Contribution of Individual Polyphenols to Antioxidant Activity of <i>Cotoneaster bullatus</i> and <i>Cotoneaster zabelii</i> Leaves-Structural Relationships, Synergy Effects and Application for Quality Control
<i>Cotoneaster</i> plants are sources of traditional medicines and dietary products, with health benefits resulting from their phenolic contents and antioxidant activity. In this work, active markers of the leaves of <i>C. bullatus</i> and <i>C. zabelii</i> were c...
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| Main Authors: | , , , , |
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| Format: | Book |
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MDPI AG,
2020-01-01T00:00:00Z.
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| Summary: | <i>Cotoneaster</i> plants are sources of traditional medicines and dietary products, with health benefits resulting from their phenolic contents and antioxidant activity. In this work, active markers of the leaves of <i>C. bullatus</i> and <i>C. zabelii</i> were characterized and evaluated in an integrated phytochemical and biological activity study. Based on UHPLC-PDA-ESI-MS<sup>3</sup> analysis, twelve analytes were preselected from the constituents of the hydromethanolic leaf extracts, and two of them—caffeoylmalic acid and quercetin 3--<i>O</i>-β-<span style="font-variant: small-caps;">d</span>-(2″--<i>O</i>-β-<span style="font-variant: small-caps;">d</span>-xylopyranosyl)galactopyranoside (QPH)—were isolated for full identification (NMR spectroscopy: <sup>1</sup>H, <sup>13</sup>C, COSY, HMBC, HMQC). All selected phenolics contributed to the antioxidant activity of the extracts, which was demonstrated in chemical in vitro tests (DPPH, FRAP, and TBARS) and in a biological model of human plasma exposed to oxidative/nitrative stress induced by peroxynitrite. This contribution was partly due to the synergy between individual polyphenols, evidenced by an isobolographic analysis of the interactions of (−)-epicatechin, chlorogenic acid, and QPH as representatives of three classes of <i>Cotoneaster</i> polyphenols. All twelve markers, including also neochlorogenic acid, cryptochlorogenic acid, procyanidin B2, procyanidin C1, rutin, hyperoside, isoquercitrin, and quercitrin, were thus applied as calibration standards, and a fast, accurate, reproducible, and fully validated RP-HPLC-PDA method for quality control and standardization of the target extracts was proposed. |
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| Item Description: | 2076-3921 10.3390/antiox9010069 |