Microalgae: A Promising Source of Bioactive Phycobiliproteins.

Phycobiliproteins are photosynthetic light-harvesting pigments isolated from microalgae with fluorescent, colorimetric and biological properties, making them a potential commodity in the pharmaceutical, cosmetic and food industries. Hence, improving their metabolic yield is of great interest. In this regard, the present review aimed, first, to provide a detailed and thorough overview of the optimization of culture media elements, as well as various physical parameters, to improve the large-scale manufacturing of such bioactive molecules. The second section of the review offers systematic, deep and detailed data about the current main features of phycobiliproteins. In the ultimate section, the health and nutritional claims related to these bioactive pigments, explaining their noticeable potential for biotechnological uses in various fields, are examined.

Structural Characterization and Rheological and Antioxidant Properties of Novel Polysaccharide from Calcareous Red Seaweed.

A novel sulfated xylogalactan (JASX) was extracted and purified from the rhodophyceae Jania adhaerens. JASX was characterized by chromatography (GC/MS-EI and SEC/MALLS) and spectroscopy (ATR-FTIR and 1H/13C NMR) techniques. Results showed that JASX was constituted by repeating units of (→3)-ß-d-Galp-(1,4)-3,6-α-l-AnGalp-(1→)n and (→3)-ß-d-Galp-(1,4)-α-l-Galp-(1→)n substituted on O-2 and O-3 of the α-(1,4)-l-Galp units by methoxy and/or sulfate groups but also on O-6 of the ß-(1,3)-d-Galp mainly by ß-xylosyl side chains and less by methoxy and/or sulfate groups. The Mw, Mn, D, [η] and C* of JASX were respectively 600 and 160 kDa, 3.7, 102 mL.g-1 and 7.0 g.L-1. JASX exhibited pseudoplastic behavior influenced by temperature and monovalent salts and highly correlated to the power-law model and the Arrhenius relationship. JASX presented thixotropic characteristics, a gel-like viscoelastic behavior and a great viscoelasticity character. JASX showed important antioxidant activities, outlining its potential as a natural additive to produce functional foods.

Bioactive Carbohydrate Polymers-Between Myth and Reality.

Polysaccharides are complex macromolecules long regarded as energetic storage resources or as components of plant and fungal cell walls. They have also been described as plant mucilages or microbial exopolysaccharides. The development of glycosciences has led to a partial and difficult deciphering of their other biological functions in living organisms. The objectives of glycobiochemistry and glycobiology are currently to correlate some structural features of polysaccharides with some biological responses in the producing organisms or in another one. In this context, the literature focusing on bioactive polysaccharides has increased exponentially during the last two decades, being sometimes very optimistic for some new applications of bioactive polysaccharides, notably in the medical field. Therefore, this review aims to examine bioactive polysaccharide, taking a critical look of the different biological activities reported by authors and the reality of the market. It focuses also on the chemical, biochemical, enzymatic, and physical modifications of these biopolymers to optimize their potential as bioactive agents.

Bioactive Polysaccharides from Seaweeds.

Bioactive compounds with diverse chemical structures play a significant role in disease prevention and maintenance of physiological functions. Due to the increase in industrial demand for new biosourced molecules, several types of biomasses are being exploited for the identification of bioactive metabolites and techno-functional biomolecules that are suitable for the subsequent uses in cosmetic, food and pharmaceutical fields. Among the various biomasses available, macroalgae are gaining popularity because of their potential nutraceutical and health benefits. Such health effects are delivered by specific diterpenes, pigments (fucoxanthin, phycocyanin, and carotenoids), bioactive peptides and polysaccharides. Abundant and recent studies have identified valuable biological activities of native algae polysaccharides, but also of their derivatives, including oligosaccharides and (bio)chemically modified polysaccharides. However, only a few of them can be industrially developed and open up new markets of active molecules, extracts or ingredients. In this respect, the health and nutraceutical claims associated with marine algal bioactive polysaccharides are summarized and comprehensively discussed in this review.

Effects of nutritional conditions on growth and biochemical composition of Tetraselmis sp.

BACKGROUND: This study aimed to maximize biomass concentration, biomass productivity and biochemical composition of the marine microalga Tetraselmis sp. METHODS: In the current study, Box-Behnken Design was used to model the effect of NaNO3, NaH2PO4, metals and vitamins in the F/2 medium on the growth, total chlorophylls, carotenoids and starch contents. The total chlorophylls content was quantified by spectrophotometry. The FT-IR spectroscopy was used to estimate the biochemical compositions of Tetraselmis sp. grown under both optimized medium culture for starch production and standard culture medium. RESULTS: Finalized NaNO3 (1.76 mM), NaH2PO4 (0.018 mM), metals (1500 µL.L-1) and vitamins (312.5 µL.L-1) concentrations, generated an increase in biomass concentration up to 5.72 g.L-1 which contributed to an increase about 2.4-fold than that of the standard conditions of biomass productivity (408.57 mg.L-1.day-1). The maximum value of carotenoids content (0.3 mg.g DW-1) was achieved at the highest level of all factors. The total chlorophylls content reached also its maximum (5.18 mg.g DW-1) at high nitrate (1.76 mM), phosphate (0.054 mM), metals and vitamins concentrations, while the maximum starch content (42% DW) was achieved with low nitrate and phosphate concentrations (0.58 mM and 0.027 mM) and with metals and vitamins limitations. Thus, the nitrogen, phosphorus, metals and vitamins limitations led to divert the metabolism for the starch biosynthesis. CONCLUSIONS: The high biomass concentration productivity and starch production make Tetraselmis sp. strain a good candidate for biotechnological applications.

Improving the shelf life of minced beef by Cystoseira compressa polysaccharide during storage.

A polysaccharide extracted from the brown alga Cystoseira compressa (CCPS) was evaluated as a food additive to extend the shelf-life of raw beef meat. The antioxidant potential of CCPS was demonstrated by its inhibition of ß-carotene bleaching (64.28 %), superoxide radicals (70.12 %), and hydroxyl radicals (93 %) at a concentration of 10 mg/ml. The polysaccharide also showed antibacterial activity with MIC values between 6.25 mg/ml and 50 mg/ml against five foodborne pathogenic bacteria. Furthermore, CCPS exhibited excellent functional, foaming, and emulsifying properties. Furthermore, microbiological and chemical effects of CCPS at concentrations equivalent to 1 MIC (CCPS-1), 2 MIC (CCPS-2), and 4 MIC (CCPS-3) were conducted. Chemical analyses showed that treated beef had significantly reduced TBARS levels below 2 mg MDA/kg at day 14. The treatment also decreased carbonyl groups, improved heme iron transformation, inhibited microbial growth (p < 0.05), and kept MetMb levels below 40 % by day 14. Moreover, two multivariate approaches, principal component analysis (PCA) and hierarchical cluster analysis (HCA), were effectively used to analyze the results characterizing the main attributes of the stored meat samples. In conclusion, these findings demonstrated that CCPS could be employed as a functional and bioactive component in the meat industry.

Microalgae as feedstock for bioactive polysaccharides.

Due to the increase in industrial demand for new biosourced molecules (notably bioactive exopolysaccharides (EPS)), microalgae are gaining popularity because of their nutraceutical potential and benefits health. Such health effects are delivered by specific secondary metabolites, e.g., pigments, exopolysaccharides, polyunsaturated fatty acids, proteins, and glycolipids. These are suitable for the subsequent uses in cosmetic, nutraceutical, pharmaceutical, biofuels, biological waste treatment, animal feed and food fields. In this regard, a special focus has been given in this review to describe the various methods used for extraction and purification of polysaccharides. The second part of the review provides an up-to-date and comprehensive summary of parameters affecting the microalgae growth and insights to maximize the metabolic output by understanding the intricacies of algal development and polysaccharides production. In the ultimate part, the health and nutraceutical claims associated with marine algal bioactive polysaccharides, explaining their noticeable potential for biotechnological applications, are summarized and comprehensively discussed.

Influence of the sulfate content of the exopolysaccharides from Porphyridium sordidum on their elicitor activities on date palm vitroplants.

Given the increasing interest that is being paid to polysaccharides derived from algae as plant natural defense stimulators, the degree of sulfation of exopolysaccharides produced by P. sordidum for inducing defense responses in date palm vitroplants was investigated. Firstly, the culture parameters of P. sordidum were optimized to maximize the amount of sulfate in EPS using a Box-Behnken experimental design and the elicitor effects of two EPS which differ in the sulfation degrees were compared. Results demonstrated that the concentrations of NaCl, NaNO3 and MgSO4 set at 28, 0.54 and 16.31 g/L, respectively yielded the best sulfate contents. To elucidate defense-inducing activities in date palm vitroplants, EPS with the highest sulfate content (EPS1) were prepared for comparison with those obtained under standard conditions (EPS0). A fucoidan extracted from Cystoseira compressa was used as positive control and MgSO4 as negative control. Both EPS and the fucoidan displayed H2O2 accumulation and expression of PR1, SOD, PAL and WRKY genes. Interestingly, EPS1 was significantly more bioactive than EPS0 and the fucoidan suggesting that the elicitor activity is positively correlated with the sulfate groups content of this polysaccharide.

Optimization of Exopolysaccharides Production by Porphyridium sordidum and Their Potential to Induce Defense Responses in Arabidopsis thaliana against Fusarium oxysporum.

Polysaccharides from marine algae are one novel source of plant defense elicitors for alternative and eco-friendly plant protection against phytopathogens. The effect of exopolysaccharides (EPS) produced by Porphyridium sordidum on elicitation of Arabidopsis thaliana defense responses against Fusarium oxysporum was evaluated. Firstly, in order to enhance EPS production, a Box-Behnken experimental design was carried out to optimize NaCl, NaNO3 and MgSO4 concentrations in the culture medium of microalgae. A maximum EPS production (2.45 g/L) higher than that of the control (0.7 g/L) was observed for 41.62 g/L NaCl, 0.63 g/L NaNO3 and 7.2 g/L MgSO4 concentrations. Structurally, the EPS contained mainly galactose, xylose and glucose. Secondly, the elicitor effect of EPS was evaluated by investigating the plant defense-related signaling pathways that include activation of Salicylic or Jasmonic Acid-dependent pathway genes. A solution of 2 mg/mL of EPS has led to the control of fungal growth by the plant. Results showed that EPS foliar application induced phenylalaline ammonia lyase and H2O2 accumulation. Expression profile analysis of the defense-related genes using qRT-PCR revealed the up-regulation of Superoxide dismutases (SOD), Peroxidase (POD), Pathogenesis-related protein 1 (PR-1) and Cytochrome P450 monooxyge-nase (CYP), while Catalase (CAT) and Plant defensin 1.2 (PDF1.2) were not induced. Results suggest that EPS may induce the elicitation of A. thaliana's defense response against F. oxysporum, activating the Salicylic Acid pathway.

Structural features and rheological behavior of a water-soluble polysaccharide extracted from the seeds of Plantago ciliata Desf.

A water-soluble polysaccharide (PSPC) was extracted from the seeds of Plantago ciliata Desf., a spontaneous Algerian Saharan plant by a hot aqueous extraction then purified by successive ethanolic precipitations. The final extraction yield for PSPC was close to 18.6% (w/v). PSPC was then investigated regarding its global composition, structural features and rheological properties. PSPC is a neutral arabinoxylan, composed of a ß-(1,3)/ß-(1,4)-d-xylan backbone with side chains of Xylp, and Araf residues attached in O-2 and O-3 positions. The macromolecular characteristics of PSPC in water was determined by SEC/MALLS, with a high molecular weight (Mw) of 700 kDa, a low polydispersity index (PDI) of 1.47 and an intrinsic viscosity [η] close to 157 mL/g. PSPC showed a pseudoplastic behavior in semi-dilute media and the critical overlay concentration (C*) was estimated around 0.32-0.37% (w/v). This current research has supplied original structural information on a new arabinoxylan which could be particularly useful as a novel source of soluble fiber belonging to psyllium.

Novel Antioxidant, Anti-α-Amylase, Anti-Inflammatory and Antinociceptive Water-Soluble Polysaccharides from the Aerial Part of Nitraria retusa.

In this paper, water-soluble polysaccharides (named as NRLP) were extracted from Nitraria retusa leaves. The main structural features of NRLP were determined by High-pressure size exclusion chromatography, Fourier transform infrared and Gas Chromatography/Mass Spectrometry-Electronic Impact analysis. The in vitro and in vivo biological potential of NRLP were evaluated by measuring its antioxidant (•OH and DPPH• scavenging, total antioxidant capacity), anti-α-amylase as well as anti-inflammatory and antinociceptive activities in a mice model. NRLP was composed of Rha (33.7%), Gal (18.1%), GalA (15.0%), Glc (13.3%), Ara (13.3%), Xyl (3.8%), and GlcA (2.8%) and showed a Molecular Weight (Mw) of 23.0 kDa and a polydispersity index (PDI) of 1.66. The investigations highlighted a significant antioxidant activity (IC50 = 2.4-2.6 mg/mL) and an inhibition activity against α-amylase (IC50 = 4.55 mg/mL) in a dose-dependent manner. Further, NRLP revealed interesting anti-edematous effects and antinociceptive activities (both > 70%). These results open up new pharmacological prospects for the water-soluble polysaccharides extracted from Nitraria retusa leaves.

Structural characterization of water-soluble polysaccharides from Nitraria retusa fruits and their antioxidant and hypolipidemic activities.

The structure, antioxidant and anti-hyperlipidemic activities of polysaccharides from Nitraria retusa fruits (named as NRFP) were investigated. The NRFP fraction, with a molecular weight of 66.5 kDa, was composed of a ß-(1 → 3)-glucan, containing neutral sugars (69.1%) but also uronic acids up to 23.1% due to pectin structure. The monosaccharide composition highlighted a polymer composed of glucose (41.4%), galacturonic acid (30.5%), galactose (12.6%), arabinose (11.8%) and rhamnose (3.70%). In the antioxidant assays, NRFP exhibited effective total antioxidant capacity (IC50 = 7.82 mg/ml), scavenging activities on DPPH radical (IC50 = 0.87 mg/ml) and hydrogen peroxide (IC50 = 2.03 mg/ml). In addition, NRFP proved protective effects on H2O2 induced hemolysis (IC50 = 66.2 µg/ml). In vivo NRFP reduced the hyperlipidemia, hepatotoxicity, cardiovascular and coronary diseases induced by Triton X-100.

Optimal cultivation towards enhanced biomass and floridean starch production by Porphyridium marinum.

Optimal conditions for maximal biomass and starch production by the marine red microalgae Porphyridium marinum were investigated. Box-Behnken Design was used to model the effect of light intensity, NaNO3 concentration and salinity on the growth of microalgae but also on their starch and protein contents. These three factors increased biomass production by 13.6% in optimized conditions. A maximum starch production (140.21 µg·mL-1), 30.6% higher than that of the control, was attained at a light intensity of 100 µmol photons·m-2·s-1, a NaNO3 concentration of 1 g·L-1 and a NaCl concentration of 20 g·L-1. FT-IR spectroscopy was used to estimate the biochemical composition (carbohydrate accumulation) of P. marinum and revealed significant changes (P < 0.05) depending on culture conditions. FT-IR analysis highlighted also that the culture conditions leading to highest starch production by P. marinum corresponded to lowest sulfated polysaccharide and protein contents.

Quality Characteristics and Functional and Antioxidant Capacities of Algae-Fortified Fish Burgers Prepared from Common Barbel (Barbus barbus).

INTRODUCTION: Algae have been used as natural ingredients to produce new canned fish burgers prepared from minced flesh of common barbel. In this research, the impact of the addition of Cystoseira compressa and Jania adhaerens at concentrations of 0.5, 1, and 1.5% w/v on the texture and sensory characteristics of fish burgers were investigated. RESULTS: Compared to controls, fish burgers containing 1% algae had better texture and sensory properties (P < 0.05). Also, these burger formulations had higher water and oil holding capacities as well as swelling ability, due to the important polysaccharides and dietary fibers contents of algae. In addition, algae-supplemented burgers were characterized as having low L⁎, a⁎, and b⁎ values, which made the color appear to be paler. Thanks to their high richness in pigments (chlorophylls and carotenoids) and polysaccharides, algae considerably enhance the antioxidant activities of the new ready-to-eat fish burgers. So, Cystoseira compressa and Jania adhaerens could be used as nutritious additives to produce new fish-based products.

Structural characterization and antioxidant activity of water-soluble polysaccharides from the Tunisian brown seaweed Cystoseira compressa.

A fucoidan (CCF) and a sodium alginate (CCSA) were extracted and purified from the Tunisian brown seaweed Cystoseira compressa. CCF was a highly sulfated heterogalactofucan composed of α-(1→3), α-(1→4)-linked l-Fucp as main backbone which could be highly branched (31.84%) at O-3 and O-4 positions of α-(1→4)-l-Fucp and α-(1→3)-l-Fucp by terminal monosaccharides and side chains such as terminal α-l-Fucp, terminal ß-d-Galp, ß-d-Galp-(1→3)-α-l-Fucp and ß-d-Galp-(1→4)-α-l-Fucp. The ratio of α-(1→3)/α-(1→4) linkages was estimated at 3.86:1. CCSA was characterized by HPAEC-PAD, GC/MS-EI, ATR-FTIR, and 1H-NMR. The M/G ratio was M/G = 0.77, indicating that CCSA respectively contained 44% and 56% of mannuronic and guluronic acids. The values of FGG, FMM, FGM (or FMG) blocks as well as the parameter η were estimated. The two polysaccharides exhibited effective antioxidant activities by ferrous ion chelation, ferric ion reduction and DPPH radical-scavenging, outlining their potentials as natural additives.

Modelling Tetraselmis sp. growth-kinetics and optimizing bioactive-compound production through environmental conditions.

The aim of this study is to predict Tetraselmis cells growth-kinetic and to induce the synthesis of bioactive compounds (chlorophylls, carotenoids and starch) with high potential for biotechnological applications. Using the statistical criteria, the Baranyi-Roberts model has been selected to estimate the microalgae growth-kinetic values. The simultaneous effects of salinity, light intensity and pH of culture medium were investigated to maximize the production of total chlorophylls, carotenoids and starch. The optimal culture conditions for the production of these compounds were found using Box-Behnken Design. Results have shown that total chlorophyll and carotenoids were attained 21.6mg·g-1DW and 0.042mg·g-1DW, respectively. In addition, the highest starch content of 0.624g·g-1DW has been obtained at neutral pH with high irradiance (182µmolphotonsm-2 s-1) and low salinity (20). A highly correlation (R2 = 0.884) has been found between the gravimetric and flow cytometric measurements of chlorophyll content.