Special Issue "Plant Antioxidants"

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

Deadline for manuscript submissions: closed (31 July 2013)

Special Issue Editors

Guest Editor
Dr. Ehab A. Abourashed

Department of Pharmaceutical Sciences, College of Pharmacy / DH 206, Chicago State University, Chicago, IL 60628, USA
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Fax: 773-821-2595
Interests: evaluation of the antioxidant activities of natural products; plant secondary metabolites and herbal dietary supplements; characterization of the physicochemical properties and structure-activity relationships of flavonoid/phenolic compounds
Guest Editor
Prof. Dr. Luca Sebastiani

Life Sciences Institute – BioLabs, Piazza Martiri Libertà 33, 56127, Pisa, Italy
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Fax: +39 050 883495
Interests: plant biotechnology; plant biochemistry; secondary metabolites; biodiversity characterization; food quality; antioxidant; oxidative stress

Special Issue Information

Dear Colleagues,

Oxidative processes are ubiquitous in nature and they play a pivotal role in sustaining life on our planet. Uncontrolled oxidation, however, may result in significant damage to biological systems and to the environment that can be dangerous and costly. Prevalence and propagation of serious diseases, such as cancer, diabetes and many heart conditions; deterioration of the environment; as well as spoilage of products and commodities are examples of the damaging effects of oxidation and oxidative species. The ability of some antioxidants to act as pro-oxidants further complicates the situation. Consequently, the discovery and development of safe and effective antioxidants has been a major area of scientific research and, although many such agents currently exist, the plant kingdom continue to offer new chemical entities that have potential as sustainable, safe and effective antioxidants.

The purpose of this special issue of “Antioxidants” is to provide a current overview on the progress of research on plant secondary metabolites, or their analogs, that qualify as antioxidant agents. This will be achieved through the contributions of experts in the field of plant antioxidant discovery and development. You are thus invited to submit an original research or review article to this issue that focuses on such topics as chemistry of plant antioxidants; evaluation of antioxidant activity; development of antioxidant assays; antioxidant mechanisms; chemoprevention; health, medicine and environmental applications of antioxidants, improving antixotidant content in plants and plant derived products; and other related topics.

Dr. Ehab A. Abourashed
Prof. Dr. Luca Sebastiani
Guest Editors

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

  • plant secondary metabolites
  • antioxidant natural products/secondary metabolites
  • cancer chemoprevention
  • free-radical scavenging
  • semisynthetic analogs
  • antioxidant evaluation/assays
  • oxidative stress
  • antioxidant botanicals/herbal products

Published Papers (12 papers)

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Research

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Open AccessArticle Antioxidant Constituents of Cotoneaster melanocarpus Lodd.
Antioxidants 2013, 2(4), 265-272; doi:10.3390/antiox2040265
Received: 11 September 2013 / Revised: 22 September 2013 / Accepted: 27 September 2013 / Published: 24 October 2013
Cited by 1 | PDF Full-text (584 KB) | HTML Full-text | XML Full-text
Abstract
The aim of this study was the evaluation of the antioxidant capacity of Cotoneaster melanocarpus Lodd. and the identification of antioxidant active constituents of this plant. C. melanocarpus Lodd. is a shrub indigenous to Mongolia and used in Traditional Mongolian Medicine as a
[...] Read more.
The aim of this study was the evaluation of the antioxidant capacity of Cotoneaster melanocarpus Lodd. and the identification of antioxidant active constituents of this plant. C. melanocarpus Lodd. is a shrub indigenous to Mongolia and used in Traditional Mongolian Medicine as a styptic. Before extraction, the plant material was separated into three parts: young sterile shoots, older stems and leaves. All these parts were extracted with water, methanol, ethyl acetate, dichloromethane and hexane, successively. The methanolic extract of the sterile shoots showed the highest antioxidant activity in the DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging assay (IC50 30.91 ± 2.97 µg/mL). This active extract was further analyzed with chromatographic methods. TLC fingerprinting and HPLC indicated the presence of the flavonol glycosides quercetin-3-O-rutinoside (rutin), quercetin-3-O-galactoside (hyperoside) and quercetin-3-O-glucoside (isoquercetin), ursolic acid as well as chlorogenic acid, neochlorogenic acid and cryptochlorogenic acid. The findings were substantiated with LC-MS. All identified compounds have antioxidant properties and therefore contribute to the radical scavenging activity of the whole plant. Full article
(This article belongs to the Special Issue Plant Antioxidants)
Open AccessArticle Characterization of Changes in Polyphenols, Antioxidant Capacity and Physico-Chemical Parameters during Lowbush Blueberry Fruit Ripening
Antioxidants 2013, 2(4), 216-229; doi:10.3390/antiox2040216
Received: 22 August 2013 / Revised: 24 September 2013 / Accepted: 27 September 2013 / Published: 15 October 2013
Cited by 7 | PDF Full-text (206 KB) | HTML Full-text | XML Full-text
Abstract
Changes in major polyphenols, antioxidant capacity, and selected physico-chemical parameters were examined in lowbush blueberry during fruit ripening. Polyphenols (phenolic acids, flavonols, flavan-3-ols, and anthocyanins), density, soluble solid content, pH, titratable acidity, sugars, organic acids, and antioxidant capacity were determined in fruits of
[...] Read more.
Changes in major polyphenols, antioxidant capacity, and selected physico-chemical parameters were examined in lowbush blueberry during fruit ripening. Polyphenols (phenolic acids, flavonols, flavan-3-ols, and anthocyanins), density, soluble solid content, pH, titratable acidity, sugars, organic acids, and antioxidant capacity were determined in fruits of four maturities: green, pink/red, blue, and over-mature. Highest concentrations of flavonols, flavan-3-ols, and phenolic acids were in green fruits: 168 ± 107, 119 ± 29 and 543 ± 91 mg/100 g dry weight (DW) respectively. Highest anthocyanin levels were found in blue and over-mature fruits (1011–1060 mg/100 DW). Chlorogenic acid was the most abundant phenolic acid and quercetin-3-O-galactoside the most abundant flavonol in all maturities. Epicatechin was the most abundant flavan-3-ol in green fruits (80 ± 20 mg/100 DW), and catechin was the most abundant in other maturity stages. Increase of glucose and fructose and decrease of organic acids were observed during fruit ripening. Among six organic acids found, quinic acid (1.7–9.5 mg/100 mg DW) was the most abundant throughout the fruit ontogeny. Soluble solids, pH, and density increased with maturity while, titratable acidity decreased. These findings can be helpful in optimizing harvest and processing operations in lowbush blueberry fruits. Full article
(This article belongs to the Special Issue Plant Antioxidants)
Open AccessArticle Evaluation of Antioxidant Properties and Phenolic Composition of Fruit Tea Infusions
Antioxidants 2013, 2(4), 206-215; doi:10.3390/antiox2040206
Received: 1 August 2013 / Revised: 18 September 2013 / Accepted: 22 September 2013 / Published: 30 September 2013
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Abstract
The popularity of fruit tea is increasing in the world because of its antioxidant properties and attractive taste. The aim of this study was to determine and compare the antioxidant property and phenolic composition of 16 different fruit teas. The antioxidant property and
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The popularity of fruit tea is increasing in the world because of its antioxidant properties and attractive taste. The aim of this study was to determine and compare the antioxidant property and phenolic composition of 16 different fruit teas. The antioxidant property and total phenol content of fruit teas depending on the extraction condition (water temperature) were examined using the ABTS (2,2-azinobis[3-ethylbenzothiazoline-6-sulphonic acid]) method and the Folin-Ciocalteu method, respectively. The contents of total flavonoid and total anthocyanin of fruit teas was determined by using the UV/Vis spectrophotometric method. The phenolic composition was determined and quantified by using high performance liquid chromatography and photodiode array detection (HPLC-PDA). The highest total phenol content and antioxidant capacity were determined in pomegranate (I). The highest contents of total flavonoid and total anthocyanin were determined in peach (III) and blackberry (I), respectively. Chlorogenic acid, quercetin, myricetin, rutin, rosmarinic acid and ferulic acid were determined in fruit teas. A water temperature of 100 °C was the most effective to extract the highest contents of total phenols, total flavonoids, total anthocyanins and the highest antioxidant capacity in 16 different fruit teas. The purpose of this study was to determine the effect of water temperature on the extraction and quantify the various phenolic compounds in fruit teas by HPLC method for industrial application in producing the extracts. Full article
(This article belongs to the Special Issue Plant Antioxidants)
Open AccessCommunication Antioxidant Activity and Phenolic Content of Streblus asper Leaves from Various Drying Methods
Antioxidants 2013, 2(3), 156-166; doi:10.3390/antiox2030156
Received: 7 June 2013 / Revised: 31 July 2013 / Accepted: 23 August 2013 / Published: 30 August 2013
Cited by 4 | PDF Full-text (385 KB) | HTML Full-text | XML Full-text
Abstract
Aqueous and ethanol extracts of oven and freeze-dried Streblus asper leaves were investigated using DPPH assay. The presence of phenolic compounds and flavonoids in the extracts, which were detected by Folin and colorimetric assays, respectively, may be responsible for the antioxidant activities of
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Aqueous and ethanol extracts of oven and freeze-dried Streblus asper leaves were investigated using DPPH assay. The presence of phenolic compounds and flavonoids in the extracts, which were detected by Folin and colorimetric assays, respectively, may be responsible for the antioxidant activities of S. asper. The different drying treatments resulted in significant differences (p < 0.05) in the antioxidant properties as well as the phenolic and flavonoid contents of the S. asper extracts. Freeze-dried S. asper leaf extracts exhibited high DPPH radical scavenging activity ranging from 69.48% ± 0.03% to 89.25% ± 0.01% at concentrations ranging from 0 to 1 mg/mL, significantly higher compared with the oven-dried extracts which were in the range of 68.56% ± 0.01% to 86.68% ± 0.01%. Generally, the 70% ethanol extract of the freeze-dried samples exhibited higher phenolic and flavonoid content than the aqueous extract, with values of 302.85 ± 0.03 mg GAE/g and 22.70 ± 0.02 mg QE/g compared with 226.8 ± 0.03 mg GAE/g and 15.38 ± 0.05 mg QE/g, respectively. This study showed that S. asper leaf extracts contain a number of health promoting bioactive compounds, such as phenolic compounds, and are potential sources of natural antioxidants. Full article
(This article belongs to the Special Issue Plant Antioxidants)
Open AccessArticle Evaluation of Antioxidant Status of Two Limoniastrum Species Growing Wild in Tunisian Salty Lands
Antioxidants 2013, 2(3), 122-131; doi:10.3390/antiox2030122
Received: 13 June 2013 / Revised: 19 July 2013 / Accepted: 23 July 2013 / Published: 2 August 2013
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Abstract
We aim to highlight the differential antioxidant status of Limoniastrum guyonianum and Limoniastrum monopetalum in relation to their respective chemical and location characteristics. Metabolite analysis revealed similar contents in phenolic, flavonoïds, sugars and chlorophyll in the two species’ leaves. Higher amounts of proline
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We aim to highlight the differential antioxidant status of Limoniastrum guyonianum and Limoniastrum monopetalum in relation to their respective chemical and location characteristics. Metabolite analysis revealed similar contents in phenolic, flavonoïds, sugars and chlorophyll in the two species’ leaves. Higher amounts of proline (Pro), carotenoïds (Carot), sodium (Na) and potassium (K) were measured in L. monopetalum leaves relative to L. guyonianum ones. While the two Limoniastrum species have similar free radical DPPH (2,2-diphenyl-1-picrylhydrazyl) scavenging activity, L. guyonianum showed more than two-fold higher ferrous ions chelating activity relative to L. monopetalum. However, highest reducing power activity was observed in L. monopetalum. Thiobarbituric acid-reactive substances (TBARS) determination indicated that L. monopetalum behave better lipid membrane integrity relative to L. guyonianum. These findings suggested that the lesser stressful state of L. monopetalum was related to higher metabolites accumulation and reducing capacity compared to L. guyonianum. Full article
(This article belongs to the Special Issue Plant Antioxidants)
Open AccessArticle Antioxidant, Iron Chelating and Tyrosinase Inhibitory Activities of Extracts from Talinum triangulare Leach Stem
Antioxidants 2013, 2(3), 90-99; doi:10.3390/antiox2030090
Received: 11 May 2013 / Revised: 14 June 2013 / Accepted: 28 June 2013 / Published: 17 July 2013
Cited by 2 | PDF Full-text (214 KB) | HTML Full-text | XML Full-text
Abstract
The aim of this work is to evaluate the antioxidant activity against the radical species DPPH, the reducing capacity against Fe II ions, and the inhibitory activity on the tyrosinase enzyme of the T. triangulare. Hydromethanolic crude extract provided two fractions after
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The aim of this work is to evaluate the antioxidant activity against the radical species DPPH, the reducing capacity against Fe II ions, and the inhibitory activity on the tyrosinase enzyme of the T. triangulare. Hydromethanolic crude extract provided two fractions after the liquid/liquid partition with chloroform. The Folin-Ciocalteu method determined the total phenolic content of the crude extract (CE) and the hydromethanolic fraction (Fraction 1), resulting in a concentration of 0.5853 g/100 g for Fraction 1, and 0.1400 g/100 g for the CE. Taking into account the results of the DPPH, the free radical scavenging capacity was confirmed. The formation of complexes with Fe II ions was evaluated by UV/visible spectrometry; results showed that CE has complexing power similar to the positive control (Gingko biloba extract).The inhibitory capacity of samples against the tyrosinase enzyme was determined by the oxidation of L-DOPA, providing IC50 values of 13.3 μg·mL−1 (CE) and 6.6 μg·mL−1 (Fraction 1). The values indicate that Fraction 1 was more active and showed a higher inhibitory power on the tyrosinase enzyme than the ascorbic acid, used as positive control. The hydromethanolic extract of T. triangulare proved to have powerful antioxidant activity and to inhibit the tyrosinase enzyme; its potential is increased after the partition with chloroform. Full article
(This article belongs to the Special Issue Plant Antioxidants)
Figures

Open AccessArticle Antioxidant Potential of Bark Extracts from Boreal Forest Conifers
Antioxidants 2013, 2(3), 77-89; doi:10.3390/antiox2030077
Received: 6 May 2013 / Revised: 13 June 2013 / Accepted: 28 June 2013 / Published: 11 July 2013
Cited by 3 | PDF Full-text (438 KB) | HTML Full-text | XML Full-text
Abstract
The bark of boreal forest conifers has been traditionally used by Native Americans to treat various ailments and diseases. Some of these diseases involve reactive oxygen species (ROS) that can be prevented by the consumption of antioxidants such as phenolic compounds that can
[...] Read more.
The bark of boreal forest conifers has been traditionally used by Native Americans to treat various ailments and diseases. Some of these diseases involve reactive oxygen species (ROS) that can be prevented by the consumption of antioxidants such as phenolic compounds that can be found in medicinal plants. In this study, ultrasonic assisted extraction has been performed under various solvent conditions (water:ethanol mixtures) on the bark of seven boreal forest conifers used by Native Americans including: Pinus strobus, Pinus resinosa, Pinus banksiana, Picea mariana, Picea glauca, Larix laricina, and Abies balsamea. The total phenolic content, as well as ORACFL potency and cellular antioxidant activity (IC50), were evaluated for all bark extracts, and compared with the standardized water extract of Pinus maritima bark (Pycnogenol), which showed clinical efficiency to prevent ROS deleterious effects. The best overall phenolic extraction yield and antioxidant potential was obtained with Picea glauca and Picea mariana. Interestingly, total phenolic content of these bark extracts was similar to Pycnogenol but their antioxidant activity were higher. Moreover, most of the extracts did not inhibit the growth of human skin fibroblasts, WS1. A significant correlation was found between the total phenolic content and the antioxidant activity for water extracts suggesting that these compounds are involved in the activity. Full article
(This article belongs to the Special Issue Plant Antioxidants)

Review

Jump to: Research

Open AccessReview Biological Activities of Phenolic Compounds of Extra Virgin Olive Oil
Antioxidants 2014, 3(1), 1-23; doi:10.3390/antiox3010001
Received: 16 October 2013 / Revised: 27 November 2013 / Accepted: 28 November 2013 / Published: 20 December 2013
Cited by 23 | PDF Full-text (387 KB) | HTML Full-text | XML Full-text
Abstract
Over the last few decades, multiple biological properties, providing antioxidant, anti-inflammatory, chemopreventive and anti-cancer benefits, as well as the characteristic pungent and bitter taste, have been attributed to Extra Virgin Olive Oil (EVOO) phenols. In particular, growing efforts have been devoted to the
[...] Read more.
Over the last few decades, multiple biological properties, providing antioxidant, anti-inflammatory, chemopreventive and anti-cancer benefits, as well as the characteristic pungent and bitter taste, have been attributed to Extra Virgin Olive Oil (EVOO) phenols. In particular, growing efforts have been devoted to the study of the antioxidants of EVOO, due to their importance from health, biological and sensory points of view. Hydrophilic and lipophilic phenols represent the main antioxidants of EVOO, and they include a large variety of compounds. Among them, the most concentrated phenols are lignans and secoiridoids, with the latter found exclusively in the Oleaceae family, of which the drupe is the only edible fruit. In recent years, therefore, we have tackled the study of the main properties of phenols, including the relationships between their biological activity and the related chemical structure. This review, in fact, focuses on the phenolic compounds of EVOO, and, in particular, on their biological properties, sensory aspects and antioxidant capacity, with a particular emphasis on the extension of the product shelf-life. Full article
(This article belongs to the Special Issue Plant Antioxidants)
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Open AccessReview Antioxidant Defenses in Plants with Attention to Prunus and Citrus spp.
Antioxidants 2013, 2(4), 340-369; doi:10.3390/antiox2040340
Received: 14 July 2013 / Revised: 8 October 2013 / Accepted: 28 October 2013 / Published: 26 November 2013
Cited by 8 | PDF Full-text (1019 KB) | HTML Full-text | XML Full-text | Correction | Supplementary Files
Abstract
This short review briefly introduces the formation of reactive oxygen species (ROS) as by-products of oxidation/reduction (redox) reactions, and the ways in which the antioxidant defense machinery is involved directly or indirectly in ROS scavenging. Major antioxidants, both enzymatic and non enzymatic, that
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This short review briefly introduces the formation of reactive oxygen species (ROS) as by-products of oxidation/reduction (redox) reactions, and the ways in which the antioxidant defense machinery is involved directly or indirectly in ROS scavenging. Major antioxidants, both enzymatic and non enzymatic, that protect higher plant cells from oxidative stress damage are described. Biochemical and molecular features of the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX) are discussed because they play crucial roles in scavenging ROS in the different cell compartments and in response to stress conditions. Among the non enzymatic defenses, particular attention is paid to ascorbic acid, glutathione, flavonoids, carotenoids, and tocopherols. The operation of ROS scavenging systems during the seasonal cycle and specific developmental events, such as fruit ripening and senescence, are discussed in relation to the intense ROS formation during these processes that impact fruit quality. Particular attention is paid to Prunus and Citrus species because of the nutritional and antioxidant properties contained in these commonly consumed fruits. Full article
(This article belongs to the Special Issue Plant Antioxidants)
Open AccessReview Bioavailability of Plant-Derived Antioxidants
Antioxidants 2013, 2(4), 309-325; doi:10.3390/antiox2040309
Received: 22 September 2013 / Revised: 22 October 2013 / Accepted: 25 October 2013 / Published: 5 November 2013
Cited by 9 | PDF Full-text (439 KB) | HTML Full-text | XML Full-text
Abstract
Natural products with antioxidant properties have been extensively utilized in the pharmaceutical and food industry and have also been very popular as health-promoting herbal products. This review provides a summary of the literature published around the first decade of the 21st century regarding
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Natural products with antioxidant properties have been extensively utilized in the pharmaceutical and food industry and have also been very popular as health-promoting herbal products. This review provides a summary of the literature published around the first decade of the 21st century regarding the oral bioavailability of carotenoids, polyphenols and sulfur compounds as the three major classes of plant-derived antioxidants. The reviewed original research includes more than 40 compounds belonging to the above mentioned classes of natural antioxidants. In addition, related reviews published during the same period have been cited. A brief introduction to general bioavailability-related definitions, procedures and considerations is also included. Full article
(This article belongs to the Special Issue Plant Antioxidants)
Open AccessReview Phenolic Compounds in Apple (Malus x domestica Borkh.): Compounds Characterization and Stability during Postharvest and after Processing
Antioxidants 2013, 2(3), 181-193; doi:10.3390/antiox2030181
Received: 8 August 2013 / Revised: 3 September 2013 / Accepted: 6 September 2013 / Published: 18 September 2013
Cited by 8 | PDF Full-text (1158 KB) | HTML Full-text | XML Full-text
Abstract
This paper summarizes the information on the occurrence of phenolic compounds in apple (Malus x domestica Borkh.) fruit and juice, with special reference to their health related properties. As phytochemical molecules belonging to polyphenols are numerous, we will focus on the main
[...] Read more.
This paper summarizes the information on the occurrence of phenolic compounds in apple (Malus x domestica Borkh.) fruit and juice, with special reference to their health related properties. As phytochemical molecules belonging to polyphenols are numerous, we will focus on the main apples phenolic compounds with special reference to changes induced by apple cultivar, breeding approaches, fruit postharvest and transformation into juice. Full article
(This article belongs to the Special Issue Plant Antioxidants)
Open AccessReview The Antioxidants Changes in Ornamental Flowers during Development and Senescence
Antioxidants 2013, 2(3), 132-155; doi:10.3390/antiox2030132
Received: 11 July 2013 / Revised: 24 July 2013 / Accepted: 26 July 2013 / Published: 6 August 2013
Cited by 7 | PDF Full-text (307 KB) | HTML Full-text | XML Full-text
Abstract
The concentration of antioxidant compounds is constitutive and variable from species to species and is also variable considering the development of the plant tissue. In this review, we take into consideration the antioxidant changes and the physiological, biochemical and molecular factors that are
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The concentration of antioxidant compounds is constitutive and variable from species to species and is also variable considering the development of the plant tissue. In this review, we take into consideration the antioxidant changes and the physiological, biochemical and molecular factors that are able to modulate the accumulation of antioxidant compounds in ornamental flowers during the whole development process until the senescence. Many ornamental flowers are natural sources of very important bioactive compounds with benefit to the human health and their possible role as dietary components has been reported. The most part of antioxidants are flower pigments such as carotenoids and polyphenols, often present in higher concentration compared with the most common fruits and vegetables. The antioxidants content changes during development and during senescence many biochemical systems and molecular mechanisms are activated to counteract the increase of reactive oxygen species and free radicals. There is a tight correlation between antioxidants and senescence processes and this aspect is detailed and appropriately discussed. Full article
(This article belongs to the Special Issue Plant Antioxidants)

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