Mayalen Zubia

Antioxidant and cytotoxic activities of some red algae (Rhodophyta) from Brittany coasts (France)

We assessed the antioxidant activity of crude extracts from 24 rhodophyte species from Brittany coasts using three complementary methods (2,2-diphenyl-1-picryhydrazyl, reducing activity, and b-carotene-linoleic acid system). We also examined phenolic contents. Cytotoxic activities were determined with three different cancer cell lines. Four species (Aglaothamnion pseudobyssoides, Furcellaria fastigiata, Polysiphonia lanosa, and Heterosiphonia plumosa) had high antioxidant activity and high phenolic content. The extract from Brongniartella byssoides had the highest antioxidant potential, which was also found to be equivalent to the antioxidant activities of some commercial antioxidants. In the b-carotene system, extracts from Porphyra leucosticta and Porphyra purpurea had some specific antioxidant activity. Furthermore, Asparagopsis armata, B. byssoides and H. plumosa extracts had strong cytotoxic activities against Daudi and Jurkat cells.

Chemical composition of attached and drift specimens of Sargassum mangarevense and Turbinaria ornata (Phaeophyta: Fucales) from Tahiti, French Polynesia

Abstract The proximate composition, mineral and trace metal contents were determined for three different algal raw materials: attached Sargassum mangarevense, Turbinaria ornata and drift algae (almost entirely composed of these two species). Dietary fibre (38.1–42.8% dw) and ash (30.6–39.8% dw) were the most abundant constituents in all samples.A high protein content (13.2±1.9% dw) was found in S. mangarevense. All algae displayed similar amino acid patterns with a predominance of aspartic and glutamic acids (28.10–33.77% of total amino acids). Attached specimens had similar compositions of fatty acids, with a high concentration of polyunsaturated forms, especially C18 and C20. All samples showed a high mineral content, particularly in calcium, magnesium, potassium (T. ornata), iodine (S. mangarevense), iron and zinc. The drift algae usually accumulated more minerals than the attached algae. The potential use of both attached and drift algae as fertilisers, animal food and cosmetic products is discussed.

Sunscreen, antioxidant, and bactericide capacities of phlorotannins from the brown macroalga Halidrys siliquosa

The present study focused on a brown macroalga (Halidrys siliquosa), with a particular emphasis on polyphenols and their associated biological activities. Two fractions were obtained by liquid/liquid purification from a crude hydroethanolic extract: (i) an ethyl acetate fraction and (ii) an aqueous fraction. Total phenolic contents and antioxidant activities of extract and both fractions were assessed by in vitro tests (Folin–Ciocalteu test, 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, reducing power assay, superoxide anion scavenging assay, and β-carotene–linoleic acid system). For the most active fraction, i.e., the ethyl acetate fraction, the oxygen radical absorbance capacity (ORAC) value, antibacterial activities, and sunscreen potential (Sun Protection Factor and UV-A-Protection Factor) were tested in vitro. A high correlation found between antioxidant activities and total phenolic content was interpreted as the involvement of polyphenolic compounds in antioxidant mechanisms. Interestingly, the ethyl acetate fraction appeared to be a broad-spectrum UV absorber and showed a strong bactericidal activity against Pseudomonas aeruginosa, Staphylococcus aureus, and Escherichia coli. In this fraction, four phenolic compounds (trifuhalols and tetrafuhalols and, for the first time, diphlorethols and triphlorethols) were identified using 1D and 2D nuclear magnetic resonance (NMR) and MS analysis. These findings are promising for the use of H. siliquosa, abundant in Brittany, as a valuable source of photoprotectant molecules for sunscreen and cosmetic applications.

Mahorones, Highly Brominated Cyclopentenones from the Red Alga Asparagopsis taxiformis

The red alga Asparagopsis taxiformis (Rhodophyta, Bonnemaisoniaceae) has been shown to produce a large diversity of halogenated volatile organic compounds, with one to four carbons. As the distribution of this alga may expand worldwide, we implemented a research program that aims to understand the functions of its specialized metabolome in marine ecosystems. Phytochemical investigations performed on A. taxiformis gametophyte stages from the Indian Ocean revealed two new highly brominated cyclopentenones named mahorone (1) and 5-bromomahorone (2). They are the first examples of natural 2,3-dibromocyclopentenone derivatives. Their structure elucidation was achieved using spectrometric methods including NMR and MS. A standardized ecotoxicological assay was used as an assessment of their role in the environment, revealing high toxicities for both compounds (EC50 0.16 μM for 1 and 2). Additionally, both compounds were evaluated in antibacterial, antifungal, and cytotoxicity assays. Compounds 1 and 2 exhibit mild antibacterial activities against the human pathogen Acinetobacter baumannii.

Sargassum (Fucales, Phaeophyceae) in Mauritius and Reunion, western Indian Ocean : taxonomic revision and biogeography using hydrodynamic dispersal models

Mattio L., Zubia M., Loveday B, Crochelet E., Duong N., Payri C.E., Bhagooli R. and Bolton J.J. 2013. Sargassum (Fucales, Phaeophyceae) in Mauritius and Réunion, western Indian Ocean: taxonomic revision and biogeography using hydrodynamic dispersal models. Phycologia 52: 578–594. DOI: 10.2216/13-150.1 Mauritius and Réunion are part of the Mascarene Islands situated in the southwestern Indian Ocean, c. 800 km east of Madagascar. A total of 44 different Sargassum species and subspecific taxa was listed in the literature for these islands. This was a remarkable number for such isolated and small islands, and was more than have been recorded from Madagascar or other East African countries. The first aim of our study was to revise these species lists using newly collected specimens to provide a reliable and illustrated tool for the identification of the Mauritian and Réunion Sargassum. On the basis of morphological and molecular analyses, a total of six taxa was identified as S. cymosum f. borbonicum, S. obovatum, S. pfeifferae (reinstated), S. polycystum, S. portierianum and S. robillardii (stat. nov.). A seventh taxon, S. scopula, was identified from a herbarium collection but not re-collected. As a result of our taxonomic revision, we concluded that most of the species listed in the literature for both Mauritius and Réunion were misidentifications or synonyms, and we proposed three new taxonomic synonyms. The biogeography of the six Sargassum taxa was further investigated using local and regional hydrodynamic dispersal models. Results underlined the isolated position of the Mascarene Islands with (1) unlikely import of Sargassum in present-day conditions, (2) likely dispersal/exchanges within the archipelago and (3) a two-pronged export of Sargassum to the east coast of Madagascar and the Seychelles with a major stream northwestward and a weaker stream southwestward. These oceanic conditions had probably shaped the Sargassum diversity of the Mascarene Islands and in particular explained the endemicity of S. cymosum f. borbonicum and restricted distribution of S. obovatum, S. pfeifferae, S. robillardii and S. scopula.

Caulerpa consumption, nutritional value and farming in the Indo-Pacific region

In the Indo-Pacific region, several species of the green seaweed genus Caulerpa Lamouroux (1809) are very popular as human food because of their delicious taste and crunchy texture, which are pleasing to the palate, and because of their health benefits: Caulerpa contains proteins, fiber, minerals, vitamins, polyunsaturated fatty acids, and bioactive anti-oxidants. The consumption of these seaweeds is well established in local traditions and, for this reason, several seaweed farms have been established, or are under assessment, with a view to providing additional sources of income for local communities and to secure their livelihoods. Currently Caulerpa species are mostly collected from the wild and sold on the markets. However, farms can use a range of culture techniques such as bottom planting, off-bottom culture, floating long lines, or land-based raceways. This paper presents an overview of the traditional consumption and nutritional values of Caulerpa in the Indo-Pacific region and the different farming methods used for Caulerpa culture.

Rapid identification of osmolytes in tropical microalgae and cyanobacteria by 1H HR-MAS NMR spectroscopy

In this study, we report the chemical characterization of 47 tropical microalgae and cyanobacteria by HR-MAS. The generated data confirm the interest of HR-MAS as a rapid screening technique with the major advantage of its easiness. The sample is used as powder of freeze-dried microalgae without any extraction process before acquisition. The spectral fingerprints of strains are then tested as variables for a chemotaxonomy study to discriminate cyanobacteria and dinoflagellates. The individual factor map generated by PCA analysis succeeds in separating the two groups, essentially thanks to the presence of specific carbohydrates. Furthermore, more resolved signals enable to identify many osmolytes. More precisely the characteristics δ of 2-O-alpha-D-glucosylglycerol (GG) are observed in all 21 h-MAS spectra of tropical cyanobacteria. After specific extraction, complementary analysis by 1D and 2D-NMR spectroscopies validates the identification of this osmolyte.

Chemogeography of the red macroalgae Asparagopsis : metabolomics, bioactivity, and relation to invasiveness

IntroductionThe Latitudinal Gradient Hypothesis (LGH) foresees that specialized metabolites are overexpressed under low latitudes, where organisms are subjected to higher herbivory pressure. The widespread macroalga Asparagopsis taxiformis is composed of six distinct genetic lineages, some of them being introduced in many regions.ObjectivesTo study (i) metabolic fingerprints of the macroalga and (ii) its bioactivity in space and time, both as proxies of its investment in defensive traits, in order to assess links between bioactivities and metabotypes with macroalgal invasiveness.Methods289 macroalgal individuals, from four tropical and three temperate regions, were analyzed using untargeted metabolomics and the standardized Microtox® assay.ResultsMetabotypes showed a low divergence between tropical and temperate populations, while bioactivities were higher in temperate populations. However, these phenotypes varied significantly in time, with a higher variability in tropical regions. Bioactivities were high and stable in temperate regions, whereas they were low and much variable in tropical regions. Although the introduced lineage two exhibited the highest bioactivities, this lineage could also present variable proliferation fates.ConclusionThe metabolomic approach partly discriminates macroalgal populations from various geographic origins. The production of chemical defenses assessed by the bioactivity assay does not match the macroalgal genetic lineage and seems more driven by the environment. The higher content of chemical defenses in temperate versus tropical populations is not in accordance with the LGH and cannot be related to the invasiveness of the macroalgae.

Macroalgae as a tool for assessing the ecological status of coral reefs under the Water Framework Directive: A case study on the reef flats of La Réunion (Indian Ocean)

The monitoring of macroalgae is required by the Water Framework Directive (WFD) to achieve good ecological status for coastal waters and specific questions arise for tropical ecosystems belonging to the outermost European regions. To assess the suitability of macroalgae as a biological quality indicator for La Réunion reef flats (France), we performed multivariate analyses linking the abundance and composition of macroalgae to water physico-chemistry. Three hydrological groups of stations were identified according to dissolved inorganic nitrogen (DIN) concentrations and DIN/PO4 ratios. Some indicator species were found at the N-enriched stations (Bryopsis pennata, Caulerpa lamourouxii, Chaetomoropha vieillardii, Derbesia sp., Blennothrix lyngbyacea, Sphacelaria tribuloides), and others at the non-impacted stations (Anabaena sp1, Blennothrix glutinosa, Codium arabicum, Neomeris vanbosseae). Another key result was the significant increase in red algal cover at the most N-enriched station. Our findings are discussed in the context of the application of the WFD in the outermost French regions.

Exploring the chemodiversity of tropical microalgae for the discovery of natural antifouling compounds

Marine microalgae and cyanobacteria have largely been studied for their biotechnological potential and proved their ability to produce a wide array of bioactive molecules. We investigated the antifouling potential of unexplored benthic tropical microalgae using anti-adhesion and toxicity bioassays against two major micro- and ma crobiofoulers, namely bacteria and barnacles. Fifty strains belonging to six phyla [Cyanobacteria, Miozoa (Dinoflagellata), Bacillariophyta, Cryptophyta, Rhodophyta and Haptophyta] were isolated from southwestern Islands of the Indian Ocean. They were chosen in order to represent as much as possible the huge biodiversity of such a rich tropical ecosystem. The associated chemodiversity was highlighted by both NMR- and LC-MS-based metabolomics. The screening of 84 algal fractions revealed that the anti-adhesion activity was concentrated in methanolic ones (i.e. 93% of all active fractions). Our results confirmed that microalgae constitute a promising source of natural antimicrofoulants as 17 out of the 30 active fractions showed high or very high capacity to inhibit the adhesion of three biofilm-forming marine bacteria. Dinoflagellate-derived fractions were the most active, both in terms of number and intensity. However, dinoflagellates were also more toxic and may not be suitable as a source of environmentally friendly antifouling compounds, in contrast to diatoms, e.g. Navicula mollis. The latter and two dinoflagellates of the genus Amphidinium also had interesting anti-settlement activities while being moderately toxic to barnacle larvae. Our approach, combining the bioprospecting of a large number of tropical microalgae for their anti-settlement potential and metabolomics analyses, constituted a first step towards the discovery of alternative ecofriendly antifoulants.