7 research outputs found

    Probing the polyphenolic components and alkali-generated radicals reactivity in the studied extract using EPR spectroscopy.

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    <p><b>A.</b> Time dependence of such generated radicals between 2 min (dead time due to spectrometer calibration prior measuring) and 20 min, at about 1.8 minutes interval. <b>B.</b> The dominant spectral fingerprint of the chlorogenic acid is visible in the extract with minor contributions of rutin and quercetin. Ferulic and coumaric acids gives no EPR spectrum while treated with sodium hydroxide as described in experimental section. The best fit for the EPR spectrum of the extract was obtained by a linear combination of the identified polyphenols in a 1/30/40 ratio (quercetin/rutin/chlorogenic acid) (model).</p

    HPLC-UV-vis analysis of the unhydrolysed and hydrolysed <i>G verum</i> extract.

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    <p>(A) Heatmap of the chromatographic profile versus elution time. (<b>B</b>) Chromatograms of the two extracts and of the standards monitored at 320 nm. (<b>C</b>) UV-vis molecular absorption spectra of six of the employed standards.</p

    Phytoconstituent classification based on spectral similarities after chromatographic separation.

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    <p>Score plots of the first two principal components after applying PCA on the UV-vis mean spectra of the chromatographic peaks obtained by HPLC analysis of <i>G</i>. <i>verum</i> extract prior hydrolysis (<b>A</b>) and after hydrolysis (<b>B</b>). The UV-vis spectra of the two extracts, before separation and the standards are also indicated in both plots. The letter U stands for “unhydrolysed” and indicates compounds specific for this extract; the letter H stands for “hydrolysed” and indicates compounds found only in the hydrolysed extract, while the numbers lacking a letter indicate compounds that are found in both extracts. The number is attributed according to the retention order; the compounds are listed in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0200022#pone.0200022.t002" target="_blank">Table 2</a>.</p

    Evaluation of the pro-oxidant activity of the studied extract.

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    <p>The oxyHb (25 μM) is readily oxidized into met form in the presence of the extract (0.2 μg/mL final concentration) and laccase (100 nM) (<b>A</b>). Comparison between the prooxidant reactivity of the identified components of the extract all at the same molar concentration (5 μM) (<b>B</b>), their mixture in same ratios as in the extract prior hydrolysis (standard mixture 1) and after hydrolysis (standard mixture 2) and of the two analysed extracts (<b>C</b>). The comparison of the kinetic profile of the oxyHb oxidation in the presence of the two extracts and laccase depicted as first derivative of the measured curves (<b>D</b>).</p
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