Eric Deslandes

Interspecific and temporal variation in phlorotannin levels in an assemblage of brown algae

Abstract We report here on a survey of phenolic contents in all seaweeds forming belts on a sheltered rocky shore in Brittany (France). Eight species of brown algae (7 Fucales and 1 Laminariales) were investigated over a 14-month period. Levels of phenolic compounds in members of the Fucales were generally above 2% DW and exceeded those found in the Laminariales by a factor of ten. The highest contents were found in species growing at mid-tide level, with a decrease above and below this shore level. There was a seasonal pattern, with a summer maximum for the Fucales and winter maximum for a member of the Laminariales.

Intra-thallus phlorotannin content and antioxidant activity in Phaeophyceae of temperate waters

Abstract This study focuses on the intra-thallus variation in phlorotannin content and antioxidant activity in temperate brown seaweeds. Two species of Fucales (Ascophyllum nodosum and Sargassum muticum) and two species of Laminariales (Laminaria digitata and L. hyperborea) were collected from the shoreline of Brittany (France). Both Fucales contained high phenolic levels along their thallus (ca. 5% DW in A. nodosum and 6% DW in S. muticum). No significant differences were found between vegetative and reproductive parts of A. nodosum. In contrast, intra-thallus and inter-specific variations were observed in phenolic contents of the two species of Laminariales studied. In L. digitata, phenolic content was about 0.2% DW, with a maximum in the holdfast, whereas in L. hyperborea, it averaged about 2.6% DW, with the highest value measured in the basal part of the old blade. In both species, phlorotannin contents were lower in the meristematic region. Intra-thallus variations of the antioxidant activity measured by the DPPH (2,2-diphenyl-1-picrylhydrazyl) method were also detected. Antioxidant activity was correlated to the phenol contents of the different parts of thalli in three species. In L. digitata, no activity was found because of low phenol levels. The observed variations in both the antioxidant activity and the phenol content could result from qualitative features of the phenolic pool.

Phenolic contents of two brown algae, Turbinaria ornata and Sargassum mangarevense on Tahiti (French Polynesia): interspecific, ontogenic and spatio-temporal variations

Abstract To elucidate the possible implications of phenolic content in survival strategies of two tropical brown fucaleans, Turbinaria ornata and Sargassum mangarevense, we determined total phenolic contents in relation to ontogenic stages, and then followed spatio-temporal variations. Samples were collected at different sites and seasons. Both species exhibited low phenolic contents with, however, some differences: levels were higher in the algae from grazer- and nutrient-rich sites, and during the austral summer. Moreover, adults produced more phenolic compounds than immature stages. In addition, Turbinaria ornata had higher levels than Sargassum mangarevense. Parent thalli may exert an indirect protection of easily-grazed recruits which settle in close vicinity. The differences between species in protection of recruits would, therefore, derive from the respective species morphologies. A mechanical protection can be hypothesized in S. mangarevense because of its soft flexible thallus: plants can sweep around their base and, therefore, would need to produce less phenolics as a repellent than Turbinaria. On the other hand, due to its relatively tough texture, together with its upright-thallus, Turbinaria has a greater need to protect recruits by chemicals. The low phenolic content observed from thalli collected at the outer barrier reef may be explained by an exudation of phenolics after dessication.

Isethionic Acid and Floridoside Isolated from the Red Alga, Grateloupia turuturu, Inhibit Settlement of Balanus amphitrite Cyprid Larvae

Isethionic acid (2-hydroxyethane sulfonic acid) and floridoside (2-O-α-D-galactopyranosylglycerol) were extracted from the red alga, Grateloupia turuturu, and tested for anti-settlement activity against cyprid larvae of the tropical barnacle, Balanus amphitrite and for their toxicity to nauplius larvae. Isethionic acid was active for anti-settlement but had the disadvantage of being toxic to nauplius larvae. Floridoside was a potent inhibitor of cyprid settlement at non-toxic concentrations to nauplii (0.01 mg ml−1).

Co-occurrence and antioxidant activities of fucol and fucophlorethol classes of polymeric phenols in Fucus spiralis

Abstract In a study of structural diversity in the total pool of phlorotannins in brown algae, we have shown, for the first time in any alga (by means of solvent partition and NMR experiments), that Fucus spiralis has simultaneous production of two types of polymeric phlorotannins of the fucol and fucophlorethol classes, respectively. These components exhibited a greater antioxidant activity than ascorbic acid and the monomer phloroglucinol, a constitutive of the polymeric phlorotannins. No significant differences in antioxidant activity were observed between fucol and fucophlorethol.

Anti-microfouling activities in extracts of two invasive algae: Grateloupia turuturu and Sargassum muticum

Marine macroalgae are particularly prone to epiphytism. The colonisation of their surface may lead to severe perturbations and sometimes to the death of the host. To protect themselves against settling and/or competing organisms, many algae have developed defences against fouling by producing a wide variety of chemically active metabolites. The goal of this study was to investigate potential anti-microfouling activities of two introduced algal species from the Brittany coast (France), Sargassum muticum (Phaeophyceae) and Grateloupia turuturu (Rhodophyceae). Thus, a complete study of the antimicrobial activities of extracts (aqueous, acetone, chloroform, dichloromethane, diethyl-ether, ethyl acetate, ethanol 96°, hexane and methanol) from S. muticum and G. turuturu against marine fouling bacteria (5 strains), fungi (5 strains) and biofilm-associated microphytobenthic strains (5) were performed. The most active extract of G. turuturu was the dichloromethane fraction, while the chloroform extract from S. muticum showed some good results. Our data suggest that these macroalgae can provide useful compounds or templates for industrial anti-microfouling applications.

Preliminary study of the in vitro antiproliferative effect of a hydroethanolic extract from the subtropical seaweed Turbinaria ornata (Turner J. Agardh) on a human non-small-cell bronchopulmonary carcinoma line (NSCLC-N6).

An unusual sulfated fucan-like polysaccharidecontaining aminosugar constituent was isolated fromthe brown Fucales, Turbinaria ornata. Itsantiproliferative effect on asynchronous cells of ahuman non-small-cell bronchopulmonary carcinoma line(NSCLC-N6) was studied in vitro. The kinetics ofcell growth further to the continuous exposure ofcells to T. ornata extract was investigated andthe changes in the cell cycle were observed usingflow-cytometry. Cell growth appeared to be inhibitedin the G1 phase. Altogether our observations suggesta triggering of the terminal differentiation ofcancerous cells by this fucan-like polysaccharide.

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.

Complete 1H and 13C spectral assignment of floridoside.

Floridoside (2-O-alpha-D-galactopyranosylglycerol) was extracted from the red marine alga Rhodymenia palmata, and purified by ion-exchange chromatography: 1D and 2D NMR spectroscopy experiments were used to unambiguously assign the complete 1H and 13C spectra.

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.