Special Issue "Feature Papers in Antioxidants in 2018"

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

Deadline for manuscript submissions: closed (30 April 2018)

Special Issue Editor

Guest Editor
Prof. Dr. Stanley Omaye

Department of Agriculture, Nutrition and Veterinary Sciences, University of Nevada, 1664 North Virginia Street, Reno, NV 89557, USA
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Interests: involved in various research regarding nutrition, toxicology, and environmental-health sciences; research has been directed toward better understanding the role of micronutrients, antioxidants, and other bioactive chemicals in health, and developing effective pharmacological and nutritional interventions in chronic diseases and aging; interested in the health effects of environmental or occupational substances, such as, arsenic, mercury, air pollutants, and products of nanotechnology

Special Issue Information

Dear Colleagues,

This is a Special Issue of high quality papers in Open Access form by the editorial board members, or those invited by the editorial office and the Editor-in-Chief. Authors can submit their manuscripts through the Manuscript Tracking System at http://susy.mdpi.com/user/manuscripts/upload?journal=antioxidants. Manuscripts are published upon acceptance, regardless of the Special Issue publication date.

Prof. Dr. Stanley Omaye
Guest Editor

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Published Papers (8 papers)

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Research

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Open AccessArticle Cytoprotective Activities of Milk Thistle Seed Oil Used in Traditional Tunisian Medicine on 7-Ketocholesterol and 24S-Hydroxycholesterol-Induced Toxicity on 158N Murine Oligodendrocytes
Antioxidants 2018, 7(7), 95; https://doi.org/10.3390/antiox7070095
Received: 11 June 2018 / Revised: 4 July 2018 / Accepted: 17 July 2018 / Published: 19 July 2018
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Abstract
The Asteraceae family is economically very important, because many of these plants are grown mainly for their food value, such as lettuce (Lactuca), chicory (Cichorium), and sunflower (Heliantus aminus). One of the typical properties of this family, which includes milk thistle (Sylibum
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The Asteraceae family is economically very important, because many of these plants are grown mainly for their food value, such as lettuce (Lactuca), chicory (Cichorium), and sunflower (Heliantus aminus). One of the typical properties of this family, which includes milk thistle (Sylibum marianum), is the richness of the oil in various compounds (flavonoids, alkaloids, tocopherols, and unsaturated fatty acids). Currently, and for the coming decades, age-related diseases, including neurodegenerative diseases, are a major public health problem. Preventing their appearance or opposing their evolution is a major objective. In this context, the cytoprotective activities of milk thistle seed oil produced in Tunisia were studied on the 158N model using 7-ketocholesterol (7KC) and 24S-hydroxycholesterol (24S) as cytotoxic agents. 7KC and 24S were used because they can be increased in the brain and body fluids of patients with major age-related neurodegenerative diseases, such as Alzheimer’s and Parkinson’s diseases. In order to evaluate the cytoprotective properties of milk thistle seed oil, complementary techniques of microscopy, flow cytometry, and biochemistry were used. The chemical composition of milk thistle seed oil has also been determined by various chromatography techniques. Milk thistle seed oils from different area of Tunisia are rich in tocopherols and are strongly antioxidant according to various biochemical tests (KRL (Kit Radicaux Libres), FRAP (Ferric Reducing Antioxidant Power), and DPPH (2,2-diphenyl-1-picrylhydrazyl)). The main fatty acids are linoleic acid (C18:2 n-6) and oleic acid (C18:1 n-9). The main polyphenols identified are homovanillic acid, p-coumaric acid, quercetin, and apigenin, with a predominance of vanillic acid. On 158N cells, milk thistle seed oil attenuates the cytotoxicity of 7KC and 24S including: loss of cell adhesion, increased plasma membrane permeability, mitochondrial dysfunction, overproduction of reactive oxygen species, induction of apoptosis, and autophagy. The attenuation of the cytotoxicity of 7KC and 24S observed with the milk thistle seed oil is in the order of that observed with α-tocopherol used as a positive control. In the presence of nigella seed oil, considered potentially cytotoxic, no cytoprotective effects were observed. Given the chemical characteristics, antioxidant properties, and cytoprotective activities of milk thistle seed oil, our results highlight the potential benefit of this oil for human health. Full article
(This article belongs to the Special Issue Feature Papers in Antioxidants in 2018)
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Open AccessArticle S-allylmercaptoglutathione Is a Substrate for Glutathione Reductase (E.C. 1.8.1.7) from Yeast (Saccharomyces cerevisiae)
Antioxidants 2018, 7(7), 86; https://doi.org/10.3390/antiox7070086
Received: 19 June 2018 / Revised: 28 June 2018 / Accepted: 4 July 2018 / Published: 6 July 2018
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Abstract
Allicin (diallylthiosulfinate) is a potent thiol reagent and natural defense substance produced by garlic (Allium sativum) tissues when damaged. Allicin acts as a redox toxin and oxidizes the cellular glutathione (GSH) pool producing S-allylmercaptoglutathione (GSSA). The cellular enzyme glutathione reductase
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Allicin (diallylthiosulfinate) is a potent thiol reagent and natural defense substance produced by garlic (Allium sativum) tissues when damaged. Allicin acts as a redox toxin and oxidizes the cellular glutathione (GSH) pool producing S-allylmercaptoglutathione (GSSA). The cellular enzyme glutathione reductase (GR) uses NADPH to reduce glutathione disulfide (GSSG) back to GSH and replenishes the GSH pool. It was not known whether GR could accept GSSA as a substrate. Here, we report that GR from yeast (Saccharomyces cerevisiae) shows Michaelis–Menten kinetics with GSSA as substrate in vitro (Km = 0.50 mM), but that GSSA is not as good a substrate as GSSG (Km = 0.07 mM). Furthermore, cells unable to synthesize GSH because the γ-glutamylcysteine synthetase (GSH1) gene is deleted, cannot grow without GSH supplementation and we show that the auxotrophic requirement for GSH in Δgsh1 mutants can be met by GSSA in the growth medium, suggesting that GSSA can be reduced to GSH in vivo. Full article
(This article belongs to the Special Issue Feature Papers in Antioxidants in 2018)
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Open AccessArticle Impact of Thermal Degradation of Cyanidin-3-O-Glucoside of Haskap Berry on Cytotoxicity of Hepatocellular Carcinoma HepG2 and Breast Cancer MDA-MB-231 Cells
Antioxidants 2018, 7(2), 24; https://doi.org/10.3390/antiox7020024
Received: 14 January 2018 / Revised: 24 January 2018 / Accepted: 25 January 2018 / Published: 27 January 2018
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Abstract
Cyanidin-3-O-glucoside (C3G), the predominant anthocyanin in haskap berries (Lonicera caerulea L.), possesses antioxidant and many other biological activities. This study investigated the impact of temperature and pH on the degradation of the C3G-rich haskap fraction. The effect of the thermal
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Cyanidin-3-O-glucoside (C3G), the predominant anthocyanin in haskap berries (Lonicera caerulea L.), possesses antioxidant and many other biological activities. This study investigated the impact of temperature and pH on the degradation of the C3G-rich haskap fraction. The effect of the thermal degradation products on the viability of hepatocellular carcinoma HepG2 and breast cancer MDA-MB-231 cells was also studied in vitro. Using column chromatography, the C3G-rich fraction was isolated from acetone extracts of haskap berries. The C3G stability in these fractions was studied under elevated temperatures (70 °C and 90 °C) at three different pH values (2.5, 4, and 7) by monitoring the concentration of C3G and its major degradation products, protocatechuic acid (PCA) and phloroglucinaldehyde (PGA), using liquid chromatography mass spectrometry. Significant degradation of C3G was observed at elevated temperatures and at neutral pH. Conversely, the PCA and PGA concentration increased at higher pH and temperature. Similar to C3G, neutral pH also has a prominent effect on the degradation of PGA, which is further accelerated by heating. The C3G-rich fraction exhibited dose-dependent inhibitory effects on cell metabolic activity when the HepG2 cells were exposed for 48 h. Interestingly, PGA but not PCA exhibited cytotoxic effects against both MDA-MB-231 and HepG2 cells. The results suggest that thermal food processing of haskap could influence its biological properties due to the degradation of C3G. Full article
(This article belongs to the Special Issue Feature Papers in Antioxidants in 2018)
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Open AccessArticle Polyphenolic Compounds Analysis of Old and New Apple Cultivars and Contribution of Polyphenolic Profile to the In Vitro Antioxidant Capacity
Antioxidants 2018, 7(1), 20; https://doi.org/10.3390/antiox7010020
Received: 6 December 2017 / Revised: 18 January 2018 / Accepted: 19 January 2018 / Published: 24 January 2018
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Abstract
Polyphenols are antioxidant ingredients in apples and are related to human health because of their free radical scavenging activities. The polyphenolic profiles of old and new apple cultivars (n = 15) were analysed using high-performance liquid chromatography (HPLC) with diode array detection
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Polyphenols are antioxidant ingredients in apples and are related to human health because of their free radical scavenging activities. The polyphenolic profiles of old and new apple cultivars (n = 15) were analysed using high-performance liquid chromatography (HPLC) with diode array detection (DAD). The in vitro antioxidant capacity was determined by total phenolic content (TPC) assay, hydrophilic trolox equivalent antioxidant capacity (H-TEAC) assay and hydrophilic oxygen radical absorbance (H-ORAC) assay. Twenty polyphenolic compounds were identified in all investigated apples by HPLC analysis. Quercetin glycosides (203 ± 108 mg/100 g) were the main polyphenols in the peel and phenolic acids (10 ± 5 mg/100 g) in the flesh. The calculated relative contribution of single compounds indicated flavonols (peel) and vitamin C (flesh) as the major contributors to the antioxidant capacity, in all cultivars investigated. The polyphenolic content (HPLC data) of the flesh differed significantly between old (29 ± 7 mg/100 g) and new (13 ± 4 mg/100 g) cultivars, and the antioxidant capacity of old apple cultivars was up to 30% stronger compared to new ones. Full article
(This article belongs to the Special Issue Feature Papers in Antioxidants in 2018)
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Review

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Open AccessReview Mitochondria-Targeted Antioxidants and Skeletal Muscle Function
Antioxidants 2018, 7(8), 107; https://doi.org/10.3390/antiox7080107
Received: 4 July 2018 / Revised: 6 August 2018 / Accepted: 7 August 2018 / Published: 8 August 2018
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Abstract
One of the main sources of reactive oxygen species (ROS) in skeletal muscle is the mitochondria. Prolonged or very high ROS exposure causes oxidative damage, which can be deleterious to muscle function, and as such, there is growing interest in targeting antioxidants to
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One of the main sources of reactive oxygen species (ROS) in skeletal muscle is the mitochondria. Prolonged or very high ROS exposure causes oxidative damage, which can be deleterious to muscle function, and as such, there is growing interest in targeting antioxidants to the mitochondria in an effort to prevent or treat muscle dysfunction and damage associated with disease and injury. Paradoxically, however, ROS also act as important signalling molecules in controlling cellular homeostasis, and therefore caution must be taken when supplementing with antioxidants. It is possible that mitochondria-targeted antioxidants may limit oxidative stress without suppressing ROS from non-mitochondrial sources that might be important for cell signalling. Therefore, in this review, we summarise literature relating to the effect of mitochondria-targeted antioxidants on skeletal muscle function. Overall, mitochondria-targeted antioxidants appear to exert beneficial effects on mitochondrial capacity and function, insulin sensitivity and age-related declines in muscle function. However, it seems that this is dependent on the type of mitochondrial-trageted antioxidant employed, and its specific mechanism of action, rather than simply targeting to the mitochondria. Full article
(This article belongs to the Special Issue Feature Papers in Antioxidants in 2018)
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Open AccessReview Cerium Oxide Nanoparticles: A Brief Review of Their Synthesis Methods and Biomedical Applications
Antioxidants 2018, 7(8), 97; https://doi.org/10.3390/antiox7080097
Received: 29 May 2018 / Revised: 12 July 2018 / Accepted: 19 July 2018 / Published: 24 July 2018
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Abstract
Cerium oxide nanoparticles (CeNPs) exhibit antioxidant properties both in vitro and in vivo. This is due to the self-regeneration of their surface, which is based on redox-cycling between 3+ and 4+ states for cerium, in response to their immediate environment. Additionally, oxygen vacancies
[...] Read more.
Cerium oxide nanoparticles (CeNPs) exhibit antioxidant properties both in vitro and in vivo. This is due to the self-regeneration of their surface, which is based on redox-cycling between 3+ and 4+ states for cerium, in response to their immediate environment. Additionally, oxygen vacancies in the lattice structure allow for alternating between CeO2 and CeO2−x during redox reactions. Research to identify and characterize the biomedical applications of CeNPs has been heavily focused on investigating their use in treating diseases that are characterized by higher levels of reactive oxygen species (ROS). Although the bio-mimetic activities of CeNPs have been extensively studied in vitro, in vivo interactions and associated protein corona formation are not well understood. This review describes: (1) the methods of synthesis for CeNPs, including the recent green synthesis methods that offer enhanced biocompatibility and a need for establishing a reference CeNP material for consistency across studies; (2) their enzyme-mimetic activities, with a focus on their antioxidant activities; and, (3) recent experimental evidence that demonstrates their ROS scavenging abilities and their potential use in personalized medicine. Full article
(This article belongs to the Special Issue Feature Papers in Antioxidants in 2018)
Open AccessReview Neopterin, Inflammation, and Oxidative Stress: What Could We Be Missing?
Antioxidants 2018, 7(7), 80; https://doi.org/10.3390/antiox7070080
Received: 12 April 2018 / Revised: 18 June 2018 / Accepted: 22 June 2018 / Published: 26 June 2018
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Abstract
Neopterin has been extensively used as a clinical marker of immune activation during inflammation in a wide range of conditions and stresses. However, the analysis of neopterin alone neglects the cellular reactions that generate it in response to interferon-γ. Neopterin is the oxidation
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Neopterin has been extensively used as a clinical marker of immune activation during inflammation in a wide range of conditions and stresses. However, the analysis of neopterin alone neglects the cellular reactions that generate it in response to interferon-γ. Neopterin is the oxidation product of 7,8-dihydroneopterin, which is a potent antioxidant generated by interferon-γ-activated macrophages. 7,8-Dihydroneopterin can protect macrophage cells from a range of oxidants through a scavenging reaction that generates either neopterin or dihydroxanthopterin, depending on the oxidant. Therefore, plasma and urinary neopterin levels are dependent on both macrophage activation to generate 7,8-dihydroneopterin and subsequent oxidation to neopterin. This relationship is clearly shown in studies of exercise and impact-induced injury during intense contact sport. Here, we argue that neopterin and total neopterin, which is the combined value of 7,8-dihydroneopterin and neopterin, could provide a more comprehensive analysis of clinical inflammation than neopterin alone. Full article
(This article belongs to the Special Issue Feature Papers in Antioxidants in 2018)
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Open AccessReview Betalains in Some Species of the Amaranthaceae Family: A Review
Antioxidants 2018, 7(4), 53; https://doi.org/10.3390/antiox7040053
Received: 6 February 2018 / Revised: 25 March 2018 / Accepted: 27 March 2018 / Published: 4 April 2018
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Abstract
Natural pigments are largely distributed in the plant kingdom. They belong to diverse groups, with distinct biochemical pathways. Betalains with colours that range from yellow to red-violet can de divided into two main subgroups: betaxanthins and betacyanins. These types of pigments are confined
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Natural pigments are largely distributed in the plant kingdom. They belong to diverse groups, with distinct biochemical pathways. Betalains with colours that range from yellow to red-violet can de divided into two main subgroups: betaxanthins and betacyanins. These types of pigments are confined into 13 families of the order Caryophyllales and in some genera of higher fungi (Amanita muscaria, Hygrocybe and Hygrophorus). The Amaranthaceae family includes diverse genera in which betalains are present: Alternanthera, Amaranthus, Beta, Chenopodium, Celosia and Gomphrena. The biosynthesis of betalains and their general biological properties were reviwed in the present work. In addition, the types of betalains present in some species of the aforementioned genera, their stability and production, as well as biological attributes, were reviewed. Full article
(This article belongs to the Special Issue Feature Papers in Antioxidants in 2018)
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