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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...
Autores principales: | , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
MDPI
2019
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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. |
format | Online Article Text |
id | pubmed-6406349 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2019 |
publisher | MDPI |
record_format | MEDLINE/PubMed |
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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