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Enhanced Antioxidant Activity under Biomimetic Settings of Ascorbic Acid Included in Halloysite Nanotubes

Antioxidant activity of native vitamin C (ascorbic acid, AH(2)) is hampered by instability in solution. Selective loading of AH(2) into the inner lumen of natural halloysite nanotubes (HNT) yields a composite nanoantioxidant (HNT/AH(2)), which was characterized and investigated for its reactivity wi...

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Autores principales: Baschieri, Andrea, Amorati, Riccardo, Benelli, Tiziana, Mazzocchetti, Laura, D’Angelo, Emanuele, Valgimigli, Luca
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2019
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6406349/
https://www.ncbi.nlm.nih.gov/pubmed/30691231
http://dx.doi.org/10.3390/antiox8020030
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author Baschieri, Andrea
Amorati, Riccardo
Benelli, Tiziana
Mazzocchetti, Laura
D’Angelo, Emanuele
Valgimigli, Luca
author_facet Baschieri, Andrea
Amorati, Riccardo
Benelli, Tiziana
Mazzocchetti, Laura
D’Angelo, Emanuele
Valgimigli, Luca
author_sort Baschieri, Andrea
collection PubMed
description Antioxidant activity of native vitamin C (ascorbic acid, AH(2)) is hampered by instability in solution. Selective loading of AH(2) into the inner lumen of natural halloysite nanotubes (HNT) yields a composite nanoantioxidant (HNT/AH(2)), which was characterized and investigated for its reactivity with the persistent 1,1-diphenyl-2-picrylhydrazyl (DPPH•) radical and with transient peroxyl radicals in the inhibited autoxidation of organic substrates, both in organic solution (acetonitrile) and in buffered (pH 7.4) water in comparison with native AH(2). HNT/AH(2) showed excellent antioxidant performance being more effective than native ascorbic acid by 131% in acetonitrile and 290% (three-fold) in aqueous solution, under identical settings. Reaction with peroxyl radicals has a rate constant of 1.4 × 10(6) M(−1) s(−1) and 5.1 × 10(4) M(−1) s(−1), respectively, in buffered water (pH 7.4) and acetonitrile, at 30 °C. Results offer physical understanding of the factors governing HNT/AH(2) reactivity. Improved performance of HNT/AH(2) is unprecedented among forms of stabilized ascorbic acid and its relevance is discussed on kinetic grounds.
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spelling pubmed-64063492019-03-08 Enhanced Antioxidant Activity under Biomimetic Settings of Ascorbic Acid Included in Halloysite Nanotubes Baschieri, Andrea Amorati, Riccardo Benelli, Tiziana Mazzocchetti, Laura D’Angelo, Emanuele Valgimigli, Luca Antioxidants (Basel) Article Antioxidant activity of native vitamin C (ascorbic acid, AH(2)) is hampered by instability in solution. Selective loading of AH(2) into the inner lumen of natural halloysite nanotubes (HNT) yields a composite nanoantioxidant (HNT/AH(2)), which was characterized and investigated for its reactivity with the persistent 1,1-diphenyl-2-picrylhydrazyl (DPPH•) radical and with transient peroxyl radicals in the inhibited autoxidation of organic substrates, both in organic solution (acetonitrile) and in buffered (pH 7.4) water in comparison with native AH(2). HNT/AH(2) showed excellent antioxidant performance being more effective than native ascorbic acid by 131% in acetonitrile and 290% (three-fold) in aqueous solution, under identical settings. Reaction with peroxyl radicals has a rate constant of 1.4 × 10(6) M(−1) s(−1) and 5.1 × 10(4) M(−1) s(−1), respectively, in buffered water (pH 7.4) and acetonitrile, at 30 °C. Results offer physical understanding of the factors governing HNT/AH(2) reactivity. Improved performance of HNT/AH(2) is unprecedented among forms of stabilized ascorbic acid and its relevance is discussed on kinetic grounds. MDPI 2019-01-27 /pmc/articles/PMC6406349/ /pubmed/30691231 http://dx.doi.org/10.3390/antiox8020030 Text en © 2019 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
Baschieri, Andrea
Amorati, Riccardo
Benelli, Tiziana
Mazzocchetti, Laura
D’Angelo, Emanuele
Valgimigli, Luca
Enhanced Antioxidant Activity under Biomimetic Settings of Ascorbic Acid Included in Halloysite Nanotubes
title Enhanced Antioxidant Activity under Biomimetic Settings of Ascorbic Acid Included in Halloysite Nanotubes
title_full Enhanced Antioxidant Activity under Biomimetic Settings of Ascorbic Acid Included in Halloysite Nanotubes
title_fullStr Enhanced Antioxidant Activity under Biomimetic Settings of Ascorbic Acid Included in Halloysite Nanotubes
title_full_unstemmed Enhanced Antioxidant Activity under Biomimetic Settings of Ascorbic Acid Included in Halloysite Nanotubes
title_short Enhanced Antioxidant Activity under Biomimetic Settings of Ascorbic Acid Included in Halloysite Nanotubes
title_sort enhanced antioxidant activity under biomimetic settings of ascorbic acid included in halloysite nanotubes
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6406349/
https://www.ncbi.nlm.nih.gov/pubmed/30691231
http://dx.doi.org/10.3390/antiox8020030
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