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(−)-Epicatechin—An Important Contributor to the Antioxidant Activity of Japanese Knotweed Rhizome Bark Extract as Determined by Antioxidant Activity-Guided Fractionation

The antioxidant activities of Japanese knotweed rhizome bark extracts, prepared with eight different solvents or solvent mixtures (water, methanol, 80% methanol((aq)), acetone, 70% acetone((aq)), ethanol, 70% ethanol((aq)), and 90% ethyl acetate((aq))), were determined using a 2,2-diphenyl-1-picrylh...

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Autores principales: Jug, Urška, Naumoska, Katerina, Vovk, Irena
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2021
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7832395/
https://www.ncbi.nlm.nih.gov/pubmed/33477734
http://dx.doi.org/10.3390/antiox10010133
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author Jug, Urška
Naumoska, Katerina
Vovk, Irena
author_facet Jug, Urška
Naumoska, Katerina
Vovk, Irena
author_sort Jug, Urška
collection PubMed
description The antioxidant activities of Japanese knotweed rhizome bark extracts, prepared with eight different solvents or solvent mixtures (water, methanol, 80% methanol((aq)), acetone, 70% acetone((aq)), ethanol, 70% ethanol((aq)), and 90% ethyl acetate((aq))), were determined using a 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical-scavenging assay. Low half maximal inhibitory concentration (IC(50)) values (2.632–3.720 µg mL(−1)) for all the extracts were in the range of the IC(50) value of the known antioxidant ascorbic acid at t(0) (3.115 µg mL(−1)). Due to the highest extraction yield (~44%), 70% ethanol((aq)) was selected for the preparation of the extract for further investigations. The IC(50) value calculated for its antioxidant activity remained stable for at least 14 days, while the IC(50) of ascorbic acid increased over time. The stability study showed that the container material was of great importance for the light-protected storage of the ascorbic acid((aq)) solution in a refrigerator. Size exclusion–high-performance liquid chromatography (SEC-HPLC)–UV and reversed phase (RP)-HPLC-UV coupled with multistage mass spectrometry (MS(n)) were developed for fractionation of the 70% ethanol((aq)) extract and for further compound identification, respectively. In the most potent antioxidant SEC fraction, determined using an on-line post-column SEC-HPLC-DPPH assay, epicatechin, resveratrol malonyl hexoside, and its in-source fragments (resveratrol and resveratrol acetyl hexoside) were tentatively identified by RP-HPLC-MS(n). Moreover, epicatechin was additionally confirmed by two orthogonal methods, SEC-HPLC-UV and high-performance thin-layer chromatography (HPTLC) coupled with densitometry. Finally, the latter technique enabled the identification of (−)-epicatechin. (−)-Epicatechin demonstrated potent and stable time-dependent antioxidant activity (IC(50) value ~1.5 µg mL(−1)) for at least 14 days.
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spelling pubmed-78323952021-01-26 (−)-Epicatechin—An Important Contributor to the Antioxidant Activity of Japanese Knotweed Rhizome Bark Extract as Determined by Antioxidant Activity-Guided Fractionation Jug, Urška Naumoska, Katerina Vovk, Irena Antioxidants (Basel) Article The antioxidant activities of Japanese knotweed rhizome bark extracts, prepared with eight different solvents or solvent mixtures (water, methanol, 80% methanol((aq)), acetone, 70% acetone((aq)), ethanol, 70% ethanol((aq)), and 90% ethyl acetate((aq))), were determined using a 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical-scavenging assay. Low half maximal inhibitory concentration (IC(50)) values (2.632–3.720 µg mL(−1)) for all the extracts were in the range of the IC(50) value of the known antioxidant ascorbic acid at t(0) (3.115 µg mL(−1)). Due to the highest extraction yield (~44%), 70% ethanol((aq)) was selected for the preparation of the extract for further investigations. The IC(50) value calculated for its antioxidant activity remained stable for at least 14 days, while the IC(50) of ascorbic acid increased over time. The stability study showed that the container material was of great importance for the light-protected storage of the ascorbic acid((aq)) solution in a refrigerator. Size exclusion–high-performance liquid chromatography (SEC-HPLC)–UV and reversed phase (RP)-HPLC-UV coupled with multistage mass spectrometry (MS(n)) were developed for fractionation of the 70% ethanol((aq)) extract and for further compound identification, respectively. In the most potent antioxidant SEC fraction, determined using an on-line post-column SEC-HPLC-DPPH assay, epicatechin, resveratrol malonyl hexoside, and its in-source fragments (resveratrol and resveratrol acetyl hexoside) were tentatively identified by RP-HPLC-MS(n). Moreover, epicatechin was additionally confirmed by two orthogonal methods, SEC-HPLC-UV and high-performance thin-layer chromatography (HPTLC) coupled with densitometry. Finally, the latter technique enabled the identification of (−)-epicatechin. (−)-Epicatechin demonstrated potent and stable time-dependent antioxidant activity (IC(50) value ~1.5 µg mL(−1)) for at least 14 days. MDPI 2021-01-18 /pmc/articles/PMC7832395/ /pubmed/33477734 http://dx.doi.org/10.3390/antiox10010133 Text en © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Jug, Urška
Naumoska, Katerina
Vovk, Irena
(−)-Epicatechin—An Important Contributor to the Antioxidant Activity of Japanese Knotweed Rhizome Bark Extract as Determined by Antioxidant Activity-Guided Fractionation
title (−)-Epicatechin—An Important Contributor to the Antioxidant Activity of Japanese Knotweed Rhizome Bark Extract as Determined by Antioxidant Activity-Guided Fractionation
title_full (−)-Epicatechin—An Important Contributor to the Antioxidant Activity of Japanese Knotweed Rhizome Bark Extract as Determined by Antioxidant Activity-Guided Fractionation
title_fullStr (−)-Epicatechin—An Important Contributor to the Antioxidant Activity of Japanese Knotweed Rhizome Bark Extract as Determined by Antioxidant Activity-Guided Fractionation
title_full_unstemmed (−)-Epicatechin—An Important Contributor to the Antioxidant Activity of Japanese Knotweed Rhizome Bark Extract as Determined by Antioxidant Activity-Guided Fractionation
title_short (−)-Epicatechin—An Important Contributor to the Antioxidant Activity of Japanese Knotweed Rhizome Bark Extract as Determined by Antioxidant Activity-Guided Fractionation
title_sort (−)-epicatechin—an important contributor to the antioxidant activity of japanese knotweed rhizome bark extract as determined by antioxidant activity-guided fractionation
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7832395/
https://www.ncbi.nlm.nih.gov/pubmed/33477734
http://dx.doi.org/10.3390/antiox10010133
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