Navegando por Palavras-chave "Brown algae"
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- ItemAcesso aberto (Open Access)Can macroalgae provide promising anti-tumoral compounds? A closer look at Cystoseira tamariscifolia as a source for antioxidant and anti-hepatocarcinoma compounds(Peerj Inc, 2016) Vizetto-Duarte, Catarina; Custodio, Luisa; Acosta, Gerardo; Lago, Joao H. G.M[UNIFESP]; Morais, Thiago R. [UNIFESP]; de Sousa, Carolina Bruno; Gangadhar, Katkam N.; Rodrigues, Maria Joao; Pereira, Hugo; Lima, Raquel T.; Helena Vasconcelos, M.; Barreiro, Luisa; Rauter, Amelia P.; Albericioi, Fernando; Varela, JoaoMarine organisms are a prolific source of drug leads in a variety of therapeutic areas. In the last few years, biomedical, pharmaceutical and nutraceutical industries have shown growing interest in novel compounds from marine organisms, including macroalgae. Cystoseira is a genus of Phaeophyceae (Fucales) macroalgae known to contain bioactive compounds. Organic extracts (hexane, diethyl ether, ethyl acetate and methanol extracts) from three Cystoseira species (C. humilis, C. tamariscifolia and C. usneoides) were evaluated for their total phenolic content, radical scavenging activity against 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'- azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radicals, and antiproliferative activity against a human hepatocarcinoma cell line (HepG2 cells). C. tamariscifolia had the highest TPC and RSA. The hexane extract of C. tamariscifolia (CTH) had the highest cytotoxic activity (IC50 = 2.31 mu g/mL), and was further tested in four human tumor (cervical adenocarcinoma HeLa; gastric adenocarcinoma AGS; colorectal adenocarcinoma HCT-15; neuroblastoma SH-SY5Y), and two non-tumor (murine bone marrow stroma S17 and human umbilical vein endothelial HUVEC) cell lines in order to determine its selectivity. CTH strongly reduced viability of all tumor cell lines, especially of HepG2 cells. Cytotoxicity was particularly selective for the latter cells with a selectivity index = 12.6 as compared to non-tumor cells. Incubation with CTH led to a 2-fold decrease of HepG2 cell proliferation as shown by the bromodeoxyuridine (BrdU) incorporation assay. CTH-treated HepG2 cells presented also pro-apoptotic features, such as increased Annexin Wpropidium iodide (PI) binding and dose-dependent morphological alterations in DAPI-stained cells. Moreover, it had a noticeable disaggregating effect on 3D multicellular tumor spheroids. Deme boxy cystoketal chromane, a derivative of the meroditerpenoid cystoketal, was identified as the active compound in CTH and was shown to display selective in vitro cYtotoxicitY towards HepG2 cells.
- ItemAcesso aberto (Open Access)Heterofucans from Dictyota menstrualis have anticoagulant activity(Associação Brasileira de Divulgação Científica, 2004-02-01) Albuquerque, Ivan Rui Lopes; Queiroz, Karla Cristiana Souza; Alves, Luciana Guimarães [UNIFESP]; Santos, Elizeu Antunes dos [UNIFESP]; Leite, Edda Lisboa [UNIFESP]; Rocha, Hugo Alexandre Oliveira [UNIFESP]; Universidade Federal do Rio Grande do Norte Departamento de Bioquímica Laboratório de Biotecnologia de Polímeros Naturais; Universidade Federal do Rio Grande do Norte Departamento de Bioquímica Laboratório de Glicobiologia; Universidade Federal de São Paulo (UNIFESP)Fucan is a term used to denote a family of sulfated L-fucose-rich polysaccharides which are present in the extracellular matrix of brown seaweed and in the egg jelly coat of sea urchins. Plant fucans have several biological activities, including anticoagulant and antithrombotic, related to the structural and chemical composition of polysaccharides. We have extracted sulfated polysaccharides from the brown seaweed Dictyota menstrualis by proteolytic digestion, followed by separation into 5 fractions by sequential acetone precipitation. Gel electrophoresis using 0.05 M 1,3-diaminopropane-acetate buffer, pH 9.0, stained with 0.1% toluidine blue, showed the presence of sulfated polysaccharides in all fractions. The chemical analyses demonstrated that all fractions are composed mainly of fucose, xylose, galactose, uronic acid, and sulfate. The anticoagulant activity of these heterofucans was determined by activated partial thromboplastin time (APTT) using citrate normal human plasma. Only the fucans F1.0v and F1.5v showed anticoagulant activity. To prolong the coagulation time to double the baseline value in the APTT, the required concentration of fucan F1.0v (20 µg/ml) was only 4.88-fold higher than that of the low molecular weight heparin Clexane® (4.1 µg/ml), whereas 80 µg/ml fucan 1.5 was needed to obtain the same effect. For both fucans this effect was abolished by desulfation. These polymers are composed of fucose, xylose, uronic acid, galactose, and sulfate at molar ratios of 1.0:0.8:0.7:0.8:0.4 and 1.0:0.3:0.4:1.5:1.3, respectively. This is the fist report indicating the presence of a heterofucan with higher anticoagulant activity from brown seaweed.
- ItemSomente MetadadadosA non-anticoagulant heterofucan has antithrombotic activity in vivo(Georg Thieme Verlag Kg, 2008-06-01) Barroso, Edjane Maria de Azevedo; Costa, Leandro Silva; Medeiros, Valquiria Pereira de [UNIFESP]; Cordeiro, Sara Lima; Costa, Mariana Santana Santos Pereira; Franco, Celia Regina Cavichiolo; Nader, Helena Bonciani [UNIFESP]; Leite, Edda Lisboa; Rocha, Hugo Alexandre de Oliveira; Univ Fed Rio Grande do Norte; Universidade Federal de São Paulo (UNIFESP); Univ Fed ParanaFucan is a term used to denominate a family of sulfated L-fucose-rich polysaccharides. the brown alga Spatoglossum schroederi(Dictyotaceae) has three heterofucans namely fucan A, B and C. the 21 kDa fucan A is composed of a core of a beta (1-3) glucuronic acid-containing oligosaccharide of 4.5 kDa with branches at C4 of the fucose chains a (1-3) linked. the fucose is mostly substituted at C4 with a sulfate group and at C2 with chains of beta (1-4) xylose. This fucan has neither anticoagulant (from from 0.1 to 100 mu g) nor hemorrhagic activities (from 50 to 800 mu g/mL). the antithrombotic test in vivo showed that fucan A has no activity in any of the concentrations (from 0.2 to 20 mu g/g/day) tested 1 h after polysaccharide administration. However, when fucan A was injected endovenously 24 h before the ligature of the venae cavae, we observed a dose-dependent effect, reaching saturation at around 20 mu g/g of rat weight. in addition, this effect is also time-dependent, reaching saturation around 16 h after fucan administration. in addition, regardless of the administration route, fucan A displayed antithrombotic activity. the exception was the oral pathway. of particular importance was the finding that fucan A stimulates the synthesis of an antithrombotic heparan sulfate from endothelial cells like heparin. the hypothesis has been raised that the in vivo antithrombotic activity of fucan A is related to the increased production of this heparan. Taken together with the fact that the compound is practically devoid of anticoagulant and hemorrhagic activity, the data suggest that it may be an ideal antithrombotic agent in vivo.
- ItemAcesso aberto (Open Access)Partial characterization and anticoagulant activity of a heterofucan from the brown seaweed Padina gymnospora(Associação Brasileira de Divulgação Científica, 2005-04-01) Silva, T.m.a.; Alves, L.g. [UNIFESP]; Queiroz, K.c.s. de; Santos, M.g.l.; Marques, C.t.; Chavante, Suely Ferreira [UNIFESP]; Rocha, Hugo Alexandre Oliveira [UNIFESP]; Leite, E.l.; Universidade Federal do Rio Grande do Norte Departamento de Bioquímica Laboratório de Glicobiologia; Universidade Federal do Rio Grande do Norte Departamento de Bioquímica Laboratório de Biotecnologia de Polímeros Naturais; Universidade Federal de São Paulo (UNIFESP)The brown algae Padina gymnospora contain different fucans. Powdered algae were submitted to proteolysis with the proteolytic enzyme maxataze. The first extract of the algae was constituted of polysaccharides contaminated with lipids, phenols, etc. Fractionation of the fucans with increasing concentrations of acetone produced fractions with different proportions of fucose, xylose, uronic acid, galactose, and sulfate. One of the fractions, precipitated with 50% acetone (v/v), contained an 18-kDa heterofucan (PF1), which was further purified by gel-permeation chromatography on Sephadex G-75 using 0.2 M acetic acid as eluent and characterized by agarose gel electrophoresis in 0.05 M 1,3 diaminopropane/acetate buffer at pH 9.0, methylation and nuclear magnetic resonance spectroscopy. Structural analysis indicates that this fucan has a central core consisting mainly of 3-ß-D-glucuronic acid 1-> or 4-ß-D-glucuronic acid 1 ->, substituted at C-2 with alpha-L-fucose or ß-D-xylose. Sulfate groups were only detected at C-3 of 4-alpha-L-fucose 1-> units. The anticoagulant activity of the PF1 (only 2.5-fold lesser than low molecular weight heparin) estimated by activated partial thromboplastin time was completely abolished upon desulfation by solvolysis in dimethyl sulfoxide, indicating that 3-O-sulfation at C-3 of 4-alpha-L-fucose 1-> units is responsible for the anticoagulant activity of the polymer.