Jeanny S. Maciel

Structural characterization of polysaccharide obtained from red seaweed Gracilaria caudata (J Agardh).

Seaweeds are considered an important source of bioactive molecules. In this work the marine red alga Gracilaria caudata was submitted to aqueous extraction of their polysaccharides for 2 h at 100 °C. The polysaccharide fraction (PGC) presented a recovery of 32.8%. The sulfate content of PGC, calculated by S%, is 1 ± 0.2% and the degree of sulfation accounts for 0.13 ± 0.2. High-Performance Size-Exclusion Chromatography demonstrated that PGC consists of a high molecular weight polysaccharide (2.5 × 10(5)gmol(-1)). Chemical analysis of PGC was performed by microanalysis, infrared (FT-IR) and nuclear magnetic resonance (NMR, 1 and 2D) spectroscopy. The structure of PGC is mainly constituted by the alternating residues 3-linked-β-D-galactopyranose and 4-linked-3,6-α-L-anhydrogalactose; however some hydroxyl groups were substituted by methyl groups and pyruvic acid acetal. The biological precursor of 3,6-α-L-anhydrogalactose (6-sulfate-α-l-galactose) was also detected.

Oxidation of cashew tree gum exudate polysaccharide with TEMPO reagent

Cashew gum (CG), an exudate polysaccharide from Anacardium ocidentale trees, was oxidized with TEMPO reagent and the 7product (CGOX) characterized by spectroscopic techniques (FT-IR and NMR), chromatographic analyses (HPLC and GPC), viscosity measurements and thermal analysis (TGA). The yield of the reaction product was 96%. The uronic acid content in starting gum (7.2 m%) was increased to 36 m%. The degree of oxidation based on free galactose and glucose units was 68%. NMR data show that oxidation occurred preferentially at primary carbons of galactose units. High degradation degree after oxidation was estimated by the difference on the expected and observed hCGOX/hCG ratio. The presence of organic and inorganic impurities in the new polyelectrolyte was detected by TGA. A less thermally stable cashew gum is formed after the oxidation with TEMPO based on initial decomposition temperature and IPDT.

Sulfated chitosan as tear substitute with no antimicrobial activity.

Chitosan of high molar mass and with 82% deacetylation was sulfated using two procedures and characterized. In the first method sample chitosan-S1 was produced using chlorosulfonic acid as the sulfating agent and N,N-dimethylformamide as the medium, and in the second method (chitosan-S2) formic acid was also used. The degrees of sulfation were 0.87 (chitosan-S1) and 0.67 (chitosan-S2). FTIR spectra showed bands at 1230, 800 and 580 cm(-1), attributed to sulfation. Moisture content followed the order: chitosan-S-0.87>chitosan-S-0.67>chitosan. Chain depolymerization was verified by GPC. Aqueous solutions showed pseudoplastic behavior and the viscosity at a concentration of 0.3% (w/v) was higher than that of healthy human tears (close to 3 mPas at shear rate 130 s(-1)). Substitutions in the C2NH and in C6OH groups were verified by NMR. Antimicrobial activity against Staphylococcus aureus and Pseudomonas aeruginosa was not observed. Considering that chitosan-S-0.67 had a higher solubility, less chain depolymerization, higher yield and better thermal stability in comparison with chitosan-S-0.87, the derivative with DS 0.67 offered the greatest potential for use in formulations of tear substitutes.

Polysaccharide fraction isolated from Passiflora edulis inhibits the inflammatory response and the oxidative stress in mice

The aim of the study was to investigate the anti‐inflammatory, antioxidant and antinociceptive actions of PFPe, a polysaccharide fraction isolated from the dried fruit of the Passiflora edulis.

Quaternized cashew gum: An anti-staphylococcal and biocompatible cationic polymer for biotechnological applications

Chemical modifications to cashew gum (CG) structure have been previously reported to obtain new physicochemical characteristics, however until now there were no reports of modifications by introduction of new functional groups to add cationic character. This study presents a quaternization route for CG using a quaternary ammonium reagent. The chemical features of the quaternized cashew gum derivatives (QCG) were analyzed by: FTIR, elemental analysis, degree of substitution, Zeta potential, 1H NMR and 1H-13C correlation (HSQC). QCG were evaluated for their anti-staphylococcal activity by determining minimum inhibitory and bactericidal concentrations against pathogenic Staphylococcus spp. and by imaging using atomic force microscopy. Moreover, the mammalian cell biocompatibility were also assessed through hemolytic and cell toxicity assays. QCG presented promising antimicrobial activity against methicillin-resistant S. aureus and biocompatibility on tested cells. These results show that QCG could be a promising tool in the development of biomaterials with an anti-septic action.

The potential of cashew gum functionalization as building blocks for layer-by-layer films

Cashew gum (CG), an exudate polysaccharide from Anacardium occidentale trees, was carboxymethylated (CGCm) and oxidized (CGO). These derivatives were characterized by FTIR and zeta potential measurements confirming the success of carboxymethylation and oxidation reactions. Nanostructured multilayered films were then produced through layer-by-layer (LbL) assembly in conjugation with chitosan via electrostatic interactions or Schiff bases covalent bonds. The films were analyzed by QCM-D and AFM. CG functionalization increased the film thickness, with the highest thickness being achieved for the lowest oxidation degree. The roughest surface was obtained for the CGO with the highest oxidation degree due to the predominance of covalent Schiff bases. This work shows that nanostructured films can be assembled and stabilized by covalent bonds in alternative to the conventional electrostatic ones. Moreover, the functionalization of CG can increase its feasibility in multilayers films, widening its potential in biomedical, food industry, or environmental applications.

Efeito da modificação química na solubilidade e intumescimento de microesferas à base de goma do cajueiro carboximetilada e quitosana

Esferas de goma do cajueiro carboximetilada e quitosana foram produzidas via complexacao polieletrolitica. As esferas foram modificadas quimicamente de modo a obter-se sistemas estaveis em meio acido e que apresentassem uma resposta de intumescimento diferenciado frente a variacao de pH. As esferas foram modificadas por reacetilacao da quitosana e por reticulacao com epicloridrina, glutaraldeido e genipina. As esferas reticuladas foram caracterizadas por meio de tecnicas como: espectroscopia de absorcao no infravermelho, analise termogravimetrica, microscopia eletronica de varredura e quanto a solubilidade em pH 1,2 e ao intumescimento. As esferas de goma do cajueiro carboximetilada e quitosana reacetilada, e as esferas reticuladas com epicloridrina apresentaram baixa resistencia a dissolucao em pH 1,2. Entretanto, as esferas reticuladas com glutaraldeido e genipina apresentaram resistencia a dissolucao e baixo coeficiente de difusao. As esferas reticuladas com genipina apresentaram um grau de intumescimento maior do que as esferas reticuladas com glutaraldeido nas concentracoes de 3% e 5% (massa/volume). As esferas reticuladas com genipina apresentaram intumescimento responsivo a variacao de pH e estabilidade em pH 1,2, indicando que esses sistemas possuem potencial para uso em sistemas de liberacao controlada de farmacos por via oral.