Potentiality of Using Spreading Sargassum Species From Indonesia as an Interesting Source of Antibacterial and Radical Scavenging Compounds: a Preliminary Study

As an archipelagic country with 95,181 km long coastline, Indonesia has great potential as the producer of seaweeds. The diverse phyla of marine macroalgae (red, brown and green seaweeds) are known to produce molecules which are attractive for diverse industries. Applications of algal products range from simple biomass production for food, feed and fuels to valuable products such as sugar polymers, cosmetics, pharmaceuticals, pigments, and food supplements. Seaweeds also have the potential to be used as a source of new bioactive for human, animal or plant health, as well as a source of new synthons and biocatalysts in sustainable chemistry (Bourgougnon and Stiger-Pouvreau, 2011). In this paper, among species of economic value we focus on brown seaweeds belonging to family Sargassaceae and genus Sargassum spreading along Indonesian coasts. Members of this genus are especially abundant in tropical and subtropical regions (Zemke-White and Ohno, 1999). The purpose of this study is to analyze the antibacterial and antioxidant activity of three species of Sargassum, i.e. S. echinocarpum, S. duplicatum and S. polycystum. Both polar and non-polar extracts have been prepared from those three species. In vitro antibacterial activities of extracts were evaluated against Gram-positive bacteria Staphylococcus aureus and Gram-negative bacteria Escherichia coli. Results indicated all the three species tested showed an antibacterial activity. The most effective antibacterial activity against S. aerous was from S. echinocarpum with ethil asetat, inhibition zone 1.13 ± 0.25 mm; S. duplicatum with N-Hexane was most effective against E. coli, 1.20 ± 0.28 mm

Topological entropy of a stiff ring polymer and its connection to DNA knots

We discuss the entropy of a circular polymer under a topological constraint. We call it the {\it topological entropy} of the polymer, in short. A ring polymer does not change its topology (knot type) under any thermal fluctuations. Through numerical simulations using some knot invariants, we show that the topological entropy of a stiff ring polymer with a fixed knot is described by a scaling formula as a function of the thickness and length of the circular chain. The result is consistent with the viewpoint that for stiff polymers such as DNAs, the length and diameter of the chains should play a central role in their statistical and dynamical properties. Furthermore, we show that the new formula extends a known theoretical formula for DNA knots.Comment: 14pages,11figure

Simple and Rapid Voltammetric Method Using a Gold Microwire Electrode to Measure Inorganic Arsenic in Holopelagic <i>Sargassum</i> (Fucales, Phaeophyceae)

The valorization of massive strandings of holopelagic Sargassum spp. is strongly limited by high levels of inorganic arsenic (Asi) that are potentially above the limit of current regulations. Monitoring Asi in algal biomass is currently achieved using standard chromatographic separation followed by spectroscopic detection. Here, we propose an alternative simpler procedure based on the extraction of Asi from the freeze-dried algal powder in deionized water and the electroanalytical detection of the diluted extract at a gold-microwire electrode. The protocol was optimized both in terms of extraction (powder/water ratio, extraction time, temperature) and electrolyte used for the voltammetric detection. Two electrolytes were tested: one composed of citric acid, sulfamic acid and KCl (pH 2.0) and another composed of an acetate buffer (pH 4.7) and NaCl. We demonstrate here that Asi determination is possible with the first electrolyte but it is necessary to deal with a relative unstable signal. Measurement of Asi was best achieved with the second electrolyte (acetate buffer and NaCl) with the following optimized electrochemical conditions: deposition potential of −1.2 V, deposition time of 30 seconds and linear scan voltammetry. Voltammetric results were then compared to a reference method (HPLC-ICP-MS) using different morphotypes of holopelagic Sargassum spp. (S. natans VIII, S. natans I and S. fluitans III), using commercial extracts of brown seaweeds and using a Hijiki certified reference material. Very good agreement was obtained between our novel method and HPLC-ICP-MS. Both methods show that inorganic arsenic is almost entirely present as As(V) in Sargassum spp. extracts

Analysis of sexual phenotype and prezygotic fertility in natural populations of Fucus spiralis, F. vesiculosus (Fucaceae, Phaeophyceae) and their putative hybrids

In the genus Fucus, the character dioecy/hermaphroditism has undergone multiple state changes and hybridization is possible between taxa with contrasting mating systems, e.g. between the dioecious Fucus vesiculosus and the hermaphrodite F. spiralis. In the context of mating system evolution, we evaluated the potential consequences of hybridization by studying the variation in sexual phenotype and prezygotic fertility. Firstly, as a result of hybridization between the two sexual systems, gender variation may arise depending on the relative importance of genes with large versus small phenotypic effects. We thus qualitatively examined the extent of gender variation within and among individual hybrids in comparison with both parental species. Secondly, if hybridization breaks up co-adapted gene complexes, hybrid fertility may be reduced in comparison with both parental species. Therefore, we also quantified male and female prezygotic fertility in parental species and their hybrids in order to test for reduction in hybrid fitness. A total of 89 sexually mature individuals (20 F. spiralis, 40 F. vesiculosus, 10 hermaphrodite hybrids and 19 dioecious hybrids) were sampled in two geographically distant regions (France and Portugal) and six conceptacles per individual were observed. Within-individual variation was very restricted qualitatively – only one hybrid carried a conceptacle with a different sexual phenotype from the five others – as well as quantitatively. This suggests a simple genetic system for sex determination involving a few genes with major effects. In addition, analyses showed no significant decrease in hybrid fertility compared with parental species. Moreover, hybrids exhibited all sexual phenotypes, suggesting several generations of hybridization and backcrossing and, therefore, that hybrids are reproductively successful. Finally, the occurrence of sterile paraphyses in female and hermaphrodite individuals was interpreted as a relic of male function and suggests that, as in higher plants, evolution from hermaphroditism to dioecy may be the most parsimonious pathway

Taxonomic revison of Sargassum (Fucales, Phaeophyceae) from French Polynesia based on morphological and molecular analyses

An assessment of Sargassum in French Polynesia was done through the critical revision of the literature, type specimens, and specimens from type localities. Sargassum samples were newly collected, and four morphotypes were identified on the basis of morphological characters. Molecular analysis of the nuclear ITS2, chloroplastic partial rbcLS, and mitochondrial cox3 markers generated two clades and confirmed the recent divergence suspected between closely related species. Although 18 different epithets have been attributed to French Polynesian Sargassum since 1828, only three species are considered valid in this study. Most of these species were transferred to S. pacificum Bory, the only species present in the Society Archipelago, while S. obtusifolium J. Agardh was restricted to the Austral Archipelago, and S. echinocarpum J. Agardh was confirmed for the Austral and Gambier Archipelagos. A morphological identification key is provided, along with descriptions and illustrations for each polymorphic species. Moreover, the study of several regional collections underlined similar and low specific diversity among Sargassum populations in the southeastern Pacific. As a result of this study, we propose that S. bacciferum J. Agardh var. latiuscula Grunow, S. bisserula f. pacifica Grunow, S. boraborense (Grunow) Setch., S. mangarevense (Grunow) Setch., S. sociale (Grunow) Setch., and S. tahitense Grunow be considered as heterotypic synonyms of S. pacificum. Sargassum skottsbergii Sjostedt, S. hawaiiensis Doty et Newhouse, S. divaricatum var. chilensis Grunow, S. obtusifolium J. Agardh f. chamberlainii Grunow, and S. obtusifolium J. Agardh f. lendigeroides Grunow are further regarded as heterotypic synonyms of S. obtusifolium

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

International audienceMarine 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

Discrimination of allied species within the genus Turbinaria (Fucales, Phaeophyceae) using HRMAS NMR spectroscopy

A novel chemotaxonomical method based on ID H-1 HRMAS NMR spectroscopy is being tested for taxonomical purposes. This powerful technique allowed us to discriminate between specimens belonging to two sister species of Turbinaria, which are difficult to tell apart using only morphological characters. Based on spectra analysis, the results allowed us to successfully group the specimens according to their species. Thus, the efficiency of HRMAS NMR spectroscopy for the discrimination of algal species and for the pre-screening of potential chemomarkers is demonstrated

Anti-microfouling activity of lipidic metabolites from the invasive brown alga Sargassum muticum (Yendo) Fensholt

International audienceThe purification of the chloroform extract from the brown invasive macroalga Sargassum muticum, through a series of chromatographic separations, yielded 12 fractions that were tested against strains of bacteria, microalgae, and fungi involved in marine biofilm formation. The chemical composition of four (a, c, g, and k) out of the six fractions that exhibited anti-microfouling activity was investigated. Fraction a contained saturated and unsaturated linear hydrocarbons (C12-C27). Arachidonic acid was identified as the major metabolite in fraction c whereas fraction g contained mainly palmitic, linolenic, and palmitoleic acids. Fraction k was submitted to further purification yielding the fraction kAcaF1e that was composed of galactoglycerolipids, active against the growth of two of the four bacterial strains (Shewanella putrefaciens and Polaribacter irgensii) and all tested fungi. These promising results, in particular the isolation and the activity of galactoglycerolipids, attest the potential of the huge biomass of S. muticum as a source of new environmentally friendly antifouling compounds

Anti-microfouling activity of lipidic metabolites from the invasive brown alga Sargassum muticum (Yendo) Fensholt

The purification of the chloroform extract from the brown invasive macroalga Sargassum muticum, through a series of chromatographic separations, yielded 12 fractions that were tested against strains of bacteria, microalgae, and fungi involved in marine biofilm formation. The chemical composition of four (a, c, g, and k) out of the six fractions that exhibited anti-microfouling activity was investigated. Fraction a contained saturated and unsaturated linear hydrocarbons (C 12-C 27). Arachidonic acid was identified as the major metabolite in fraction c whereas fraction g contained mainly palmitic, linolenic, and palmitoleic acids. Fraction k was submitted to further purification yielding the fraction kAcaF1e that was composed of galactoglycerolipids, active against the growth of two of the four bacterial strains (Shewanella putrefaciens and Polaribacter irgensii) and all tested fungi. These promising results, in particular the isolation and the activity of galactoglycerolipids, attest the potential of the huge biomass of S. muticum as a source of new environmentally friendly antifouling compounds. © Springer Science + Business Media, LLC 2009