Navegando por Autor "Melo-Silveira, Raniere Fagundes"

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Antioxidant sulfated polysaccharide from edible red seaweed Gracilaria birdiae is an inhibitor of calcium oxalate crystal formation
(MDPI, 2020-04-28) Oliveira, Leticia Castelo Branco Peroba; Queiroz, Moacir Fernandes; Fidelis, Gabriel Pereira; Melo, Karoline Rachel Teodosio; Câmara, Rafael Barros Gomes da; Alves, Monique Gabriela das Chagas Faustino; Costa, Leandro Silva; Teixeira, Dárlio Inácio Alves; Melo-Silveira, Raniere Fagundes; Rocha, Hugo Alexandre de Oliveira
The genus Gracilaria synthesizes sulfated polysaccharides (SPs). Many of these SPs, including those synthesized by the edible seaweed Gracilaria birdiae, have not yet been adequately investigated for their use as potential pharmaceutical compounds. Previous studies have demonstrated the immunomodulatory effects of sulfated galactans from G. birdiae. In this study, a galactan (GB) was extracted from G. birdiae and evaluated by cell proliferation and antioxidant tests. GB showed no radical hydroxyl (OH) and superoxide (O2−) scavenging ability. However, GB was able to donate electrons in two further different assays and presented iron- and copper-chelating activity. Urolithiasis affects approximately 10% of the world’s population and is strongly associated with calcium oxalate (CaOx) crystals. No efficient compound is currently available for the treatment of this disease. GB appeared to interact with and stabilize calcium oxalate dihydrate crystals, leading to the modification of their morphology, size, and surface charge. These crystals then acquired the same characteristics as those found in healthy individuals. In addition, GB showed no cytotoxic effect against human kidney cells (HEK-293). Taken together, our current findings highlight the potential application of GB as an antiurolithic agent
Chitooligosaccharides antagonize the cytotoxic effect of glucosamine
(Springer, 2012-10-02) Santos, Everaldo Silvino dos; Assis, Cristiane Fernandes de; Costa, Leandro Silva; Melo-Silveira, Raniere Fagundes; Oliveira, Ruth Medeiros; Pagnoncelli, Maria Giovana Binder; Rocha, Hugo Alexandre Oliveira; Macedo, Gorete Ribeiro de
Chitooligosaccharides (COS) are partially hydrolyzed compounds derived from chitosan that exhibit a number of biological activities, including antitumor, antibacterial and antifungal properties. In this work, we examined the cytotoxicity of pure COS and oligomers A, B and C (solutions composed of different amounts of COS) produced by enzymatic hydrolysis using a crude enzyme extract produced by the fungus Metarhrizium anisopliae. The antiproliferative effect of these molecules was analyzed using tumor cell lines (HepG2 and HeLa cells) and in a normal cell line (3T3). The antioxidant activity was analyzed in several in vitro experiments. Glucosamine showed higher toxicity (approximately 92%) to all cell lines studied. However, the oligomers obtained after hydrolysis demonstrated no toxic effects on the normal cells (3T3). Furthermore, we showed that a small amount of other COS can decrease the cytotoxic effect of glucosamine against 3T3 cells, indicating that glucosamine could be used as an antitumor drug in the presence of other COS. In addition, different effects were found in antiproliferative assays, which depended on the COS composition in the oligomers (A, B and C), showing that a combination of them may be essential for developing antineoplastic drugs. Superoxide anion scavenging was the main antioxidant activity demonstrated by the COS and oligomers. This activity was also dependent on the oligomer composition of the chitosan hydrolysates. Further work will identify the ideal proportions of COS and glucosamine for maximizing the effects of these biological activities
Cytotoxicity of chitosan oligomers produced by crude enzyme extract from the fungus metarhizium anisopliae in hepg2 and hela cells
(Hilaris Publisher, 2012) Santos, Everaldo Silvino dos; Assis, Cristiane Fernandes de; Melo-Silveira, Raniere Fagundes; Oliveira, Ruth Medeiros de; Costa, Leandro Silva; Rocha, Hugo Alexandre de Oliveira; Macedo, Gorete Ribeiro de
Chitooligosaccharides exhibit biological activities, including antitumor, antimicrobial and antioxidant. In this study we used a mixture of chitooligosaccharides produced by enzymatic hydrolysis in two tumor cell lines and assessed the cell proliferation and cytotoxicity of these compounds. The proliferation of HeLa cells was inhibited around by 60%
Heterofucan from Sargassum filipendula induces apoptosis in HeLa cells
(MDPI, 2011-04-14) Costa, Leandro Silva; Telles, Cinthia Beatrice Silva; Oliveira, Ruth Medeiros; Nobre, Leonardo Thiago Duarte Barreto; Dantas-Santos, Nednaldo; Câmara, Rafael Barros Gomes da; Costa, Mariana Santana Santos Pereira; Almeida-Lima, Jailma; Melo-Silveira, Raniere Fagundes; Albuquerque, Ivan Rui Lopes; Leite, Edda Lisboa; Rocha, Hugo Alexandre de Oliveira
Fucan is a term used to denominate a family of sulfated polysaccharides rich in sulfated L-fucose. Heterofucan SF-1.5v was extracted from the brown seaweed Sargassum filipendula by proteolytic digestion followed by sequential acetone precipitation. This fucan showed antiproliferative activity on Hela cells and induced apoptosis. However, SF-1.5v was not able to activate caspases. Moreover, SF-1.5v induced glycogen synthase kinase (GSK) activation, but this protein is not involved in the heterofucan SF-1.5v induced apoptosis mechanism. In addition, ERK, p38, p53, pAKT and NFκB were not affected by the presence of SF-1.5v. We determined that SF-1.5v induces apoptosis in HeLa mainly by mitochondrial release of apoptosis-inducing factor (AIF) into cytosol. In addition, SF-1.5v decreases the expression of anti-apoptotic protein Bcl-2 and increased expression of apoptogenic protein Bax. These results are significant in that they provide a mechanistic framework for further exploring the use of SF-1.5v as a novel chemotherapeutics against human cervical cancer
A low-molecular-weight galactofucan from the seaweed, Spatoglossum schröederi, binds fibronectin and inhibits capillary-like tube formation in vitro
(Elsevier, 2018-05) Menezes, Maira Maria; Nobre, Leonardo Thiago Duarte Barreto; Rossi, Gustavo Rodrigues; Almeida-Lima, Jailma; Melo-Silveira, Raniere Fagundes; Franco, Celia Regina Cavichiolo; Trindade, Edvaldo Silva; Nader, Helena Bonciani; Rocha, Hugo Alexandre de Oliveira
A low-molecular-weight (LMW) heterofucan (designated fucan B) was obtained from the brown seaweed, Spatoglossum schröederi, and its activity as an inhibitor of capillary-like tube formation by endothelial cells (ECs) was analyzed. Chemical, infrared and electrophoretic analyses confirmed the identity of fucan B. In contrast to other LMW fucans, fucan B (0.012–0.1 mg/mL) inhibited ECs capillary-like tube formation in a concentrationdependent manner. In addition, fucan B (0.01–0.05 mg/mL) did not affect ECs proliferation. Fucan B also inhibited ECs migration on a fibronectin-coated surface, but not on laminin- or collagen-coated surfaces. Biotinylated fucan B was used as a probe to identify its localization. Confocal microscopy experiments revealed that biotinylated fucan did not bind to the cell surface, but rather only to fibronectin. Our findings suggest that fucan B inhibits ECs capillary-like tube formation and migration by binding directly to fibronectin and blocking fibronectin sites recognized by cell surface ligands. However, further studies are needed to evaluate the in vivo effects of fucan B

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Navegando por Autor "Melo-Silveira, Raniere Fagundes"