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A special issue of Antioxidants (ISSN 2076-3921).

Deadline for manuscript submissions: closed (31 August 2021) | Viewed by 48793

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Dr. Riccardo Amorati

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Department of Chemistry “G. Ciamician”, University of Bologna, Via Gobetti 83, 40129 Bologna, Italy
Interests: nanoantioxidants; methods to measure antioxidant activity; mechanistic aspects of antioxidant activity; computational chemistry; kinetics of radical reactions
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Dr. Andrea Baschieri

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Department of Physical and Chemical Sciences, Università degli Studi dell’Aquila, via Vetoio, 67100 L’Aquila, Italy
Interests: free radicals; antioxidant activity; natural antioxidants; nano-structured antioxidant materials; nitroxyl radicals; catalysis

Special Issue Information

Dear Colleagues,

The Feynman quote “There's Plenty of Room at the Bottom” inspired the development of nanotechnology by suggesting that many structures of the macroscopic world could be reproduced at a micro- or even nanoscale. At the same time, the increased ability to manipulate matter at the nanoscale has allowed scientists to develop nano-sized material that could behave as though they mimic natural molecules. The potential of these ideas applied to the field of antioxidant research is clear. Recently, the term “nanoantioxidant” has been created to indicate nano-sized materials having antioxidant activity. This very broad term includes nanomaterials having intrinsic radical trapping ability or SOD – CAT – GPx enzyme-like activities, inert scaffolds covalently linked to small-molecular or macromolecular antioxidants, nanosized crystals of sparingly soluble antioxidants, nanocarriers or hybrid systems. These materials have potentially many advantages but, like all new technologies, they require to be known in detail to avoid pitfalls. With this Special Issue, we aim at increasing the knowledge about nanoantioxidants, and we propose to contributors the following list of research themes. This list is not exhaustive.

1) new materials with antioxidant activity

2) chemical or cell-based methods for measuring the antioxidant activity of nanomaterials

3) chemical studies of mechanisms of radical trapping by nanoantioxidants

4) nanocarriers or nanocapsules for targeted transport and controlled release of antioxidants

5) preparation and activity of antioxidant nanocrystals

6) biological activity and toxicology of nanoantioxidants

Dr. Riccardo Amorati
Dr. Andrea Baschieri
Guest Editors

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Published Papers (10 papers)

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Research

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13 pages, 3011 KiB

Open AccessArticle

Chain-Breaking Antioxidant and Peroxyl Radical Trapping Activity of Phenol-Coated Magnetic Iron Oxide Nanoparticles

by Stefano Scurti, Daniele Caretti, Fabio Mollica, Erika Di Antonio and Riccardo Amorati

Antioxidants 2022, 11(6), 1163; https://doi.org/10.3390/antiox11061163 - 14 Jun 2022

Cited by 4 | Viewed by 2650

Abstract

Superparamagnetic iron oxide nanoparticles (SPION) are important materials for biomedical applications, and phenol capping is a common procedure to passivate their surface. As phenol capped SPION have been reported to behave as antioxidants, herein, we investigate the mechanism underlying this activity by studying the reaction with alkyl peroxyl (ROO^•) radicals. SPION were prepared by coprecipitation of Fe(II) and Fe(III), using phenolic antioxidants (gallic acid, Trolox and nordihydroguaiaretic acid) as post-synthesis capping agents and by different purification procedures. The reactivity of ROO^• was investigated by inhibited autoxidation studies, using styrene as an oxidizable substrate (solvent MeCN, 30 °C) and azo-bis(isobutyronitrile) as a radical initiator. While unprotected, bare SPION behaved as prooxidant, accelerating the O₂ consumption of styrene autoxidation, phenol capping provided a variable antioxidant effect that was dependent upon the purification degree of the material. Thoroughly washed SPION, containing from 7% to 14% (w/w) of phenols, had a low reactivity toward peroxyl radicals, while SPION with a higher phenol content (46% to 55%) showed a strong radical trapping activity. Our results indicate that the antioxidant activity of phenol-capped SPION can be caused by its release in a solution of weakly bound phenols, and that purification plays a major role in determining the properties of these materials. Full article

(This article belongs to the Special Issue Nanoantioxidants)

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20 pages, 4040 KiB

Open AccessArticle

Vitamin E Delivery Systems Increase Resistance to Oxidative Stress in Red Deer Sperm Cells: Hydrogel and Nanoemulsion Carriers

by Alejandro Jurado-Campos, Pedro Javier Soria-Meneses, Francisca Sánchez-Rubio, Enrique Niza, Iván Bravo, Carlos Alonso-Moreno, María Arenas-Moreira, Olga García-Álvarez, Ana Josefa Soler, José Julián Garde and María del Rocío Fernández-Santos

Antioxidants 2021, 10(11), 1780; https://doi.org/10.3390/antiox10111780 - 6 Nov 2021

Cited by 14 | Viewed by 3983

Abstract

Oxidative stress has become a major concern in the field of spermatology, and one of the possible solutions to this acute problem would be the use of antioxidant protection; however, more studies are required in this field, as highly contradictory results regarding the addition of antioxidants have been obtained. Vitamin E is a powerful biological antioxidant, but its low stability and high hydrophobicity limit its application in spermatology, making the use of organic solvents necessary, which renders spermatozoa practically motionless. Keeping this in mind, we propose the use of hydrogels (HVEs) and nanoemulsions (NVEs), alone or in combination, as carriers for the controlled release of vitamin E, thus, improving its solubility and stability and preventing oxidative stress in sperm cells. Cryopreserved sperm from six stags was thawed and extended to 30 × 10⁶ sperm/mL in Bovine Gamete Medium (BGM). Once aliquoted, the samples were incubated as follows: control, free vitamin E (1 mM), NVEs (9 mM), HVEs (1 mM), and the combination of HVEs and NVEs (H + N), with or without induced oxidative stress (100 µM Fe²⁺/ascorbate). The different treatments were analyzed after 0, 2, 5, and 24 h of incubation at 37 °C. Motility (CASA^®), viability (YO-PRO-1/IP), mitochondrial membrane potential (Mitotracker Deep Red 633), lipid peroxidation (C₁₁ BODIPY 581/591), intracellular reactive oxygen species production (CM-H₂DCFDA), and DNA status (SCSA^®) were assessed. Our results show that the deleterious effects of exogenous oxidative stress were prevented by the vitamin E-loaded carriers proposed, while the kinematic sperm parameters (p ˂ 0.05) and sperm viability were always preserved. Moreover, the vitamin E formulations maintained and preserved mitochondrial activity, prevented sperm lipid peroxidation, and decreased reactive oxygen species (ROS) production (p ˂ 0.05) under oxidative stress conditions. Vitamin E formulations were significantly different as regards the free vitamin E samples (p < 0.001), whose sperm kinematic parameters drastically decreased. This is the first time that vitamin E has been formulated as hydrogels. This new formulation could be highly relevant for sperm physiology preservation, signifying an excellent approach against sperm oxidative damage. Full article

(This article belongs to the Special Issue Nanoantioxidants)

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17 pages, 3971 KiB

Open AccessArticle

Oleanolic Acid Nanofibers Attenuated Particulate Matter-Induced Oxidative Stress in Keratinocytes

by Hsuan Fu, Feng-Lin Yen, Pao-Hsien Huang, Chun-Yin Yang and Chia-Hung Yen

Antioxidants 2021, 10(9), 1411; https://doi.org/10.3390/antiox10091411 - 2 Sep 2021

Cited by 8 | Viewed by 3134

Abstract

Airborne particulate matter (PM) is one of the indicators of air pollution, and it is also the main factor causing oxidative stress in the skin. Oleanolic acid (OA), a natural terpenoid compound, effectively inhibited PM-induced skin aging; however, OA has poor water solubility and skin absorption, which limit its application in medicines and cosmetics. The aim of this study was to prepare oleanolic acid nanofibers (OAnf) and evaluate the effects of OA and OAnf in PM-treated keratinocytes. The results showed that OA dissolved in dissolved in dimethyl sulfoxide (DMSO) attenuated PM-induced reactive oxygen species overproduction, stress-activated protein kinase/Jun-amino-terminal kinase (SAPK/JNK) activation, and the expressions of inflammatory and skin-aging-related proteins. In addition, the nanofiber process of OA effectively improved the water solubility of OA more than 99,000-fold through changing its physicochemical properties, including a surface area increase, particle size reduction, amorphous transformation, and hydrogen bonding formation with excipients. The skin penetration ability of OAnf was consistently over 10-fold higher than that of OA. Moreover, when dissolved in PBS, OAnf displayed superior antioxidant, anti-inflammatory, and anti-skin aging activities in PM-treated keratinocytes than OA. In conclusion, our findings suggest that OAnf could be a topical antioxidant formulation to attenuate skin problems caused by PM. Full article

(This article belongs to the Special Issue Nanoantioxidants)

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18 pages, 2737 KiB

Open AccessArticle

Micellar Nanocarriers of Hydroxytyrosol Are Protective against Parkinson’s Related Oxidative Stress in an In Vitro hCMEC/D3-SH-SY5Y Co-Culture System

by Leah Mursaleen, Brendon Noble, Satyanarayana Somavarapu and Mohammed Gulrez Zariwala

Antioxidants 2021, 10(6), 887; https://doi.org/10.3390/antiox10060887 - 31 May 2021

Cited by 14 | Viewed by 3985

Abstract

Hydroxytyrosol (HT) is a natural phenolic antioxidant which has neuroprotective effects in models of Parkinson’s disease (PD). Due to issues such as rapid metabolism, HT is unlikely to reach the brain at therapeutic concentrations required for a clinical effect. We have previously developed micellar nanocarriers from Pluronic F68^® (P68) and dequalinium (DQA) which have suitable characteristics for brain delivery of antioxidants and iron chelators. The aim of this study was to utilise the P68 + DQA nanocarriers for HT alone, or in combination with the iron chelator deferoxamine (DFO), and assess their physical characteristics and ability to pass the blood–brain barrier and protect against rotenone in a cellular hCMEC/D3-SH-SY5Y co-culture system. Both HT and HT + DFO formulations were less than 170 nm in size and demonstrated high encapsulation efficiencies (up to 97%). P68 + DQA nanoformulation enhanced the mean blood–brain barrier (BBB) passage of HT by 50% (p < 0.0001, n = 6). This resulted in increased protection against rotenone induced cytotoxicity and oxidative stress by up to 12% and 9%, respectively, compared to the corresponding free drug treatments (p < 0.01, n = 6). This study demonstrates for the first time the incorporation of HT and HT + DFO into P68 + DQA nanocarriers and successful delivery of these nanocarriers across a BBB model to protect against PD-related oxidative stress. These nanocarriers warrant further investigation to evaluate whether this enhanced neuroprotection is exhibited in in vivo PD models. Full article

(This article belongs to the Special Issue Nanoantioxidants)

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17 pages, 3008 KiB

Open AccessArticle

Protective Effects of Liposomal Curcumin on Oxidative Stress/Antioxidant Imbalance, Metalloproteinases 2 and -9, Histological Changes and Renal Function in Experimental Nephrotoxicity Induced by Gentamicin

by Adriana Elena Bulboacă, Alina Porfire, Sorana D. Bolboacă, Cristina Ariadna Nicula, Dana Gabriela Feștilă, Alexandra Roman, Ruxandra Mioara Râjnoveanu, Armand Râjnoveanu, Gabriela Dogaru, Paul-Mihai Boarescu, Vasile Rus, Corneliu Angelo Bulboacă, Alexandra Ina Bulboacă and Ioana Stănescu

Antioxidants 2021, 10(2), 325; https://doi.org/10.3390/antiox10020325 - 22 Feb 2021

Cited by 16 | Viewed by 3333

Abstract

Background: Our study aimed to assess the efficiency of Curcumin nanoformulation (LCC) on experimental nephrotoxicity induced by Gentamicin in rats. Methods: Six groups of seven rats were used: C—(control group) received saline solution i.p. (i.p. = intraperitoneal), G—gentamicin (G, 80 mg/kg body weight (b.w.)), GCC1 and GCC2—with G and CC solution (single dose of 10 mg/kg b.w.-CC1, or 20 mg/kg b.w.-CC2), GLCC1 (10 mg/kg b.w.) and GLCC2 (20 mg/kg b.w.) with G and LCC administration. Oxidative stress parameters (NOx = nitric oxide, MDA = malondialdehyde, TOS = total oxidative stress), antioxidant parameters (CAT = catalase, TAC = total antioxidant capacity), matrix metalloproteinases (MMP-2 and MMP-9), and renal function parameters (creatinine, blood urea nitrogen, and urea) were measured. Kidneys histopathologic examination was made for each group. Results: Pretreatment with CC and LCC in both doses had significantly alleviating effects on assessed parameters (NOx, MDA, TOS, CAT, TAC, MMP-2, and -9) as compared with the untreated group (p < 0.006). Histopathological aspect and renal function were significantly improved in CC and LCC groups. Liposomal formulation (LCC) showed higher efficiency on all examined parameters compared to CC (p < 0.006). Conclusions: Our results demonstrated improving renal function and kidney cytoarchitecture, oxidative stress/antioxidant/balance, and MMPs plasma concentrations with better dose-related efficacity of LCC than CC. Full article

(This article belongs to the Special Issue Nanoantioxidants)

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21 pages, 4710 KiB

Open AccessArticle

Mesoporous Polydopamine Nanoparticles Attenuate Morphine Tolerance in Neuropathic Pain Rats by Inhibition of Oxidative Stress and Restoration of the Endogenous Antioxidant System

by Yaswanth Kuthati, Prabhakar Busa, Srikrishna Tummala, Vaikar Navakanth Rao, Venkata Naga Goutham Davuluri, Yen-Peng Ho and Chih-Shung Wong

Antioxidants 2021, 10(2), 195; https://doi.org/10.3390/antiox10020195 - 29 Jan 2021

Cited by 27 | Viewed by 4813

Abstract

Oxidative stress resulting from reactive oxygen species (ROS) is known to play a key role in numerous neurological disorders, including neuropathic pain. Morphine is one of the commonly used opioids for pain management. However, long-term administration of morphine results in morphine antinociceptive tolerance (MAT) through elevation of ROS and suppression of natural antioxidant defense mechanisms. Recently, mesoporous polydopamine (MPDA) nanoparticles (NPS) have been known to possess strong antioxidant properties. We speculated that morphine delivery through an antioxidant nanocarrier might be a reasonable strategy to alleviate MAT. MPDAs showed a high drug loading efficiency of ∼50%, which was much higher than conventional NPS. Spectral and in vitro studies suggest a superior ROS scavenging ability of NPS. Results from a rat neuropathic pain model demonstrate that MPDA-loaded morphine (MPDA@Mor) is efficient in minimizing MAT with prolonged analgesic effect and suppression of pro-inflammatory cytokines. Additionally, serum levels of liver enzymes and levels of endogenous antioxidants were measured in the liver. Treatment with free morphine resulted in elevated levels of liver enzymes and significantly lowered the activities of endogenous antioxidant enzymes in comparison with the control and MPDA@Mor-treated group. Histopathological examination of the liver revealed that MPDA@Mor can significantly reduce the hepatotoxic effects of morphine. Taken together, our current work will provide an important insight into the development of safe and effective nano-antioxidant platforms for neuropathic pain management. Full article

(This article belongs to the Special Issue Nanoantioxidants)

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23 pages, 5658 KiB

Open AccessArticle

Phytogenic Fabrication of Ag–Fe Bimetallic Nanoparticles for Cell Cycle Arrest and Apoptosis Signaling Pathways in Candida auris by Generating Oxidative Stress

by Majid Rasool Kamli, Vartika Srivastava, Nahid H. Hajrah, Jamal S. M. Sabir, Arif Ali, Maqsood Ahmad Malik and Aijaz Ahmad

Antioxidants 2021, 10(2), 182; https://doi.org/10.3390/antiox10020182 - 27 Jan 2021

Cited by 27 | Viewed by 4065

Abstract

Novel green synthetic nanomedicines have been recognized as alternative therapies with the potential to be antifungal agents. Apoptosis induction, cell cycle arrest and activation of the antioxidant defense system in fungal cells have also gained attention as emerging drug targets. In this study, a facile and biodegradable synthetic route was developed to prepare Ag–Fe bimetallic nanoparticles using aqueous extract of Beta vulgaris L. Surface plasmon resonance of Beta vulgaris-assisted AgNPs nanoparticles was not observed in the UV-visible region of Ag–Fe bimetallic NPs, which confirms the formation of Ag–Fe nanoparticles. Beta vulgaris-assisted Ag–Fe NPs were characterized by FTIR spectroscopy, scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction and TGA-DTG analysis for their structural and morphological properties. The as-prepared Ag–Fe NPs were well dispersed and spherical with the average particle size of 15 nm. The antifungal activity of these Ag–Fe NPs against clinical isolates of Candida auris was determined by broth microdilution and cell viability assays. For insights into mechanisms, induction of apoptosis and triggering cell cycle arrest were studied following standard protocols. Furthermore, analysis of antioxidant defense enzymes was determined spectrophotometrically. Antifungal susceptibility results revealed high antifungal activity with MIC values ranging from 0.19 to 0.39 µg/mL. Further studies showed that Ag–Fe NPs were able to induce apoptosis, cell cycle arrest in G2/M phase and disturbances in primary and secondary antioxidant enzymes. This study presents the potential of Ag–Fe NPs to inhibit and potentially eradicate C. auris by inducing apoptosis, cell cycle arrest and increased levels of oxidative stress. Full article

(This article belongs to the Special Issue Nanoantioxidants)

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17 pages, 22400 KiB

Open AccessArticle

Antioxidant Carbon Nanoparticles Inhibit Fibroblast-Like Synoviocyte Invasiveness and Reduce Disease Severity in a Rat Model of Rheumatoid Arthritis

by Mark R. Tanner, Redwan Huq, William K. A. Sikkema, Lizanne G. Nilewski, Nejla Yosef, Cody Schmitt, Carlos P. Flores-Suarez, Arielle Raugh, Teresina Laragione, Pércio S. Gulko, James M. Tour and Christine Beeton

Antioxidants 2020, 9(10), 1005; https://doi.org/10.3390/antiox9101005 - 16 Oct 2020

Cited by 3 | Viewed by 3127

Abstract

Reactive oxygen species have been involved in the pathogenesis of rheumatoid arthritis (RA). Our goal was to determine the effects of selectively scavenging superoxide (O₂^•−) and hydroxyl radicals with antioxidant nanoparticles, called poly(ethylene glycol)-functionalized hydrophilic carbon clusters (PEG-HCCs), on the pathogenic functions of fibroblast-like synoviocytes (FLS) from patients with rheumatoid arthritis (RA) and on the progression of an animal model of RA. We used human FLS from patients with RA to determine PEG-HCC internalization and effects on FLS cytotoxicity, invasiveness, proliferation, and production of proteases. We used the pristane-induced arthritis (PIA) rat model of RA to assess the benefits of PEG-HCCs on reducing disease severity. PEG-HCCs were internalized by RA-FLS, reduced their intracellular O₂^•−, and reduced multiple measures of their pathogenicity in vitro, including proliferation and invasion. In PIA, PEG-HCCs caused a 65% reduction in disease severity, as measured by a standardized scoring system of paw inflammation and caused a significant reduction in bone and tissue damage, and circulating rheumatoid factor. PEG-HCCs did not induce lymphopenia during PIA. Our study demonstrated a role for O₂^•− and hydroxyl radicals in the pathogenesis of a rat model of RA and showed efficacy of PEG-HCCs in treating a rat model of RA. Full article

(This article belongs to the Special Issue Nanoantioxidants)

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Review

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21 pages, 5023 KiB

Open AccessReview

Methods to Determine Chain-Breaking Antioxidant Activity of Nanomaterials beyond DPPH^•. A Review

by Andrea Baschieri and Riccardo Amorati

Antioxidants 2021, 10(10), 1551; https://doi.org/10.3390/antiox10101551 - 29 Sep 2021

Cited by 45 | Viewed by 7960

Abstract

This review highlights the progress made in recent years in understanding the mechanism of action of nanomaterials with antioxidant activity and in the chemical methods used to evaluate their activity. Nanomaterials represent one of the most recent frontiers in the research for improved antioxidants, but further development is hampered by a poor characterization of the ‘‘antioxidant activity’’ property and by using oversimplified chemical methods. Inhibited autoxidation experiments provide valuable information about the interaction with the most important radicals involved in the lipid oxidation, namely alkylperoxyl and hydroperoxyl radicals, and demonstrate unambiguously the ability to stop the oxidation of organic materials. It is proposed that autoxidation methods should always complement (and possibly replace) the use of assays based on the quenching of stable radicals (such as DPPH^• and ABTS^•+). The mechanisms leading to the inhibition of the autoxidation (sacrificial and catalytic radical trapping antioxidant activity) are described in the context of nanoantioxidants. Guidelines for the selection of the appropriate testing conditions and of meaningful kinetic analysis are also given. Full article

(This article belongs to the Special Issue Nanoantioxidants)

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19 pages, 2471 KiB

Open AccessReview

Nano-Structured Lignin as Green Antioxidant and UV Shielding Ingredient for Sunscreen Applications

by Davide Piccinino, Eliana Capecchi, Elisabetta Tomaino, Sofia Gabellone, Valeria Gigli, Daniele Avitabile and Raffaele Saladino

Antioxidants 2021, 10(2), 274; https://doi.org/10.3390/antiox10020274 - 10 Feb 2021

Cited by 104 | Viewed by 9354

Abstract

Green, biocompatible, and biodegradable antioxidants represent a milestone in cosmetic and cosmeceutical applications. Lignin is the most abundant polyphenol in nature, recovered as a low-cost waste from the pulp and paper industry and biorefinery. This polymer is characterized by beneficial physical and chemical properties which are improved at the nanoscale level due to the emergence of antioxidant and UV shielding activities. Here we review the use of lignin nanoparticles in cosmetic and cosmeceutical applications, focusing on sunscreen and antiaging formulations. Advances in the technology for the preparation of lignin nanoparticles are described highlighting structure activity relationships. Full article

(This article belongs to the Special Issue Nanoantioxidants)

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