Special Issue "Free Radicals"

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

Deadline for manuscript submissions: closed (30 August 2013)

Special Issue Editor

Guest Editor
Prof. Dr. Isabel C. F. R. Ferreira (Website)

Mountain Research Center, School of Agriculture, Polytechnic Institute of Bragança, Campus de Santa Apolónia, apartado 1172, 5301-855 Bragança, Portugal
Interests: Chemistry of Natural Products: Extraction, identification, fractionation and isolation of chemical compounds in natural matrices; Nutraceuticals and functional foods: development of nutraceuticals and innovative food formulations with functional properties; Technology of Natural Products: Emerging technologies for conservation of food matrices

Special Issue Information

Dear Colleagues,

Contributions for this issue, both in form of original research and review articles, may cover all aspects related to free radicals belonging to oxygen, nitrogen or sulfur reactive species including methodologies of analysis that elucidate their production, cellular targets and mechanisms of action. Contributions related to antioxidant defences (enzymatic and non enzymatic) that act against free radicals are well come, as also the role of natural products or synthetic products in the help of endogenous antioxidant defence system. In this perspective, the antioxidants present on the diet assume a major importance and contributions describing analysis or isolation of phytochemicals or other bioactive compounds with antioxidant activity are interesting. The synthesis or use of synthetic compounds with activity towards free radicals is also of interest. Contributions reporting prooxidant role of free radicals and their potential benefits or adverse effects are well come, and finally studies describing relations between free radicals and medicine, ageing or food conservation, for example.

Dr. Isabel C. F. R. Ferreira
Guest Editor

Submission

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. Papers will be published continuously (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are refereed through a peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Antioxidants is an international peer-reviewed Open Access quarterly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 300 CHF (Swiss Francs). English correction and/or formatting fees of 250 CHF (Swiss Francs) will be charged in certain cases for those articles accepted for publication that require extensive additional formatting and/or English corrections.

Keywords

  • free radicals
  • reactive species
  • mechanisms
  • enzymatic/non-enzymatic defences
  • natural/synthetic antioxidants
  • prooxidants
  • applications
  • medicine
  • ageing

Published Papers (4 papers)

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Research

Open AccessArticle Free Radical Scavenging and Antioxidant Activities of Silymarin Components
Antioxidants 2013, 2(4), 398-407; doi:10.3390/antiox2040398
Received: 9 October 2013 / Revised: 13 November 2013 / Accepted: 21 November 2013 / Published: 10 December 2013
Cited by 10 | PDF Full-text (590 KB) | HTML Full-text | XML Full-text
Abstract
Silymarin is an over the counter food supplement that is sold as a liver enhancement and liver protection preparation. It is a major constituent of the seeds of Silybum marianum which is composed of a mixture of seven major components and several [...] Read more.
Silymarin is an over the counter food supplement that is sold as a liver enhancement and liver protection preparation. It is a major constituent of the seeds of Silybum marianum which is composed of a mixture of seven major components and several minor compounds. The seven major components: taxifolin, silychristin, silydianin, silybin A, silybin B, iso-silybin A and iso-silybin B were isolated and purified from the crude mixture of silymarin using preparative high performance liquid chromatography to determine which were the most effective for liver protection. Free radical scavenging, hydroxyl radical antioxidant capacity, oxygen radical antioxidant capacity, trolox-equivalent antioxidant capacity and total antioxidant capacity antioxidant activities were determined for each of the individual purified components as well as the crude silymarin mixture. Taxifolin was the most effective component for scavenging free radicals in the DPPH assay with an EC50 of 32 µM far more effective than all other components which showed EC50 ranging from 115 to 855 µM. Taxifolin was also found to be the most effective antioxidant in the oxygen radical antioxidant capacity (ORAC) assay with a trolox equivalent of 2.43 and the second most effective in the hydroxyl radical antioxidant capacity (HORAC) assay with a gallic acid equivalent of 0.57. Other antioxidants assays did not show significant differences between samples. Full article
(This article belongs to the Special Issue Free Radicals)
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Open AccessArticle Comparison of Antioxidant Properties of Refined and Whole Wheat Flour and Bread
Antioxidants 2013, 2(4), 370-383; doi:10.3390/antiox2040370
Received: 14 August 2013 / Revised: 13 November 2013 / Accepted: 14 November 2013 / Published: 26 November 2013
Cited by 5 | PDF Full-text (823 KB) | HTML Full-text | XML Full-text
Abstract
Antioxidant properties of refined and whole wheat flour and their resultant bread were investigated to document the effects of baking. Total phenolic content (TPC), 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity and oxygen radical absorbance capacity (ORAC) were employed to determine the content of [...] Read more.
Antioxidant properties of refined and whole wheat flour and their resultant bread were investigated to document the effects of baking. Total phenolic content (TPC), 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity and oxygen radical absorbance capacity (ORAC) were employed to determine the content of ethanol extractable phenolic compounds. HPLC was used to detect the presence of phenolic acids prior to their confirmation using LC-MS/MS. Whole wheat flour showed significantly higher antioxidant activity than refined flour (p < 0.05). There was a significant effect of the bread-making process with the TPC of whole wheat bread (1.50–1.65 mg/g) and white bread (0.79–1.03 mg/g) showing a respective reduction of 28% and 33% of the levels found in whole wheat and refined flour. Similarly, baking decreased DPPH radical scavenging capacity by 32% and 30%. ORAC values, however, indicated that baking increased the antioxidant activities of whole wheat and refined flour by 1.8 and 2.9 times, respectively. HPLC analysis showed an increase of 18% to 35% in ferulic acid after baking to obtain whole and refined wheat bread containing 330.1 and 25.3 µg/g (average), respectively. Whole wheat flour and bread were superior to refined flour and bread in in vitro antioxidant properties. Full article
(This article belongs to the Special Issue Free Radicals)
Open AccessArticle Valuing the Endangered Species Antirrhinum lopesianum: Neuroprotective Activities and Strategies for in vitro Plant Propagation
Antioxidants 2013, 2(4), 273-292; doi:10.3390/antiox2040273
Received: 15 August 2013 / Revised: 22 September 2013 / Accepted: 12 October 2013 / Published: 28 October 2013
Cited by 1 | PDF Full-text (2013 KB) | HTML Full-text | XML Full-text
Abstract
Plant phytochemicals are described as possessing considerable neuroprotective properties, due to radical scavenging capacity and acetylcholinesterase inhibitory activity, important bioactivities in neurodegeneration. Antirrhinum lopesianum is a rare endemism from the Iberian Peninsula, occurring at the northeastern border between Portugal and Spain. It [...] Read more.
Plant phytochemicals are described as possessing considerable neuroprotective properties, due to radical scavenging capacity and acetylcholinesterase inhibitory activity, important bioactivities in neurodegeneration. Antirrhinum lopesianum is a rare endemism from the Iberian Peninsula, occurring at the northeastern border between Portugal and Spain. It is classified as Endangered, due to its highly fragmented geographical occupation, facing a high risk of extinction in the Portuguese territory, within 20 years. Here, we describe for the first time the chemical characterization of extracts of the species concerning total phenol content, flavonoid content and antioxidant properties. The profile of high performance liquid chromatography with diode array detector (HPLC-DAD) of the polyphenol-enriched fraction of plant extracts was also performed, showing the great potential of the species as a source of bioactive phytochemical compounds. A. lopesianum’s potential for neuroprotection was revealed by a significant acetylcholinesterase inhibitory activity and also by a neuroprotective effect on a human cell model of neurodegeneration. Moreover, this is the first report describing a successful procedure for the in vitro propagation of this endangered species. The comparison of phenolic content and the HPLC-DAD profile of wild and in vitro propagated plants revealed that in vitro plants maintain the ability to produce secondary metabolites, but the profiles are differentially affected by the growth regulators. The results presented here greatly contribute to the value for this species regarding its potential as a source of phytochemicals with prospective neuroprotective health benefits. Full article
(This article belongs to the Special Issue Free Radicals)
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Open AccessArticle Relevance of the Mention of Antioxidant Properties in Yogurt Labels: In Vitro Evaluation and Chromatographic Analysis
Antioxidants 2013, 2(2), 62-76; doi:10.3390/antiox2020062
Received: 8 April 2013 / Revised: 29 May 2013 / Accepted: 6 June 2013 / Published: 18 June 2013
Cited by 2 | PDF Full-text (596 KB) | HTML Full-text | XML Full-text
Abstract
The purpose of the inclusion of fruit (natural additives) in yogurt aims to increase its antioxidant activity and functionality. Herein, a comparative study of the antioxidant potential of yogurts with pieces of various fruits was performed, including yogurts with mention of antioxidant [...] Read more.
The purpose of the inclusion of fruit (natural additives) in yogurt aims to increase its antioxidant activity and functionality. Herein, a comparative study of the antioxidant potential of yogurts with pieces of various fruits was performed, including yogurts with mention of antioxidant properties in the label. Free radicals scavenging activity, reducing power and inhibition of lipid peroxidation were evaluated by in vitro assays, as were the contents in antioxidants such as phenolics, flavonoids, sugars and tocopherols. After analyzing thirteen yogurts containing fruit pieces and a natural one (control), the most interesting were yogurts with pieces of berries (for phenolics, flavonoids and 2,2-dipheny-1-picrylhydrazyl (DPPH) scavenging activity), pineapple (for reducing power), blackberry (for β-carotene bleaching inhibition), blackberry “antioxidant” (for tocopherols) and cherry (for sugars). The mention of “antioxidant” in the label was relevant for tocopherols, sugars, DPPH scavenging activity and reducing power. No synergisms were observed in yogurts prepared with pieces of different fruits. Nevertheless, the addition of fruit pieces to yogurt was favorable for antioxidant content, increasing the protection of the consumer against diseases related to oxidative stress. Full article
(This article belongs to the Special Issue Free Radicals)

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