Special Issue "Marine Algal Antioxidants"

A special issue of Antioxidants (ISSN 2076-3921). This special issue belongs to the section "Natural and Synthetic Antioxidants".

Deadline for manuscript submissions: 15 October 2019.

Special Issue Editors

Dr. Christophe Brunet
E-Mail Website
Guest Editor
Stazione Zoologica Anton Dohrn, Naples, Italy
Interests: Microalgal ecology; photophysiology; pigments; antioxidants; algal biomass and cultivation; marine biotechnology
Dr. Clementina Sansone
E-Mail Website
Guest Editor
Stazione Zoologica Anton Dohrn, Naples, Italy
Tel. +390815833221
Interests: Marine Biotechnology; drug discovery; cell biology; pharmaceuticals; nutraceuticals and cosmetics

Special Issue Information

Dear colleagues,

It is a pleasure for us to invite you to contribute to this Special Issue of Antioxidants by submitting original research papers or review articles focusing on Marine Algal Antioxidants.

The aim of this Special Issue is to present recent investigations into marine algal antioxidants and antioxidant networks functioning in algae.

The topics covered in this Special Issue will spawn from the diversity of antioxidant molecules in marine algae to their ecological role in marine ecosystems and their potential interest for biotechnological applications. Since the huge ecological forcing difference between marine and terrestrial systems, related for instance to the diversity of carotenoids reported in the marine algal world, compared to terrestrial plants, it is expected that antioxidant molecules (diversity, production, role) in marine algae also present peculiar properties.

This Special Issue aims to present data and the state-of-art on the way to increase antioxidant production for their exploitation in different fields, such as nutraceutics or cosmetics. On this topic, the plus-value of algal biodiversity for antioxidant molecule production will be also questioned.

There is no way to improve the sustainable and efficient production of bioactive molecules from photosynthetic organisms without an ecological knowledge of both the targeted organisms and family of molecules. The latter enters into finely-tuned mechanisms of defence, protection and/or repair acting in a balanced syntony with the photosynthetic and metabolism activity, modulated by adaptation, acclimation or regulation features operated by the organisms.

While a plethora of antioxidant molecules produced by higher plants are known and have been well-documented by many reports, little is known about the bioactive molecules from marine algae, with the exception of the carotenoids pool. Other families of antioxidant molecules are found in microalgae, such as phenolic compounds (e.g., flavonoids), lipophilic molecules synthesized by photosynthetic organisms, such as ascorbic acid (vitamin c) and tocopherols (vitamin E), and glutathione and phycobiliproteins present in few algal groups. While it is reported that these families of molecules with potential antioxidant roles are present in microalgae, little is known about their diversity, role or activity.

We look forward to receiving many contributions and stimulating a productive discussion on this exciting thematic of marine algal antioxidants.

Best regards,

Dr. Christophe Brunet
Dr. Clementina Sansone
Guest Editors

Manuscript Submission Information

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. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short 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 thoroughly refereed through a single-blind 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 monthly 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 1200 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Antioxidant biodiversity
  • Vitamins
  • Flavonoids
  • Phycobiliproteins
  • Phenolic compounds
  • Carotenoids
  • Antioxidant network and protective mechanisms in microalgae
  • Sustainable production of microalgal antioxidant molecules
  • Analytical methodology: Antioxidant molecules determination
  • Analytical methodology: Antioxidant activity determination
  • Antioxidant activity in vitro
  • Molecular pathways activated by microalgal antioxidants

Published Papers (7 papers)

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Research

Open AccessCommunication
Promises and Challenges of Microalgal Antioxidant Production
Antioxidants 2019, 8(7), 199; https://doi.org/10.3390/antiox8070199 - 27 Jun 2019
Abstract
The exploration of natural antioxidants for nutraceuticals and pharmaceuticals industries has recently increased. This communication aims to grasp the relevance of microalgae in the panorama of natural antioxidant molecules supply to industrial applications as alternatives and/or complements to those typically used from higher [...] Read more.
The exploration of natural antioxidants for nutraceuticals and pharmaceuticals industries has recently increased. This communication aims to grasp the relevance of microalgae in the panorama of natural antioxidant molecules supply to industrial applications as alternatives and/or complements to those typically used from higher plants. Microalgal richness in antioxidant compounds and scavenging ability compared to higher plants is discussed in the context of microalgal biodiversity. We mainly focus on families of powerful antioxidant compounds that have been scarcely investigated in microalgae, such as phenolic compounds, sterols, or vitamins, discussing the promise and challenges of microalgae as providers of health benefits, for instance, through their use as functional food ingredients. Full article
(This article belongs to the Special Issue Marine Algal Antioxidants)
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Open AccessArticle
Fucoxanthin, A Carotenoid Derived from Phaeodactylum tricornutum Exerts Antiproliferative and Antioxidant Activities In Vitro
Antioxidants 2019, 8(6), 183; https://doi.org/10.3390/antiox8060183 - 19 Jun 2019
Abstract
Microalgae contain a multitude of nutrients and can be grown sustainably. Fucoxanthin, a carotenoid from Phaeodactylum tricornutum, could have beneficial health effects. Therefore, we investigated the anti-inflammatory, antioxidative and antiproliferative effects of fucoxanthin derived from this diatom in vitro. The effects of purified [...] Read more.
Microalgae contain a multitude of nutrients and can be grown sustainably. Fucoxanthin, a carotenoid from Phaeodactylum tricornutum, could have beneficial health effects. Therefore, we investigated the anti-inflammatory, antioxidative and antiproliferative effects of fucoxanthin derived from this diatom in vitro. The effects of purified fucoxanthin on metabolic activity were assessed in blood mononuclear cells and different cell lines. In cell lines, caspase 3/7 activity was also analyzed. Nitrogen monoxide release and mRNA-expression of proinflammatory cytokines were measured. For antioxidant assays, cell free assays were conducted. Additionally, the antioxidant effect in neutrophils was quantified and glutathione was determined in HeLa cells. The results show that neither did fucoxanthin have anti-inflammatory properties nor did it exert cytotoxic effects on mononuclear cells. However, the metabolic activity of cell lines was decreased up to 58% and fucoxanthin increased the caspase 3/7 activity up to 4.6-fold. Additionally, dose-dependent antioxidant effects were detected, resulting in a 63% decrease in chemiluminescence in blood neutrophils and a 3.3-fold increase in the ratio of reduced to oxidized glutathione. Our studies show that fucoxanthin possesses antiproliferative and antioxidant activities in vitro. Hence, this carotenoid or the whole microalgae P. tricornutum could be considered as a food or nutraceutical in human nutrition, showcasing beneficial health effects. Full article
(This article belongs to the Special Issue Marine Algal Antioxidants)
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Open AccessArticle
Antioxidant and Photoprotection Networking in the Coastal Diatom Skeletonema marinoi
Antioxidants 2019, 8(6), 154; https://doi.org/10.3390/antiox8060154 - 01 Jun 2019
Cited by 1
Abstract
Little is known on the antioxidant activity modulation in microalgae, even less in diatoms. Antioxidant molecule concentrations and their modulation in microalgae has received little attention and the interconnection between light, photosynthesis, photoprotection, and antioxidant network in microalgae is still unclear. To fill [...] Read more.
Little is known on the antioxidant activity modulation in microalgae, even less in diatoms. Antioxidant molecule concentrations and their modulation in microalgae has received little attention and the interconnection between light, photosynthesis, photoprotection, and antioxidant network in microalgae is still unclear. To fill this gap, we selected light as external forcing to drive physiological regulation and acclimation in the costal diatom Skeletonema marinoi. We investigated the role of light regime on the concentration of ascorbic acid, phenolic compounds and among them flavonoids and their connection with photoprotective mechanisms. We compared three high light conditions, differing in either light intensity or wave distribution, with two low light conditions, differing in photoperiod, and a prolonged darkness. The change in light distribution, from sinusoidal to square wave distribution was also investigated. Results revealed a strong link between photoprotection, mainly relied on xanthophyll cycle operation, and the antioxidant molecules and activity modulation. This study paves the way for further investigation on the antioxidant capacity of diatoms, which resulted to be strongly forced by light conditions, also in the view of their potential utilization in nutraceuticals or new functional cosmetic products. Full article
(This article belongs to the Special Issue Marine Algal Antioxidants)
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Open AccessArticle
Red Light Control of β-Carotene Isomerisation to 9-cis β-Carotene and Carotenoid Accumulation in Dunaliella salina
Antioxidants 2019, 8(5), 148; https://doi.org/10.3390/antiox8050148 - 27 May 2019
Abstract
Dunaliella salina is a rich source of 9-cis β-carotene, which has been identified as an important biomolecule in the treatment of retinal dystrophies and other diseases. We previously showed that chlorophyll absorption of red light photons in D. salina is coupled with oxygen [...] Read more.
Dunaliella salina is a rich source of 9-cis β-carotene, which has been identified as an important biomolecule in the treatment of retinal dystrophies and other diseases. We previously showed that chlorophyll absorption of red light photons in D. salina is coupled with oxygen reduction and phytoene desaturation, and that it increases the pool size of β-carotene. Here, we show for the first time that growth under red light also controls the conversion of extant all-trans β-carotene to 9-cis β-carotene by β-carotene isomerases. Cells illuminated with red light from a light emitting diode (LED) during cultivation contained a higher 9-cis β-carotene content compared to cells illuminated with white or blue LED light. The 9-cis/all-trans β-carotene ratio in red light treated cultures reached >2.5 within 48 h, and was independent of light intensity. Illumination using red light filters that eliminated blue wavelength light also increased the 9-cis/all-trans β-carotene ratio. With norflurazon, a phytoene desaturase inhibitor which blocked downstream biosynthesis of β-carotene, extant all-trans β-carotene was converted to 9-cis β-carotene during growth with red light and the 9-cis/all-trans β-carotene ratio was ~2. With blue light under the same conditions, 9-cis β-carotene was likely destroyed at a greater rate than all-trans β-carotene (9-cis/all-trans ratio 0.5). Red light perception by the red light photoreceptor, phytochrome, may increase the pool size of anti-oxidant, specifically 9-cis β-carotene, both by upregulating phytoene synthase to increase the rate of biosynthesis of β-carotene and to reduce the rate of formation of reactive oxygen species (ROS), and by upregulating β-carotene isomerases to convert extant all-trans β-carotene to 9-cis β-carotene. Full article
(This article belongs to the Special Issue Marine Algal Antioxidants)
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Open AccessArticle
Optimization of Microwave-Assisted Extraction of Polysaccharides from Ulva pertusa and Evaluation of Their Antioxidant Activity
Antioxidants 2019, 8(5), 129; https://doi.org/10.3390/antiox8050129 - 14 May 2019
Cited by 3
Abstract
The use of green marine seaweed Ulva spp. as foods, feed supplements, and functional ingredients has gained increasing interest. Microwave-assisted extraction technology was employed to improve the extraction yield and composition of Ulva pertusa polysaccharides. The antioxidant activity of ulvan was also evaluated. [...] Read more.
The use of green marine seaweed Ulva spp. as foods, feed supplements, and functional ingredients has gained increasing interest. Microwave-assisted extraction technology was employed to improve the extraction yield and composition of Ulva pertusa polysaccharides. The antioxidant activity of ulvan was also evaluated. The impacts of four independent variables, i.e., extraction time (X1, 30 to 60 min), power (X2, 500 to 700 W), water-to-raw-material ratio (X3, 40 to 70), and pH (X4, 5 to 7) were evaluated. The chemical structure of different polysaccharides fractions was investigated via FT-IR and the determination of their antioxidant activities. A response surface methodology based on a Box–Behnken design (BBD) was used to optimize the extraction conditions as follows: extraction time of 43.63 min, power level of 600 W, water-to-raw-material ratio of 55.45, pH of 6.57, and maximum yield of 41.91%, with a desired value of 0.381. Ulvan exerted a strong antioxidant effect against 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) and showed reducing power in vitro. Ulvan protected RAW 264.7 cells against H2O2-induced oxidative stress by upregulating the expression and enhancing the activity of oxidative enzymes such as superoxide dismutase (SOD) and superoxide dismutase (CAT). The results suggest that the polysaccharides from U. pertusa might be promising bioactive compounds for commercial use. Full article
(This article belongs to the Special Issue Marine Algal Antioxidants)
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Open AccessArticle
Carotenoid Production by Dunaliella salina under Red Light
Antioxidants 2019, 8(5), 123; https://doi.org/10.3390/antiox8050123 - 07 May 2019
Cited by 1
Abstract
The halotolerant photoautotrophic marine microalga Dunaliella salina is one of the richest sources of natural carotenoids. Here we investigated the effects of high intensity blue, red and white light from light emitting diodes (LED) on the production of carotenoids by strains of D. [...] Read more.
The halotolerant photoautotrophic marine microalga Dunaliella salina is one of the richest sources of natural carotenoids. Here we investigated the effects of high intensity blue, red and white light from light emitting diodes (LED) on the production of carotenoids by strains of D. salina under nutrient sufficiency and strict temperature control favouring growth. Growth in high intensity red light was associated with carotenoid accumulation and a high rate of oxygen uptake. On transfer to blue light, a massive drop in carotenoid content was recorded along with very high rates of photo-oxidation. In high intensity blue light, growth was maintained at the same rate as in red or white light, but without carotenoid accumulation; transfer to red light stimulated a small increase in carotenoid content. The data support chlorophyll absorption of red light photons to reduce plastoquinone in photosystem II, coupled to phytoene desaturation by plastoquinol:oxygen oxidoreductase, with oxygen as electron acceptor. Partitioning of electrons between photosynthesis and carotenoid biosynthesis would depend on both red photon flux intensity and phytoene synthase upregulation by the red light photoreceptor, phytochrome. Red light control of carotenoid biosynthesis and accumulation reduces the rate of formation of reactive oxygen species (ROS) as well as increases the pool size of anti-oxidant. Full article
(This article belongs to the Special Issue Marine Algal Antioxidants)
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Open AccessArticle
The Long-Term Algae Extract (Chlorella and Fucus sp) and Aminosulphurate Supplementation Modulate SOD-1 Activity and Decrease Heavy Metals (Hg++, Sn) Levels in Patients with Long-Term Dental Titanium Implants and Amalgam Fillings Restorations
Antioxidants 2019, 8(4), 101; https://doi.org/10.3390/antiox8040101 - 16 Apr 2019
Cited by 2
Abstract
The toxicity of heavy metals such as Hg++ is a serious risk for human health. We evaluated whether 90 days of nutritional supplementation (d90, n = 16) with Chlorella vulgaris (CV) and Fucus sp extracts in conjunction with aminosulphurate (nutraceuticals) supplementation could [...] Read more.
The toxicity of heavy metals such as Hg++ is a serious risk for human health. We evaluated whether 90 days of nutritional supplementation (d90, n = 16) with Chlorella vulgaris (CV) and Fucus sp extracts in conjunction with aminosulphurate (nutraceuticals) supplementation could detox heavy metal levels in patients with long-term titanium dental implants (average: three, average: 12 years in mouth) and/or amalgam fillings (average: four, average: 15 years) compared to baseline levels (d0: before any supplementation, n = 16) and untreated controls (without dental materials) of similar age (control, n = 21). In this study, we compared levels of several heavy metals/oligoelements in these patients after 90 days (n = 16) of nutritional supplementation with CV and aminozuphrates extract with their own baseline levels (d0, n = 16) and untreated controls (n = 21); 16 patients averaging 44 age years old with long-term dental amalgams and titanium implants for at least 10 years (average: 12 years) were recruited, as well as 21 non-supplemented controls (without dental materials) of similar age. The following heavy metals were quantified in hair samples as index of chronic heavy metal exposure before and after 90 days supplementation using inductively coupled plasma-mass spectrometry (ICP-MS) and expressed as μg/g of hair (Al, Hg++, Ba, Ag, Sb, As, Be, Bi, Cd, Pb, Pt, Tl, Th, U, Ni, Sn, and Ti). We also measured several oligoelements (Ca++, Mg++, Na+, K+, Cu++, Zn++, Mn++, Cr, V, Mo, B, I, P, Se, Sr, P, Co, Fe++, Ge, Rb, and Zr). The algae and nutraceutical supplementation during 90 consecutive days decreased Hg++, Ag, Sn, and Pb at 90 days as compared to baseline levels. The mercury levels at 90 days decreased as compared with the untreated controls. The supplementation contributed to reducing heavy metal levels. There were increased lithium (Li) and germanium (Ge) levels after supplementation in patients with long-term dental titanium implants and amalgams. They also (d90) increased manganesum (Mn++), phosphorum (P), and iron (Fe++) levels as compared with their own basal levels (d0) and the untreated controls. Finally, decreased SuperOxide Dismutase-1 (SOD-1) activity (saliva) was observed after 90 days of supplementation as compared with basal levels (before any supplementation, d0), suggesting antioxidant effects. Conversely, we detected increased SOD-1 activity after 90 days as compared with untreated controls. This SOD-1 regulation could induce antioxidant effects in these patients. The long-term treatment with algae extract and aminosulphurates for 90 consecutive days decreased certain heavy metal levels (Hg++, Ag, Sn, Pb, and U) as compared with basal levels. However, Hg++ and Sn reductions were observed after 90 days as compared with untreated controls (without dental materials). The dental amalgam restoration using activated nasal filters in conjunction with long-term nutritional supplementation enhanced heavy metals removal. Finally, the long-term supplementation with these algae and aminoazuphrates was safe and non-toxic in patients. These supplements prevented certain deficits in oligoelements without affecting their Na+/K+ ratios after long-term nutraceutical supplementation. Full article
(This article belongs to the Special Issue Marine Algal Antioxidants)
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