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.

In vitro antioxidant, anticoagulant and antimicrobial activity and in inhibition of cancer cell proliferation by xylan extracted from corn cobs.

Xylan is one of most abundant polymer after cellulose. However, its potential has yet to be completely recognized. Corn cobs contain a considerable reservoir of xylan. The aim of this work was to study some of the biological activities of xylan obtained from corn cobs after alkaline extraction enhanced by ultrasonication. Physical chemistry and infrared analyses showed 130 kDa heteroxylan containing mainly xylose:arabinose: galactose:glucose (5.0:1.5:2.0:1.2). Xylan obtained exhibited total antioxidant activity corresponding to 48.5 mg of ascorbic acid equivalent/g of xylan. Furthermore, xylan displayed high ferric chelating activity (70%) at 2 mg/mL. Xylan also showed anticoagulant activity in aPTT test. In antimicrobial assay, the polysaccharide significantly inhibited bacterial growth of Klebsiella pneumoniae. In a test with normal and tumor human cells, after 72 h, only HeLa tumor cell proliferation was inhibited (p < 0.05) in a dose-dependent manner by xylan, reaching saturation at around 2 mg/mL, whereas 3T3 normal cell proliferation was not affected. The results suggest that it has potential clinical applications as antioxidant, anticoagulant, antimicrobial and antiproliferative compounds.

Evaluating the possible genotoxic, mutagenic and tumor cell proliferation-inhibition effects of a non-anticoagulant, but antithrombotic algal heterofucan.

Fucan is a term used to denominate a family of sulfated polysaccharides rich in L-fucose. They are extracted mainly from brown seaweeds and echinoderms. The brown seaweed Spatoglossum schröederi (Dictyotaceae) synthesizes three heterofucans named A, B and C. Our research group purified a non-anticoagulant heterofucan (fucan A) which displays antithrombotic activity in vivo. However, its in vitro toxicity has yet to be determined. This work presents the evaluation of the potential cytotoxicity, mutagenicity and genotoxicity of this fucan. After 48 h incubation fucan A cytotoxicity was determinate using MTT assay. Tumor-cell (HeLa, PC3, PANC, HL60) proliferation was inhibited 2.0-43.7%; at 0.05-1 mg ml⁻¹ of the heterofucan, the 3T3 non-tumor cell line proliferation was also inhibited (3.3-22.0%). On the other hand, the CHO tumorigenic and RAW non-tumor cell lines proliferation were not affected by this molecule (0.05-1 mg ml⁻¹). We observed no mutagenic activity in Salmonella reversion assay when bacterial strains TA97a, TA98, TA100 and TA102 (with and without S9) were used.Comet assay showed that fucan A had no genotoxic effect (from 20 to 1000 mg ml⁻¹) on CHO cells. In conclusion, this study indicates that the S. schröederi fucan A was not found to be genotoxic or mutagenic compound; thus it could be used in new antithrombotic drug development.

Assessment of zymosan-induced leukocyte influx in a rat model using sulfated polysaccharides.

Fucoidan, a sulfated polysaccharide from the brown algae Fucus vesiculosus, has diverse biological properties, including anti-inflammatory, anticoagulant and antithrombotic activity. This study analyzed the therapeutic activity of total fucoidan (TF) from F. vesiculosus and that of purified fractions (F1 and F2) on zymosan-induced arthritis. Arthritis was induced by injecting zymosan into the knee joint. Thus, three fucoidan fractions were obtained by acetone fractionation. Due to the yield obtained from F3, we used only fucoidans F1 and F2 in the induced inflammation tests. Chemical analyses and electrophoretic characterization of these fractions demonstrated that they contain polysaccharides, sulfate ester and very low protein levels. The fucoidans obtained from TF showed only an electrophoretic band in agarose gel with much lower polydispersion. The F2 fraction showed a migration between fucoidans F1 and F3. We administered TF (15, 30, 50 mg/kg I. P.), F1 or F2 (10, 25 and 50 mg/kg I. P.), diclofenac sodium (10 mg/kg I. P.), lumiracoxib (5 mg/kg O. A.) or L-NAME (30 mg/kg I. P.), 1 hour after induction of articular inflammation. We analyzed cell influx and nitrite levels in addition to performing histopathological analysis. TF (total fucoidan) at 15, 30, 50 mg/kg I. P. and its fractions (F1 and F2 at concentrations of 25 and 50 mg/kg I. P.) significantly reduced cellular influx and nitric oxide concentration. Moreover, the articular inflammation in zymosan-induced arthritis caused a progressive loss in glycosaminoglycan content. This loss decreased when TF (30 mg/kg) was administered. These data suggest that fucoidan exerts anti-inflammatory action in a zymosan-induced model of acute inflammation in rats. Taken together with the fact that these natural compounds have minimal toxicity, this may have important therapeutic implications.

A xylogalactofucan from the brown seaweed Spatoglossum schröederi stimulates the synthesis of an antithrombotic heparan sulfate from endothelial cells.

The brown seaweed Spatoglossum schröederi (Dictyotaceae) contains three main fucans (fucans A, B and C) with different mobility in electrophoresis. The fucan with highest mobility (fucan C) was precipitated with 2.0 volumes of acetone, purified using a combination of ion exchange chromatography and electrophoresis. It showed an MW of 24 kDa determined by HPLC and Sephadex G-75 chromatography and migrates as a single band in three distinct electrophoretic systems. This fucan contains fucose, xylose, galactose and sulfate in a molar ratio 1 : 0.6 : 2:2.3. The fucan has neither anticoagulant (from 10 to 100 microg) nor hemorrhagic activities (100 microg/mL). In addition, fucan C is neither cytotoxic nor cytostatic. However, fucan C (100 microg/mL) stimulated the synthesis of an antithrombotic heparan sulfate from endothelial cells of rabbit aorta. The results suggest that fucan C might be used as an antithrombotic therapeutic compound.