Monique Gabriela das Chagas Faustino Alves

A sulfated polysaccharide, fucans, isolated from brown algae Sargassum vulgare with anticoagulant, antithrombotic, antioxidant and anti-inflammatory effects.

Fucan (SV1) sulfated polysaccharides from the brown algae Sargassum vulgare were extracted, fractionated in acetone and examined with respect to chemical composition, anticoagulant, anti-inflammatory, antithrombotic effects and cellular proliferation. These polysaccharides contain low levels of protein, high level of carbohydrate and sulfate. Monosaccharides analysis revealed that SV1 was composed of fucose, galactose, xylose, glucuronic acid and mannose. SV1 polysaccharide prolonged activated partial thromboplastin time (aPTT) and exhibited high antithrombotic action in vivo, with a concentration ten times higher than heparin activity. PSV1, a purified form in gel filtration showed very low biological activities. SV1 stimulated the enzymatic activity of FXa. Its action on DPPH radical scavenging activity was 22%. This polymer has no cytotoxic action (hemolytic) on ABO and Rh blood types in different erythrocyte groups. It displays strong anti-inflammatory action at all concentrations tested in the carrageenan-induced paw edema model, demonstrated by reduced edema and cellular infiltration.

Antiangiogenic activity and direct antitumor effect from a sulfated polysaccharide isolated from seaweed

Angiogenesis is a dynamic proliferation and differentiation process. It requires endothelial proliferation, migration and tube formation. In this context, endothelial cells are a preferred target for several studies and therapies. Anionic polysaccharides (SV1 and PSV1) from brown seaweed Sargassum vulgare were fractionated (SV1), purified (PSV1) and displayed with high total sugars, sulfate content and very low level of protein. The antiangiogenic efficacy of polysaccharides was examined in vivo in the chick chorioallantoic membrane (CAM) model by using fertilized eggs. Decreases in the density of the capillaries were assessed and scored. The results showed that SV1 and PSV1 have an inhibitory effect on angiogenesis. These results were also confirmed by the inhibition of tubulogenesis in rabbit aorta endothelial cell (RAEC) in matrigel. These compounds were assessed in an apoptosis assay (Annexin V-FITC/PI) and cell viability by MTT assay of RAEC. These polysaccharides did not affect the viability and did not have apoptotic or necrotic action. RAEC cell when incubated with SV1and PSV1 showed inhibition of VEGF secretion, observed when compounds were incubated at 25, 50 and 100 μg/μL. The VEGF secretion with the RAEC cell line for 24 h was more effective for PSV1 at 50 μg/μL (71.4%) than for SV1 at 100 μg/μL (75.9%). SV1 and PSV1 had an antiproliferative action (47%) against tumor cell line HeLa. Our results indicate that these sulfated polysaccharides have antiangiogenic and antitumor actions.

Antioxidant and Anti-Inflammatory Properties of an Extract Rich in Polysaccharides of the Mushroom Polyporus dermoporus.

Polyporus dermoporus mushroom, native to Brazil, is produced under natural conditions in the unexplored reserve of Mata da Estrela-Rio Grande do Norte-RN. These mushrooms were delipidated with chloroform:methanol (2:1 v/v), extracted with water at 100 °C, and fractionated with ethanol (one and three volumes) and then centrifuged. The ethanol precipitation showed a high total sugar level of 64.8% and 1% of protein. This precipitate contained a high glucan level, characterized by chemical methods and by NMR of 13C and 1H and spectroscopy. The 13C NMR spectrum of these mushroom extracts showed the presence of β-glucose by a signal at 103.25 ppm. Studies with these glucans were made to elucidate antioxidant and anti-inflammatory activities. This extract of glucans inhibited the lipid peroxidation (42.9%) and superoxide radicals (83.3%) at 67 μg/mL. However, the inhibition of hydroxyl radical by the extract of this mushroom was 96% at 267 μg/mL. The action of this extract on induced pleurisy showed a 92.5% and 68.7% reduction in polymorphonuclears cells and nitric oxide, respectively, at 30 mg/kg. The glucans reduced the croton oil-induced ear edema by 65.6% at 30 mg/kg.

Extraction process optimization of sulfated galactan-rich fractions from Hypnea musciformis in order to obtain antioxidant, anticoagulant, or immunomodulatory polysaccharides

The seaweed Hypnea musciformis synthesizes sulfated galactans and these galactans have been reported to have antioxidant, anticoagulant, and immunostimulatory properties. However, efficient extraction of these polysaccharides depends on the particular extraction method used, some of these polysaccharides are not extracted. Previously, we obtained galactans with different properties by using a simple extraction method. Here, we performed slight modifications to the extraction method, which led to variation in the type of polysaccharides obtained and their biological activity. We obtained four sulfated galactan-rich fractions named as FT4v, FT6v, FT8v, and FT10v. The chemical composition data showed that the fractions had high sugar and sulfate contents. Fraction FT4v exhibited the highest sulfate/sugar ratio (0.47), while FT6v (0.37), FT8v (0.39), and FT10v (0.39) presented lower sulfate/sugar ratios. Fractions FT4v and FT6v showed the highest antioxidant activity. Fraction FT4v also exhibited the greatest anticoagulant potential; however, other fractions presented marked immunomodulatory action. FT10v stimulated the highest levels of NO production whereas FT6v stimulated the highest expression of interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α) in RAW cells. Fraction FT10v exhibited the greatest cytotoxic action of the obtained fractions against HeLa and 786 cell lines. In vitro tests showed that the sulfated galactan-rich fractions isolated from H. musciformis with low sulfate/sugar ratios, i.e., the fractions containing fewer sulfated polysaccharides (FT6v, FT8v, and FT10v), showed marked immunostimulatory action while the fraction with the high sulfate/sugar ratio (FT4v) exhibited improved anticoagulant activity. Therefore, our results suggest that different extraction conditions promote the acquisition of sulfated galactan-rich fractions from H. musciformis with different biological activities.

Antibacterial, Antiproliferative, and Immunomodulatory Activity of Silver Nanoparticles Synthesized with Fucans from the Alga Dictyota mertensii

In this study, we aimed to synthesize silver nanoparticles containing fucans from Dictyota mertensii (Martius) Kützing using an environmentally friendly method and to characterize their structure as well as antiproliferative, immunomodulatory, and antibacterial effects. Fucan-coated silver nanoparticles (FN) were characterized by Fourier-transform infrared analysis, dynamic light scattering, zeta potential, atomic force microscopy, energy dispersive X-ray spectroscopy, and inductively coupled plasma emission spectrometry. They were evaluated for their effect on cell viability, minimum inhibitory bactericidal concentration, and release of nitric oxide and cytokines. The FN were successfully synthesized using an environmentally friendly method. They were size-stable for 16 months, of a spherical shape, negative charge (−19.1 mV), and an average size of 103.3 ± 43 nm. They were able to inhibit the proliferation of the melanoma tumor cell line B16F10 (60%). In addition, they had immunomodulatory properties: they caused an up to 7000-fold increase in the release of nitric oxide and cytokines (IL-10; IL-6 and TNF-α) up to 7000 times. In addition, the FN showed inhibitory effect on Gram-positive and -negative bacteria, with MIC values of 50 µg/mL. Overall, the data showed that FN are nanoparticles with the potential to be used as antitumor, immunomodulatory, and antibacterial agents.

Dextran: Influence of Molecular Weight in Antioxidant Properties and Immunomodulatory Potential.

Dextrans (α-d-glucans) extracted from Leuconostoc mesenteroides, with molecular weights (MW) of 10 (D10), 40 (D40) and 147 (D147) kDa, were evaluated as antioxidant, anticoagulant and immunomodulatory drugs for the first time. None presented anticoagulant activity. As for the antioxidant and immunomodulatory tests, a specific test showed an increase in the dextran activity that was proportional to the increase in molecular weight. In a different assay, however, activity decreased or showed no correlation to the MW. As an example, the reducing power assay showed that D147 was twice as potent as other dextrans. On the other hand, all three samples showed similar activity (50%) when it came to scavenging the OH radical, whereas only the D10 sample showed sharp activity (50%) when it came to scavenging the superoxide ion. D40 was the single dextran that presented with immunomodulatory features since it stimulated the proliferation (~50%) of murine macrophages (RAW 264.7) and decreased the release of nitric oxide (~40%) by the cells, both in the absence and presence of lipopolysaccharides (LPS). In addition, D40 showed a greater scavenging activity (50%) for the hydrogen peroxide, which caused it to also be the more potent dextran when it came to inhibiting lipid peroxidation (70%). These points toward dextrans with a 40 kDa weight as being ideal for antioxidant and immunomodulatory use. However, future studies with the D40 and other similarly 40 kDa dextrans are underway to confirm this hypothesis.