriptome database of tea plants...
April 10, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28334752/monitoring-the-consistency-quality-and-antioxidant-activity-of-da-hong-pao-teas-by-hplc-fingerprinting
#18
Lin Wang, Ting Yan, Lanping Yang, Kexia Zhang, Jingming Jia
In the present study, a high performance liquid chromatography (HPLC) method was developed and validated for fingerprint profiling to evaluate the quality consistency of the Da Hong Pao tea. The chromatographic separation was performed on a USA Waters C18 column (4.6 mm × 250 mm, 5 μm, Waters-XBridge Shield RP 18) with gradient elution. The column temperature was maintained at 30°C and the detection wavelength was set at 278 nm. The results demonstrated that the developed HPLC method achieved the desired linearity, precision, accuracy and limit of quantification...
May 1, 2017: Journal of Chromatographic Science
https://www.readbyqxmd.com/read/28208888/haemoglobinopathies-and-%C3%AE-thalassaemia-among-the-tribals-working-in-the-tea-gardens-of-assam-india
#19
Anju Barhai Teli, Rumi Deori, Sidhartha Protim Saikia
INTRODUCTION: Prevalence of haemoglobinopathies and β-thalassaemia are very high in India but information about its status among the tribals working in the tea gardens of Assam is very less. AIM: The present study was carried out to determine the prevalence of haemoglobinopathies and β-thalassaemia among the tribals working in the tea gardens of Assam. MATERIALS AND METHODS: A total 1204 samples from the tribals working in tea gardens of Assam were analysed for both Complete Blood Count (CBC) and High Pressure Liquid Chromatography (HPLC) for detection of haemoglobinopathies and β-thalassaemia...
December 2016: Journal of Clinical and Diagnostic Research: JCDR
https://www.readbyqxmd.com/read/28193433/antioxidant-profiling-of-vine-tea-ampelopsis-grossedentata-off-line-coupling-heart-cutting-hsccc-with-hplc-dad-qtof-ms-ms
#20
Qingping Gao, Ruyi Ma, Lin Chen, Shuyun Shi, Ping Cai, Shuihan Zhang, Haiyan Xiang
Vine tea with strong antioxidant activity is commonly consumed as healthy tea/beverage. However, detailed information about its antioxidants is incomplete. Here, off-line hyphenation of heart-cutting high-speed countercurrent chromatography (HSCCC) with high performance liquid chromatography-diode array detector-quadrupole time-of-flight tandem mass spectrometry (HPLC-DAD-QTOF-MS/MS) were described for systematic profiling antioxidants in vine tea. At first, antioxidants were rapidly screened by 1,1-diphenyl-2-picryl-hydrazyl radical-high performance liquid chromatography (DPPH-HPLC)...
June 15, 2017: Food Chemistry
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