Insight into the Antioxidant Activity of 1,8-Dihydroxynaphthalene Allomelanin Nanoparticles
Melanins are stable and non-toxic pigments with great potential as chemopreventive agents against oxidative stress for medical and cosmetic applications. Allomelanin is a class of nitrogen-free melanin often found in fungi. The artificial allomelanin obtained by the polymerization of 1,8-dihydroxyna...
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| Format: | Article |
| Language: | English |
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MDPI AG
2023-07-01
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| Series: | Antioxidants |
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| Online Access: | https://www.mdpi.com/2076-3921/12/8/1511 |
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| author | Alexandra Mavridi-Printezi Fabio Mollica Rosa Lucernati Marco Montalti Riccardo Amorati |
| author_facet | Alexandra Mavridi-Printezi Fabio Mollica Rosa Lucernati Marco Montalti Riccardo Amorati |
| author_sort | Alexandra Mavridi-Printezi |
| collection | DOAJ |
| description | Melanins are stable and non-toxic pigments with great potential as chemopreventive agents against oxidative stress for medical and cosmetic applications. Allomelanin is a class of nitrogen-free melanin often found in fungi. The artificial allomelanin obtained by the polymerization of 1,8-dihydroxynaphthalene (DHN), poly-DHN (PDHN), has been recently indicated as a better radical quencher than polydopamine (PDA), a melanin model obtained by the polymerization of dopamine (DA); however, the chemical mechanisms underlying this difference are unclear. Here we investigate, by experimental and theoretical methods, the ability of PDHN nanoparticles (PDHN-NP), in comparison to PDA-NP, to trap alkylperoxyl (ROO<sup>•</sup>) and hydroperoxyl (HOO<sup>•</sup>) radicals that are involved in the propagation of peroxidation in real conditions. Our results demonstrate that PDHN-NP present a higher antioxidant efficiency with respect to PDA-NP against ROO<sup>•</sup> in water at pH 7.4 and against mixed ROO<sup>•</sup> and HOO<sup>•</sup> in acetonitrile, showing catalytic cross-termination activity. The antioxidant capacity of PDHN-NP in water is 0.8 mmol/g (ROO<sup>•</sup> radicals quenched by 1 g of PDHN-NP), with a rate constant of 3 × 10<sup>5</sup> M<sup>−1</sup> s<sup>−1</sup> for each reactive moiety. Quantum-mechanical calculations revealed that, thanks to the formation of a H-bond network, the quinones in PDHN-NP have a high affinity for H-atoms, thus justifying the high reactivity of PDHN-NP with HOO<sup>•</sup> observed experimentally. |
| first_indexed | 2024-03-11T00:10:11Z |
| format | Article |
| id | doaj.art-0fd4ac99a000487cb4f4af9125af66a5 |
| institution | Directory Open Access Journal |
| issn | 2076-3921 |
| language | English |
| last_indexed | 2024-03-11T00:10:11Z |
| publishDate | 2023-07-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Antioxidants |
| spelling | doaj.art-0fd4ac99a000487cb4f4af9125af66a52023-11-19T00:00:56ZengMDPI AGAntioxidants2076-39212023-07-01128151110.3390/antiox12081511Insight into the Antioxidant Activity of 1,8-Dihydroxynaphthalene Allomelanin NanoparticlesAlexandra Mavridi-Printezi0Fabio Mollica1Rosa Lucernati2Marco Montalti3Riccardo Amorati4Department of Chemistry “Giacomo Ciamician”, University of Bologna, Via Selmi 2, 40126 Bologna, ItalyDepartment of Chemistry “Giacomo Ciamician”, University of Bologna, Via Selmi 2, 40126 Bologna, ItalyDepartment of Chemistry “Giacomo Ciamician”, University of Bologna, Via Selmi 2, 40126 Bologna, ItalyDepartment of Chemistry “Giacomo Ciamician”, University of Bologna, Via Selmi 2, 40126 Bologna, ItalyDepartment of Chemistry “Giacomo Ciamician”, University of Bologna, Via Selmi 2, 40126 Bologna, ItalyMelanins are stable and non-toxic pigments with great potential as chemopreventive agents against oxidative stress for medical and cosmetic applications. Allomelanin is a class of nitrogen-free melanin often found in fungi. The artificial allomelanin obtained by the polymerization of 1,8-dihydroxynaphthalene (DHN), poly-DHN (PDHN), has been recently indicated as a better radical quencher than polydopamine (PDA), a melanin model obtained by the polymerization of dopamine (DA); however, the chemical mechanisms underlying this difference are unclear. Here we investigate, by experimental and theoretical methods, the ability of PDHN nanoparticles (PDHN-NP), in comparison to PDA-NP, to trap alkylperoxyl (ROO<sup>•</sup>) and hydroperoxyl (HOO<sup>•</sup>) radicals that are involved in the propagation of peroxidation in real conditions. Our results demonstrate that PDHN-NP present a higher antioxidant efficiency with respect to PDA-NP against ROO<sup>•</sup> in water at pH 7.4 and against mixed ROO<sup>•</sup> and HOO<sup>•</sup> in acetonitrile, showing catalytic cross-termination activity. The antioxidant capacity of PDHN-NP in water is 0.8 mmol/g (ROO<sup>•</sup> radicals quenched by 1 g of PDHN-NP), with a rate constant of 3 × 10<sup>5</sup> M<sup>−1</sup> s<sup>−1</sup> for each reactive moiety. Quantum-mechanical calculations revealed that, thanks to the formation of a H-bond network, the quinones in PDHN-NP have a high affinity for H-atoms, thus justifying the high reactivity of PDHN-NP with HOO<sup>•</sup> observed experimentally.https://www.mdpi.com/2076-3921/12/8/1511antioxidantsnanoparticlesmelaninallomelaninpolydopamineROS |
| spellingShingle | Alexandra Mavridi-Printezi Fabio Mollica Rosa Lucernati Marco Montalti Riccardo Amorati Insight into the Antioxidant Activity of 1,8-Dihydroxynaphthalene Allomelanin Nanoparticles Antioxidants antioxidants nanoparticles melanin allomelanin polydopamine ROS |
| title | Insight into the Antioxidant Activity of 1,8-Dihydroxynaphthalene Allomelanin Nanoparticles |
| title_full | Insight into the Antioxidant Activity of 1,8-Dihydroxynaphthalene Allomelanin Nanoparticles |
| title_fullStr | Insight into the Antioxidant Activity of 1,8-Dihydroxynaphthalene Allomelanin Nanoparticles |
| title_full_unstemmed | Insight into the Antioxidant Activity of 1,8-Dihydroxynaphthalene Allomelanin Nanoparticles |
| title_short | Insight into the Antioxidant Activity of 1,8-Dihydroxynaphthalene Allomelanin Nanoparticles |
| title_sort | insight into the antioxidant activity of 1 8 dihydroxynaphthalene allomelanin nanoparticles |
| topic | antioxidants nanoparticles melanin allomelanin polydopamine ROS |
| url | https://www.mdpi.com/2076-3921/12/8/1511 |
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