scholarly journals Isolation of N-Ethyl-2-pyrrolidinone-Substituted Flavanols from White Tea Using Centrifugal Countercurrent Chromatography Off-Line ESI-MS Profiling and Semi-Preparative Liquid Chromatography

Molecules ◽  
2021 ◽  
Vol 26 (23) ◽  
pp. 7284
Author(s):  
Weidong Dai ◽  
Maria Ramos-Jerz ◽  
Dongchao Xie ◽  
Jiakun Peng ◽  
Peter Winterhalter ◽  
...  
Keyword(s):  
Liquid Chromatography ◽  
Ethyl Acetate ◽  
Epigallocatechin Gallate ◽  
Partition Ratio ◽  
Reversed Phase ◽  
Size Exclusion ◽  
Esi Ms ◽  
White Tea ◽  
Solvent Systems

N-Ethyl-2-pyrrolidinone-substituted flavanols (EPSF) are marker compounds for long-term stored white teas. However, due to their low contents and diasteromeric configuration, EPSF compounds are challenging to isolate. In this study, two representative epimeric EPSF compounds, 5′′′R- and 5′′′S-epigallocatechin gallate-8-C N-ethyl-2-pyrrolidinone (R-EGCG-cThea and S-EGCG-cThea), were isolated from white tea using centrifugal partition chromatography (CPC). Two different biphasic solvent systems composed of 1. n-hexane – ethyl acetate – methanol – water (1:5:1:5, v/v/v/v) and 2. n-hexane – ethyl acetate – acetonitrile – water (0.7:3.0:1.3:5.0, v/v/v/v) were used for independent pre-fractionation experiments; 500 mg in each separation of white tea ethyl acetate partition were fractionated. The suitability of the two solvent systems was pre-evaluated by electrospray mass-spectrometry (ESI-MS/MS) analysis for metabolite distribution and compared to the results of the CPC experimental data using specific metabolite partition ratio KD values, selectivity factors α, and resolution factors RS. After size-exclusion and semi-preparative reversed-phase liquid chromatography, 6.4 mg of R-EGCG-cThea and 2.9 mg of S-EGCG-cThea were recovered with purities over 95%. Further bioactivity evaluation showed that R- and S-EGCG-cThea possessed in vitro inhibition effects on α-glucosidase with IC50 of 70.3 and 161.7 μM, respectively.

scholarly journals Bioactive Compounds and Antioxidant Activity of Mango Peel Liqueurs (Mangifera indica L.) Produced by Different Methods of Maceration

Antioxidants ◽  
2019 ◽  
Vol 8 (4) ◽  
pp. 102 ◽  
Author(s):  
Emanuela Monteiro Coelho ◽  
Marcelo Eduardo Alves Olinda de Souza ◽  
Luiz Claudio Corrêa ◽  
Arão Cardoso Viana ◽  
Luciana Cavalcanti de Azevêdo ◽  
...  
Keyword(s):  
Antioxidant Activity ◽  
Bioactive Compounds ◽  
High Performance ◽  
Mangifera Indica ◽  
Epigallocatechin Gallate ◽  
Reversed Phase ◽  
Epicatechin Gallate ◽  
Bioactive Content ◽  
Mango Peels

The present work had the objective of producing liqueurs from mango peels (varieties “Haden” and “Tommy Atkins”) by processes of alcoholic maceration and maceration with pectinase, as well as to evaluate bioactive compounds by reversed-phase high-performance liquid chromatography coupled to diode array detection and fluorescence-detection (RP-HPLC/DAD/FD) and in vitro antioxidant activity (AOX), for by-product potential reuse. Alcoholic maceration in wine ethanol (65% v/v) produced liqueurs with higher phytochemical and AOX content. Maceration with pectinase resulted in liqueurs with higher quercetin-3-O-glucopyranoside content. In relation to mango varieties, Haden liqueurs presented higher bioactive content than Tommy Atkins liqueurs. The liqueurs presented high antioxidant activity. The main bioactive compounds found were flavanols (epicatechin-gallate, epigallocatechin-gallate), flavonols (quercetin-3-O-glucopyranoside and rutin), and phenolic acids (gallic acid, o-coumaric acid, and syringic acid). The present study showed that the production of liqueur enabled the recovering of an important part of the bioactive content of mango peels, suggesting an alternative for the recovery of antioxidant substances from this by-product.

scholarly journals Determination of Imidacloprid and Benzimidazole Residues in Fruits and Vegetables by Liquid Chromatography–Mass Spectrometry after Ethyl Acetate Multiresidue Extraction

2000 ◽  
Vol 83 (3) ◽  
pp. 748-755 ◽  
Author(s):  
Amadeo R Fernández-Alba ◽  
Ana Tejedor ◽  
Ana Agüera ◽  
Mariano Contreras ◽  
Juan Garrido
Keyword(s):  
Mass Spectrometry ◽  
Liquid Chromatography ◽  
Ethyl Acetate ◽  
Fruits And Vegetables ◽  
Monitoring Program ◽  
Reversed Phase ◽  
Food Samples ◽  
Ionization Mass ◽  
Vegetables And Fruits

Abstract A simple and sensitive method based on liquid chromatography–atmospheric pressure ionization–mass spectrometry is described for the determination of 4 benzimidazole pesticides (carbendazim, thiabendazole, benomyl, and thiophanate-methyl) and imidacloprid in vegetables and fruits. Food samples were typically extracted with ethyl acetate to draw the analytes into the organic phase. No cleanup step was necessary before injection into the liquid chromatographic (LC) system with electrospray mass spectrometric detection. The analytes were separated on a reversed-phase C8LC column. Limits of detection for the compounds were in the μg/L range. Results are reported for validation studies with fortified pear and tomato samples and for residues of the target compounds found in the pesticide residue monitoring program during 1998.

Chromatographic behaviour of some porphyrins and their complexes with Zn, Pd(II) and Cu(II)

2000 ◽  
Vol 04 (02) ◽  
pp. 209-214 ◽  
Author(s):  
M. I. UVAROVA ◽  
G. D. BRYKINA ◽  
O. A. SHPIGUN
Keyword(s):  
High Performance Liquid Chromatography ◽  
Liquid Chromatography ◽  
Ethyl Acetate ◽  
Mobile Phase ◽  
High Performance ◽  
Reversed Phase ◽  
Zinc Complexes ◽  
Acetate Concentration ◽  
Hydrophobic Compounds ◽  
Retention Parameters

In this work the influence of the porphyrin structure and of the nature of the mobile phase upon retention parameters is examined by means of reversed phase high-performance liquid chromatography (HPLC). Acetonitrile–ethyl acetate and other mixtures were used as eluents. An increase in the retention of azo- and benzosubstituted porphyrins as well as of those containing a large number of carbon atoms as substituents of macrocycles may be noted. A variation in the polarity of the mobile phase affects the retention of the ligands more than that of their zinc complexes. The retention of the most hydrophobic compounds may be well described in coordinates lg k'– lg M. For less hydrophobic porphyrins these dependences are close to linear only within limited intervals of mobile phase ethyl acetate concentration. The best separation of zinc complexes was achieved with acetonitrile as the eluent. The detection limit of porphyrin ligands and complexes with metals is n × 10-8 M.

Separation of Liquiritin by Two-Dimensional Liquid Chromatography

2012 ◽  
Vol 455-456 ◽  
pp. 1232-1238 ◽  
Author(s):  
Jing Xiang Cong ◽  
Shao Yan Wang ◽  
Hong Gao
Keyword(s):  
Liquid Chromatography ◽  
Reversed Phase ◽  
Normal Phase ◽  
Size Exclusion ◽  
Two Dimensional ◽  
Target Compound ◽  
Reversed Phase Chromatography ◽  
Complex Samples ◽  
Exclusion Chromatography ◽  
Licorice Extract

Two-dimensional liquid chromatography (2DLC) is an important technology for the separation and analysis of complex samples. Liquiritin, an important active component in licorice, was chosen as the target compound and it was separated by three kinds of off-line 2DLC, i.e. size exclusion chromatography × reversed phase chromatography, normal phase × reversed phase chromatography and reversed phase chromatography × reversed phase chromatography (SEC×RP, NP×RP and RP×RP). The chromatographic conditions were selected and the 2D systems were combined. The results show that it is feasible to separate Liquiritin from licorice extract using 2DLC. Among the 2D modes mentioned above, the highest purity of Liquiritin was obtained in the RP×RP mode, and the concentration of Liquiritin was increased most significantly in the NP×RP mode.

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