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.S. Plant Soil 2003 252 385 395 J.B. Harborne , Biochemistry of phenolic compounds

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Phenolic compounds, such as flavonoids and phenolic acids, are very important substances that occur in various medicinal plants. They show different pharmacological activities which might be useful in the therapy of many diseases. Phenolic compounds have achieved an increasing interest over the last years because these compounds are easily oxidized and, thus, act as strong antioxidants. We present the chemiluminescence of different phenolic compounds measured directly on high-performance thin-layer chromatography LiChrospher® plates using the oxalic acid derivative bis(2,4,6-trichlorophenyl) oxalate (TCPO) in conjunction with H2O2. Our results indicate that chemiluminescence intensity increases with an ascending number of phenolic groups in the molecule. The method can be used to detect phenolic compounds in beverages like coffee, tea, and wine.

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Dendrophthoe falcata (Linn. f.) Etting. is a stem parasite commonly known as ‘ Vanda ’ in the Ayurvedic system of medicine. A TLC method has been established for simultaneous identification and quantification of phenolic compounds in different parts of this plant. Chromatography was performed on silica gel with tolueneethyl acetate-formic acid 6:4:1 ( v/v ) as mobile phase, and characteristic bands of (+)-catechin, ellagic acid, quercetin, and ferulic acid were observed at R F 0.35, 0.41, 0.63, and 0.66, respectively. The method was validated for precision, repeatability, and accuracy. The method enables reliable quantification with good resolution and separation from other constituents of the plant extract. The accuracy of the method was checked by measuring recovery of all four phenolic compounds at three different concentrations and by matching the spectra of reference markers with those of the corresponding bands in the extract at three different positions, i.e. the start, apex, and end positions of the band. The presence and quantity of these phenolic compounds varies from part to part of this parasitic plant. For example, quercetin was present only in the leaves, ferulic acid in the stem, and ellagic acid and (+)-catechin in stem and root. More (+)-catechin and ellagic acid were found in the stem than in the root.

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Separation selectivity has been optimized in two-dimensional thin-layer chromatography (2D TLC) by connecting diol or silica plates (on which NP chromatograms were developed) to RP-18W plates (on which reversed-phase chromatograms were developed). Retention of test substances was investigated to select optimum chromatographic systems for separation of selected phenolic compounds by 2D TLC. Selection of optimal mobile phases was performed on the basis of plots of retention against mobile phase composition. The next step of the optimization was calculation of statistical data for correlation of R M values for pairs of chromatographic systems — NP diol-RP C 18 or silica-RP C 18 . Orthogonal chromatographic systems were selected on the basis of these correlations and used to separate phenolic compounds present in plant extracts. For example, extracts from Polygonum sp. and Verbascum sp. were separated by use of optimum 2D TLC systems.

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A novel liquid-phase microextraction method coupled with high-performance thin-layer chromatography (HPTLC) for preconcentration, separation, and determination of six phenolic compounds in water samples has been developed. Target analytes were extracted using microliter volume of 1-undecanol, which floated on the surface of the aqueous sample and was separated on an RP-18 F254 HPTLC plate using a mixture of methanol-water 2:1 (%, v/v) as the mobile phase. The plates were developed vertically up to a distance of 80 mm. The calibration curves were linear in the range of 0.025–4.0 and 0.1–20.0 mg per band, with good coefficient of determinations of 0.9978–0.9991 and 0.9985–0.9995, for phenol (PN), 2-chlorophenol (2-CP), 2,4-dichlorophenol (2,4-DCP), 2,4,6-trichlorophenol (2,4,6-TCP), 2,3,4,6-tetrachlorophenol (2,3,4,6-TeCP), and pentachlorophenol (PCP). The limit of detection (LOD) and limit of quantification (LOQ) values of the six investigated compounds were between 8–35 and 25–98 ng per band, respectively. The relative standard deviations for repeatability were between 2.61% and 6.35%. The accuracy of the method was checked by the determination of recovery at three different levels, and varied from 89.21% to 101.74% with RSD% of 2.07–6.73% (n = 3).

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pyriformis using different solvents. J. Fd Sci. Technol. , 1–5 , DOI: 10.1007/s13197-012-0759-z Haminiuk, C.W.I., Maciel, G.M., Plata-Oviedo, M.S.V. & Peralta, R.M. (2012b): Phenolic compounds in

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Acta Alimentaria
Authors: B. Nótin, M. Stéger-Máté, R. Juhász, D. Jakab, J. Monspart-Sényi, and J. Barta

Robards, K., Prenzler, P.D., Tucker, G., Swatsitang, P. & Glover, W. (1999): Phenolic compounds and their role in oxidative processes in fruits. Fd Chem. , 66 , 401–436. Glover W

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Acta Chromatographica
Authors: Milica Atanacković Krstonošić, Jelena Cvejić Hogervorst, Mira Mikulić, and Ljiljana Gojković-Bukarica

1. Introduction Phenolic compounds are widely present among natural products, and they can express different beneficial biological activities. Some of them include antioxidant, cardioprotective, anticancer, anti

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Acta Alimentaria
Authors: M. Atanacković Krstonošić, J. Cvejić Hogervorst, Lj. Torović, V. Puškaš, U. Miljić, M. Mikulić, and Lj. Gojković Bukarica

, Y. , T ian , Y. , L iu , D. , L i , Z. , Z hang , X.X. , L i , J. M. , H uang , J.H. , W ang , J. & P an , Q.H. ( 2015 ): Evolution of phenolic compounds and sensory in bottled red wines and their co-development . Food Chem

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activity and total phenolic compounds in extracts of selected grasses (Poaceae) . Herba Polonica 55 , 214 – 221 . 3. Cipollini , D. , Stevenson , R. , Enright , S

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