American Journal of Innovative Research and Applied Sciences. ISSN 2429-5396 I www.american-jiras.com                             ORIGINAL ARTICLE |Martial Hernas Rakotoarisoa 1*|Taratra Andrea Fenoradosoa 1 | Fatah Abdoul 1 | Guillaume Pierre 2 | Julio Hervé Andriamadio 1| Cédric Delattre 2 | Philippe Michaud 2 | and | Lehimena Clément 1| 1. University of Antsiranana (UNA) | Faculty of Science | Laboratory of Chemistry of Natural Substances and Environmental Sciences | Antsiranana | Madagascar | 2. Clermont Auvergne University, Blaise Pascal University | Pascal Institute | Unit or laboratory CNRS, UMR 6602, IP, F-63178 Aubière| Clermont-Ferrand | France | 2. MATERIELS AND METHODES 2.1 Plante material Haliptilon subulatum were collected at Complex Nosy Hara in the North region of Madagascar in Mars 2012. Haliptilon subulatum were cleaned three times with water of tap in order to remove salts, sands as well as the remains of the corals and dried in oven at 60 °C during 3j. Finally, dried Haliptilon subulatum were preserved in a well closed plastic box.2.2 Extraction and purificationExtraction of polysaccharides was carried out in hot water. Dry powder of Haliptilon subulatum (25 g) was dispersed in distilled water (600 mL) at 90 °C during 2 H under agitation. Then, the solution was filtered and centrifugated (6 000 g, 30 min). The polysaccharide in the obtained solution were precipitated by addition of 3 volumes of cold ethanol (96 %) and washed with acetone. The polysaccharide was collected by filtration and washed with methanol (this stage is repeated twice). The polysaccharide was stored in a desiccator under vacuum in order to preventing moisture from the air.2.3 Composition analysisTotal neutral sugar content was determined by the reaction with resorcinol in presence of sulfuric acid using glucose as a standard [14]. The total uronic acid content was colorimetrically determined by the m-hydroxydipheny assay using galacturonic acid as standard, [15] adapted from Filisetti-Cozzy et al., (1991) [16]. Protein contenant was determined by the copper sulfate assay using bovine serum albumin as a standard, Biuret methode adapted from Lowry et al., (1951) [17].2.4 Analysis of monosaccharides composition by HPAEC Polysaccharides from Haliptilon subulatum (10 mg) dissolved in 4 M TFA (1 mL) were heated at 100° C during 8 h. The hydrolysates were neutralized with ammonia solution (4 M).Monosaccharide composition of polysaccharide extracted from Haliptilon subulatum was evaluated by High Pressure Anion Exchange Chromatography (HPAEC) on an ICS 3000 (Dionex, USA) equipped with pulsed amperometric detection and AS 50 autosampler. It was assembled with a guard CarboPac PA1-column (4 × 50 mm) and analytical CarboPac PA1-column (4 × 250 mm). Samples (10 mg/mL) were filtered using 0.2 μm membrane filter and injection volume was fixed at 25 μL. Before each injection, columns were equilibrated by running during 15 min with 18 mM NaOH. Samples were eluted isocratically with 18 mM NaOH for 30 min, followed by a linear gradient between 0 to 1 M sodium acetate in 200 mM NaOH for 20 min to elute acidic monosaccharides. Run was followed by 15 min washing with 200 mM NaOH.The eluent flow rate was kept constant at 1 mL/min. Columns were thermostated at 25°C. Data were collected and analyzed with Dionex Chromeleon 6.80 software (Sunnyvale, USA).2.5 Spectroscopic analysis from Haliptilon subulatumFourier-Transform Infrared (FT-IR) measurements were carried out using a Nicolet 380 FT-IR instrument (Thermoelectron Corporation, France). The samples were deposed to from a pellet to KBr (1-3 mg of dried polysaccharides from Haliptilon subulatum were dispersed into 100 mg of KBr). The IR spectra were recorded and at room temperature (referenced against air) with the wave number range of 400-4000 cm-1. Spectra were analyzed with logiciel Omnic 7.3 software (ThermoElectron Corporation).2.6 Determination of molecular weight by using SEC/MALLS analysisAverage molecular weights and molecular weight distributions of polysaccharides from Haliptilon subulatum were determined by high pressure size exclusion chromatography (HPSEC) with on line multi-angle laser light scattering (MALLS) filled with a K5 cell (50 μL) and two detectors: a differential refractive index (DRI) and a He–Ne laser (λ = 690 nm). Columns [OHPAK SB-G guard column, OHPAK SB806, 804 and 803 HQ columns (Shodex)] were eluted with NaNO3 0.1 M at 0.6 mL/min. Solvent was filtered through 0.1 μm filter unit (Millipore), degassed and filtered through a 0.45 μm filter upstream column. The sample was sample was injected at 5 g/L through a 100 μl full loop with a flow rate of 0.4 mL/min. The collected data were analyzed using the Astra 4.90.08 software package and a dn/dc of 0.15.2.7 Antioxidant assays of poly- and oligosaccharides from Haliptilon subulatumAll assays were done about several concentration of poly-and oligosaccharides (from 0 to 10 g/L) dissolved in distillated water. Absorbances were measured using à Shimadzu UV-1700 spectrophotometer.2.7.1 Scavenging activity against DPPH radicalThe measurement of the anti-DPPH activity of polysaccharides and oligosaccharides from Haliptilon subulatum was evaluated 2, 2' -diphényl-1-picrylhydrazyle (DPPH) procedure as described by add name of the author Yamaguchi et al., (1998) [18]. One mL of solutions of the fraction (poly-oligosaccharide) at various concentrations (0 to 10 g/L) added into 1 mL solution of DPPH (0.1 mM in ethanol). After homogenization with the vortex, the solution was stirred and incubated 30 mn at room temperature (25 °C) in dark before to measure its absorbances at 517 nm. The DPPH inhibition (%) was estimated by using the following aquation (1):Inhibition of radical DPPH (%) = (1- (Asample/Acontrol)) x 100                   (1)Where:  Asample= Absorbance 517 nm of the fraction sample + DPPH (0.1 mM in ethanol) and Acontrol= Absorbance at 517 nm of a mixture of distilled water 1mL + 1mL of DPPH (0.1 mM in ethanol).The DPPH radical scavenging efficiency was expressed as IC50 which is the concentration of polysaccharide and oligosaccharide at which the scavenging rate reached 50 %2.7.2 Scavenging activity against hydroxyl radicalThe scavenging activity against hydroxyl radical of the polysaccharides and oligosaccharides from Haliptilon subulatum was quantified using hydroxyl radical procedure as adapted from Luo et al., (2010) [19]. 0, 2 mL of solutions of fractions (polysaccharide and oligosaccharide) at various concentrations (0 to 10 g/L) was added into 0, 2 mL of an aqueous solution of FeSO4 at 5 mM. After stirring, 0, 2 mL of an aqueous solution of H2O2 at 1 % (v/v) was added to the mixture. The solution was stirred and incubated at room temperature during 60 min and 1 mL of distillated water was added. The absorbance was then measured at 510 nm. The percentage hydroxy radical inhibition (%) was calculated by using the following equation (2):Inhibition of the radical hydroxyl (%) = ((Acontrol- Asample)/Acontrol)) x 100          (2)Where Asample and Acontrol are the absorbances at 510 nm of the sample (poly- or oligosaccharides) (0- 10 g/L) or 0, 2 mL of distillated water with 0,3 mL of a solution (v/v) of FeSO4 (5 mM)/ H2O2 (1 %). The hydroxyl radical scavenging efficiency was expressed as IC50 which is the concentration of polysaccharide and oligosaccharide at which the scavenging rate reached 50 %.  2.7.3 Scavenging activity against superoxide anionThe scavenging activity against superoxide anion was realized using the protocol by Wang et al. (2007) [20]. 0, 42 mL of solution polysaccharide and oligosaccharide (0 to 10 g/L) were mixed with 0, 45 mL of Tris-HCl (50 mM, pH=8, 2). This mixture was incubated 20 min at temperature 20 °C. After that, 30 µL of pyrogallol solution (5 mM in distillated water) were added and the mixture was stirred. After incubation for 5 min, 0, 1 mL of ascorbic acid solution (5 % w/v) was added to stop the reaction and the absorbance was measured at 325 nm.The percentage of the anti-superoxide anion radical activity was calculated according to the equation (3): Inhibition du radical superoxyde anion (%) = ((Acontrol- Asample)/Acontrol)) x 100     (3)Where Asample and Acontrol are the absorbances at 325 nm of 0, 420 mL of the sample (0-10 g/L) or 0, 420 mL of distilled water with 0, 450 mL of Tris-HCl (pH= 8, 2; 50 mM)/ 30 µL of pyrogallol (5 mM/ 0, 1 mL of ascorbic acid (5 %).  The superoxide anion radical scavenging efficiency was expressed as IC50 which is the concentration of polysaccharide and oligosaccharide which the scavenging rate reached 50 %.2.7.4 Reducing power The reducing power of poly- and oligosaccharides from Haliptilon subulatum was estimated according to protocol published by Yan et al., (2005) [21]. 0, 10 mL of solution poly- and oligosaccharide (0 to 10g/L) was mixed with 0, 250 mL of phosphate sodium buffer (0, 2M, pH= 6, 6) and 0, 25 mL of potassium ferricyanide (1 %w/v).  This mixture was incubated at 50 °C during 20 min and placed during 15 min in an ice bath. Then, 0, 25 mL of trichloroacetic acid (10 % w/v) was added and the mix was stirred for 1 min. The mixture was centrifuged for 10 min at 5000 rpm at 25 °C. Finally, 0, 250 mL of supernatant was mixed with 0, 250 mL of distilled water and 0, 050 mL of FeCl3 (0,1 %, m/v in distilled water). After 5 min, at room temperature, the absorbance was read at 700 nm. 3. RESULTS AND DISCUSSION3.1 Chemical Composition In order to extract and identify the nature of matric polysaccharides from Haliptilon subulatum, we have adapted from the literature available for the extractions of polysaccharides from red algae [3, 22, 23]. The extraction and purification of matric polysaccharides from Haliptilon subulatum using ethanol and acetone. The product obtained is qualified as depigmented. The extraction yield was estimated at 10-20 % based on dried polysaccharide powder. Note that during the extraction process was carried out in mediums aqueous and the extraction with pH alkaline could promote the  formation of 3.6-anhydrogalactose to the detriment of galactoses linked in 4 and of the polysaccharide sulphated in 6. The extraction at acid pH could be done origin of partial depolymerization.  According to literature, this extraction yield is comparable with the 13% described during the extraction of matrix polysaccharides from Grateloupia indica (Halymeniales) and the 16% for the extraction of Halymenia durvillei (Halymeniales) at neutral pH for 4 hours at 90 ° C [23, 24]. The salt levels of Haliptilon subulatum estimated by conductivity are 31.6 mg / g at 60.8 µs /cm. Chemical analysis (colorimetric) of this matric polysaccharide d’ Haliptilon subulatum revealed that it is composed 40.96 % of total sugar, 39.96 % of neutral oses and 8.39 % of acidic oses and with low protein contents (6, 83 %). It is important to emphasize that this result in neutral ose is in agreement with neutral ose of Halymenia durvillei polysaccharide extracted with water evaluated 40 % (m / m) those [24] and what which differs in acid and protein levels. The level of 3,6-anhydrogalactopyranose by colorimetric assay showed that the extracellular polysaccharide of Haliptilon subulatum is composed of 1.32 % (w / w) 3,6-anhydrogalactopyranose. This result is in agreement with the published bibliographic data [25] of 1.06 % (m / m) of 3,6-anhydrogalactopyranose from Asparagopsis aramata assayed by gas chromatography and lower than the written literature by Garon Lardiere, (2004) [24] of 2.4 % (m / m) of 3,6-anhydrogalactopyranose from Halymenia durvillei. The sulphate level was carried out according to the turbidimetric method. The sulfation of the polymer evaluated at 13.5 % by mass. This result is significantly superior to the sullfate (5 %) of the matrix polysaccharide of Porphyridium cruentum [10] but it is lower than that published by Fenoradosoa et al., 2009 [24] of Halymenia durvillei polysaccharides (44 %).3.2 Monosaccharide compositionThe last decades, lots of studies have been investigated on the analysis of algae polysaccharides reed and in particular those derived from red algae (Rhodophyceae) [10]. Nevertheless, no studies deal with polysaccharide of the Haliptilon subulatum despite the abundance of this species in tropical areas and and especially in northern Madagascar. The identification of the monosaccharides composition of the polysaccharide from Haliptilon subulatum was investigated by HPAEC after acid hydrolysis (Tableau 1). It was mainly composed of galactose (88, 4 %) and et and has 4 other very minor: xyloses (4, 3 %); glucoses (4, 0 %); fucoses (1, 5 %); arabinoses (1, 0 %) et d’une trace d’acide glucuronique (0, 8 %). This analysis allowed us to identify and simultaneously quantify the monosaccharides constituting the polysaccharide of Haliptilon Subulatum. It is therefore a galactan-type polysaccharide having 88.4 mol % of galactose with a ratio of 13. 92.This monosaccharides composition was consistent with published works where polysaccharide from Halymenia durvillei generally contained: galactose, glucose, xylose, arabinose, fucose and glucuronique acid as main monosaccharides [24]. Moreover, the monosaccharides ratios were strongly influenced not only by extraction processes but also by rain, temperature, and its humidity rate [26]. In comparison to the other monosaccharides composition of polysaccharide from Haliptilon Subulatum contains higher quantity of galactose than the polysaccharide from Halymenia durvillei (54, 2 %) and lower quantities of glucose, xylose, arabinose, fucose et une trace d'acide glucuronique [24]. In other cases, the matric polysaccharides of Porphyridium cruentum and Asparagosis aramata contain 19 % and 37 % by mass of galactose, respectively [27, 25]. Of these three species, the polysaccharide extract of Haliptilon subulatum was found to be very rich in galactose.Tableau 1: Characterisation polysaccharide extracted at room temperature from Haliptilon subulatumMw (g/mol)aMn (g/mol)bIpcMonosaccharides (mol %)dGalXylGlcFucArbGlucA213 300133 3001.60288.4±13.924.3±16.864.0±14.871.5±5.681.0±10.800.8±37.97a Mw: molecular weight estimated by SEC MALLSb Mn: Number average molecular weight estimated by SEC MALLSc Ip: index of polydispersity estimated by SEC MALLSd Monosaccharides composition was estimated by HPAEC, Gal: Galactose; Xyl: Xylose; Glc: Glucose; Fuc: Fucose; Arb: Arabinose and GlucA: Glucuronic acid.3.3 Spectroscopic analysis The polysaccharide extracted from the Haliptilon subulatum was analysed by FT-IR spectroscopy (Figure 1).  As observed in the spectrum, characteristic bands were assigned. The band 3418 cm-1 between the [3700- 3300] cm-1 is attributed to the hydroxyl (O-H) stretching vibration of polysaccharides as well as water adsorption [25]. The bande observed at 2920 cm-1 is attributed to the asymmetric vibration of C-H glycosidic residus by this band is generally weaker in intensity and quite wide. The band intense and relatively thin profiling around 1640 cm-1 is attributed to the symmetrical angular deformation of the C = O bond [25, 28]. Absorption bands around 1613 cm-1 and 1418 cm-1 is resulting from the vibration deformation of C-OH function with the contribution of symmetrical vibration elongation of carboxylate group (-COO-) [29, 30] were band intense located at 1250 cm-1 corresponded more especially to the stretching vibration elongation asymmetric of O = S = O bonds of the ester sulfate groups [31, 32]. Thus, the signal observed around [1160-1140] cm-1 are attributed to C-C bond and of C-O the pyranosic ring. The symmetrical elongation vibration of these same bonds absorbs around 1030 cm-1. This is probably due to interference from the elongating vibrations of the C-O and C-O-H bonds which absorb at 1050 cm-1. Finally, the band located in the zone [1000-800] cm-1 is corresponded generally to the position of certain sulphate groups and of 3,6 anhydrogalactose residues of elongation vibrations C-O-S links. Indeed, the band around [840-805] cm-1 which are characteristic of the sulphated galactoses in 4 and in 2 or in 6, see in 6 and in 2. The spectrum majority and unique around 845cm-1 is characteristic of the presence of an axial secondary sulfate ester placed in position 4 on the β-(1,3)-D-galactopyranose unit [33]. In our case, there is a single and predominant band around 834 cm-1 which confirms the presence of sulphates in position 4 of β-(1,3)-D-galactopyranose unit. Bands between 930-1240 cm-1 are characteristic of bond elongation vibration C-O of a 3,6-anhydrogalactose [34].Figure 1: Spectre Infra-Rouge de la fraction polysaccharidique extraite de l’algae Haliptilon subulatum.3.5 Molecular weight analysis The molecular weight (Mw) of polysaccharide and oligosaccharide extracted from Haliptilon subulatum was evaluated by SEC MALLS analysis.  As mentioned in Tableau 1, the Mw of this hydrocolloid was estimated at 213 500 g/mol with polydispersity index of 1.6 which confirmed the presence of high molecular homogenous polysaccharides structure in figure 2. By comparaison, the high molecular weight of the galactan extracted from Haliptilon subulatum are in superior with those of  and -carrageenans estimated lie between 300,000 to 400,000 g / mol [35, 36, 37] and λ-carrageenans, the molar masses described are rather around 600,000 g / mol to 700,000 g / mol [35, 38]. In terms of the polydispersity index of the biopolymer extracted from Haliptilon subulatum, it is similar to published values ​​for k-carrageenan (1.66) and i-carrageenan (1.63) [39] but on the other hand it is superior to that of λ-carrageenan (1.1) published by [40]. Figure 2: The separation of the different polysaccharide chains according to their size-by-size exclusion.3.6 Antioxidant activity of poly-and oligosaccharides from Haliptilon subulatum3.6.1 Scavenging activity against DPPH radicalThe 2,2-diphenyl-1-picrylhydrazyl was one of the first stable free radicals used to study the structure-antioxidant activity relationship [41]. The antioxidant power of polysaccharide and oligosaccharide from Haliptilon subulatum extract was evaluated by assaying the anti-radical DPPH activity according to the method [18]. The objective of this assay is to determine the antioxidant power of polysaccharide and oligosaccharide from Haliptilon subulatum by determining the concentration (in g / L) of the fraction responsible for 50 % inhibition of DPPH radicals in the reaction medium. In Figure 3, for each concentration tested, the polysaccharide and oligosaccharide from Haliptilon subulatum extract exhibits antioxidant activity against DPPH radicals. However, from these measurements, an IC50 was estimated of 1.7 g / L for the polysaccharide fraction and 2.5 g / L for the oligasaccharide fraction. According to this result, at 1.7 g / L of the polysaccharide fraction, 50 % of the DPPH radicals are trapped while at 2.8 g / L, the oligosaccharide fraction inhibits at 50 % of the DPPH radicals (Figure 3). By comparison, the oligosaccharides fraction exhibits less significant anti-free radical activities (Anti DPPH) than the polysaccharide fraction tested at the same concentration. Figure 3: Evolution of the anti-free radical activities (DPPH radical) of the fractions: (--): Polysaccharide obtained from Haliptilon subulatum; (--): Oligosaccharides derived from the radical degradation of polysaccharides derived from Haliptilon subulatum.3.6.2 Scavenging activity against hydroxyl radicalThe FeSO4, plays a role in the production of the metal ion. The metal ion is formed to be a substantial precursor of the radical process. In this assay, it converts H2O2 into the hydroxyl radical (OH •) which is endowed with an even more marked nuisance force [42]. Most naturally occurring antioxidants have phenolic hydroxyl groups in their structures and the antioxidant properties are attributed in part to the ability of these natural compounds to scavenge free radicals (hydroxyl OH •) since it is very reactive during this reaction. The potential of polysaccharides and oligasaccharide extracted from Haliptilon subulatum as hydroxyl radical scavenger was evaluated. As observed in Figure 4, all scavenging effects against hydroxyl radical were concentration dependent. From the results obtained, both fractions were found to exhibit anti-free radical activities. The IC50 were determined to be 0.75 g / L for the polysaccharide fraction and 0.50 g / L for the oligosaccharide fraction. For low concentrations (0.01 to 0.2 g / L), the anti-free radical effect of the two fractions (poly- and oligosaccharide) of Haliptilon subulatum increases from 10 to 20 %. For a polysaccharide concentration of 0.75 g / L, the anti-radical capacity is estimated 60 % and that the oligosaccharide fraction of concentration 0.5 g / L, the anti-free radical capacity is estimated 70 %. Therefore at 0.75 g / L of the polysaccharide fraction and at 0.50 g / L of the oligosaccharide fraction, 50 % of the hydroxyl radicals (OH •) are inhibited. By comparison, the oligosaccharide fraction exhibits greater anti-radical (anti-hydroxyl) activities than the polysaccharide fraction tested at the same concentration. The results obtained in our study remain comparable with those from the literature for other antioxidant red algae polysaccharides, possessing an anti-hydroxyl radical effect [21, 43].Figure 4: Evolution of the anti-radical activities (hydroxyl radical) of the fractions: (--): Polysaccharide obtained from Haliptilon Subulatum; (-∆-): Oligosaccharides resulting from the radical degradation of polysaccharides resulting from Haliptilon subulatum.3.6.3 Scavenging activity against superoxide anion The superoxide ion •O2– is very reactive during the reaction. Thanks to naturally occurring antioxidants having hydroxyphenolic groups in their structures, antioxidant properties are attributed in part to the ability of these compounds. A superoxide anion radical can also be produced by biological processes in vivo leading to the formation of hydrogen peroxide (H2O2) by dismutation reactions [44]. Superoxide radical species was well-known to be a precursor of harmful ROS to cellular compounds [20]. In fact, • O2– radicals were one of the precursors in the synthesis of singlet oxygen and hydroxyl radical and then could initiate the lipid peroxidation reactions [45]. In this context, the superoxide anion (•O2–) scavenging effect of the polysaccharide and oligosaccharides from the Haliptilon subulatum has been tested. The objective is to trap free radicals (superoxide anion •O2– by the polysaccharide and oligosaccharide extract) and aims to evaluate the concentration (in g / L) of the fraction responsible for 50% inhibition of radicals superoxide anion (•O2–). Figure 5 depicts the inhibitory effect of polysaccharides and oligasaccharide solutions on superoxide anion radical at all tested concentrations.It was clearly observed that this scavenging effect increased with concentration-dependent manner. The IC50, were estimated to be 7 g / L for the oligosaccharide fraction and the polysaccharide fraction not determined. Only the oligosaccharide fraction exhibits 50 % inhibition of superoxide anion radicals (Figure 5). At 7 g / L of oligosaccharide solution, the anti-free radical capacity is estimated at 50 %. Therefore, the oligosaccharide fraction exhibits greater anti-radical superoxide anion activities than the polysaccharide fraction tested at the same concentration.Figure 5: Evolution of the anti-radical activities (superoxide radical anion) of the fractions: (--): Polysaccharide obtained from Haliptilon Subulatum; (-∆-): Oligosaccharides resulting from the radical degradation of polysaccharides resulting from Haliptilon subulatum.3.6.4 Reducing powerThe vitamin C (ascorbic acid) is considered the most important water-soluble antioxidant in extracellular fluids. Thanks to the low redox potential of the ascorbate / radical ascorbyte couple, vitamin C are very effective scavengers of free radicals (•O2-, H2O2, HO•, and oxygen singlet O2) because almost all free radicals can intervene in a biological system [46, 47]. In general, the goal is to compare the reducing power between extract the polysaccharide, oligosaccharide and vitamin C using a protocol adapted from [21]. Yan et al., (2005), an antioxidant molecule allows the reduction of Fe3+ ion (from potassium ferricyanide) to the Fe2+ ion. Therefore, by adding FeCl3 in the mixture a specific, blue-colored complex was produced Yan et al., (2005) [48]. Consequently, the reducing power of natural compound can be estimated by measuring the complex formation at 700 nm. Thus, the reducing power of the natural compound can be estimated by measuring the formation of the complex at 700 nm. In this present study, we have evaluated the reducing power of the polysaccharide and oligosaccharide extract of Haliptilon subulatum. As depicted in Figure 6; the absorbance at 700 nm of the solution of polysaccharides and oligosaccharide increased by increasing the concentration. Nevertheless, as compared with ascorbic acid (used as a control), the reducing power of polysaccharides and oligosaccharides is very low. In fact, at the same high concentration (10 g / L), the absorbance of ascorbic acid 1,4 and polysaccharide, oligosaccharide was 0, 39 and 0.7, respectively.Figure 6: Estimation of the reducing power of the fractions: (--): Polysaccharide derived from Haliptilon Subulatum; (-∆-): Oligosaccharides derived from the radical degradation of polysaccharides derived from Haliptilon subulatum; (--): Vitamin C.5. CONCLUSION A fraction rich in galactose and high molecular weight sulphate with the polydispersity index of 1.67 was extracted from the red algae of Haliptilon subulatum (Rhodophyceae) collected from the coast in the North of Madagascar. Analysis by infrared spectrometry (IR) indicates the presence of sulfate groups in position 4 of certain monosaccharides and of a 3,6-anhydrogalactose bridge on the polysaccharide chains. The Haliptilon subulatum polysaccharide is of the galactan type sulphated in position 4. Like most galactans, this polysaccharide consists of a disaccharide repeating unit of galactose residues linked in β-(1,3) and α-(1, 4). The and oligosaccharides showed that these two fractions possess antioxidant activity. The high extraction yields associated with the ease of cultivation of this still little exploited species and well adapted to the climate of north Madagascar make it a good candidate to produce thickeners and compounds with antioxidant activity. In addition, all the results open up valuations.Acknowledgment The authors would like to thank Pr Phillippe MICHAUD, Guillaume PIERRE and Cédric DELATTRE for their support and to analyze of the sample of polysaccharide and oligosaccharide extract in the laboratory CNRS, UMR 6602, IP, F-63178 Aubière, France of the Pascal institute of l 'Blaise Pascal University.6. REFERENCES Berne F., Cordonnier J. Industrial water treatment. Edition Technip Paris. 1995; pp:253.Kloareg B., & Quatrano R.S. 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