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.

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.

Structural characterization and rheological behavior of a heteroxylan extracted from Plantago notata Lagasca (Plantaginaceae) seeds.

Plantago notata (Plantaginaceae) is a spontaneous plant from Septentrional Algerian Sahara currently used by traditional healers to treat stomach disorders, inflammations or wound healing. A water-soluble polysaccharide, called PSPN (PolySaccharide fraction from Plantago Notata), was extracted and purified from the seeds of this semi-arid plant. The structural features of this mucilage were evaluated by colorimetric assays, Fourier transformed infrared spectroscopy (FT-IR), gas chromatography coupled to mass spectrometry (GC/MS) and 1H/13C Nuclear Magnetic Resonance (NMR) spectroscopy. PSPN is a heteroxylan with a backbone composed of ß-(1,3)-d-Xylp and ß-(1,4)-d-Xylp highly branched, through (O)-2 and (O)-3 positions of ß-(1,4)-d-Xylp by various side chains and terminal monosaccharides such as α-l-Araf-(1,3)-ß-d-Xylp, ß-d-Xylp-(1,2)-ß-d-Xylp, terminal Xylp or terminal Araf. The physico-chemical and rheological analysis of this polysaccharide in dilute and semi diluted regimes showed that PSPN exhibites a molecular weight of 2.3×106g/mol and a pseudoplastic behavior.