Banca de DEFESA: ALMINO AFONSO DE OLIVEIRA PAIVA
Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.DISCENTE : ALMINO AFONSO DE OLIVEIRA PAIVA
DATA : 29/07/2016
HORA: 08:30
LOCAL: Sala Carl Peter von Dietrich
TÍTULO:
Prospection of bioactive polysaccharides from seaweed Lobophora variegata and structural elucidation of one of its β-glucans
PALAVRAS-CHAVES:
β-glucan, chelation of metals, immunomodulator, antiproliferative.
PÁGINAS: 122
GRANDE ÁREA: Ciências Biológicas
ÁREA: Bioquímica
SUBÁREA: Química de Macromoléculas
ESPECIALIDADE: Glicídeos
RESUMO:
Seaweeds are important sources of neutral and negative polysaccharides with important industrial and pharmacological potential. The brown macroalgae Lobophora variegata is known for presenting sulfated polysaccharides (heterofucans) and neutral (laminarins). In this work, it is shown getting 6 polysaccharide fractions (F0.3, F0.5, F0.8, F1, F1.5 and F2). From the data of physicochemical characterization of fractions, chose to F1 for purification of its polysaccharide components. Liquid chromatography of molecular exclusion analysis carried observation that F1 shows polysaccharide of low (~ 5 kDa) to high (> 100 kDa) molecular mass. These components were separated according to their molecular mass, using separation by molecular size devices. Thus, there was obtained subfractions with an average polysaccharide size of 5, 20, 40, 75 and above 100 kDa, named F1-5, F1-20, F1-40. F1-75 and F1>100 kDa, respectively. These subfractions were analyzed physico-chemically by agarose gel electrophoresis, high-performance liquid chromatography, as by analysis of their antioxidant, immunomodulatory and cytotoxic / antiproliferative properties. As a result, we detected a total sugar content above 55% in all subfractions, since proteins and phenolic compounds were observed. The fractions F1-5, F1-20 and F1-40 showed only glucose (glucans), as F1-75 and F1> 100 exhibit glucose, galactose and fucose (heterofucans). All subfractions showed chelating activity of metals, but only F1-75 and F1>100 were more effective in sequestering radicals. The production / release of nitric oxide (NO) by RAW cells was increased only in the presence F1-5 (10 µM, p <0.05), F1-75 (10 µM, p<0.001) and, especially, F1>100 (10 µM, p <0.001) whose presence has increased by about 12 times the amount of NO. However, when these cells were activated with LPS only F1-20 and F1>100 (10 µM) (p<0.001) yielded production / release of NO. The other fractions did not interfere in the LPS action. Only F1-5 and F1>100 stimulated the production / release of cytokines. Only F1>100 (10 µM) was cytotoxic to line 3T3 (fibroblast) (p<0.01). None of subfractions showed cytotoxicity effect to cell line RAW 264.7 (macrophages) or tumor cell line Hep-G2 (hepatocellular carcinoma). On the other hand, only F1-40 did not showed cytotoxic activity (p>0.05) against 786-0 renal carcinoma cells. The highest cytotoxicity values were obtained with the subfraction F1-20, in the case against B16F10 cells (melanoma). Flow cytometry data indicate that this subfraction promotes stopping of cells in the G1 phase of the cell cycle (10 µM, p<0.01). Nuclear magnetic resonance analysis led to the proposal that F1-20 is a β-glucan formed by β-(1à3) glucosides with branches, comprising a glucose residue at position 6. The ratio is nine glucose residues 1,3 connected to each branching point. The data point F1-20, being an antioxidant, immunomodulating and cytotoxic as a compound pluripotent whose potential should be further investigated.
MEMBROS DA BANCA:
Externo à Instituição - CELINA MARIA PINTO GUERRA DORE - F.M.Nassau
Externo à Instituição - IVAN RUI LOPES DE ALBUQUERQUE - SECD-10DIRED
Presidente - 046.477.204-46 - LEANDRO SILVA COSTA - IFRN
Externo à Instituição - LEONARDO THIAGO DUARTE BARRETO NOBRE - UFRN
Externo à Instituição - RANIERE FAGUNDES DE MELO SILVEIRA - UFRN