Banca de DEFESA: PABLO DE CASTRO SANTOS

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
DISCENTE : PABLO DE CASTRO SANTOS
DATA : 30/08/2016
HORA: 08:00
LOCAL: Anfiteatro das Aves - Centro de Biociências
TÍTULO:

OBTAINING sulfated polysaccharides SEAWEED RED EDIBLE Gracilaria birdiae AND INFLUENCE ON FORMATION AND MORPHOLOGY OF CALCIUM OXALATE CRYSTALS (CaOx)

PALAVRAS-CHAVES:

Red algae, sulfated galactans, kidney stones, nephrolithiasis.

PÁGINAS: 107
GRANDE ÁREA: Ciências Biológicas
ÁREA: Bioquímica
RESUMO:

The urolithiass disease affects approximately 10% of the world's population and is strongly associated calcium oxalate crystals. Until now, there is not an efficient compound that can be used to prevent this disease. However, some sulfated polysaccharides (SP) from brown seaweeds exhibited an ability to inhibit the formation of calcium oxalate crystals and change the morphology in vitro. SP from the red seaweed Gracilaria birdiae have important biological activities, but they have not been evaluated as inhibitor of CaOx crystals formation. This study aimed to obtain SP from this seaweed and evaluate their effect on CaOx crystals formation. Thus, sulfated polysaccharide-rich extract (EC) was obtained using alkaline extraction, sonication, proteolytic digestion followed by ethanol precipitation. This extract was fractionated into five fractions (F-0.25; F-0.5; F, 0.75; F-1.0; F-1.25) by DEAE-cellulose ion-exchange chromatography. Agarose gel electrophoresis, infrared and chemical analysis showed that these fractions contain the same pool of sulfated galactose-rich polysaccharides.   F-0.25; F-0.5; F, 0.75; F-1.0 were able to inhibit important formation steps of the CaOx crystals, as nucleation and aggregation, we highlight F-0.25 that promoted the highest inhibition of nucleation in 76.92% and aggregation in 68.57%.  The F- 0.5 and F-0.25 fractions were able to reduce approximately 7 and 6 times, respectively, the number of these CaOx monohydrated crystals (COM) formed in vitro whereas F-0.75 and F-1.0 fractions reduced this number only 1.5 times. Among all the tested fractions, F-0.75 fraction induce the formation of crystals COM about 6 times smaller than the control. The morphology of CaOX crystals was mainly affected by the samples EC, F-0.25; F-0.5 and F-0.75, they promoted the most discordant variations in the control. The analysis of the zeta potential (ζ) of the crystals formed in the presence of the samples was found an increase of negative charges on their surfaces. Through the images obtained by fluorescence microscopy revealed that the PS are distributed homogeneously in the dehydrated crystals (COD) and peripherally in COM. The data obtained by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) revealed wide va riations in the distribution of oxygen and calcium atoms on the surface of the crystals in the presence of F-0.25 and F-0.5. The kidney cells HEK-293, MDCK and 786-0 showed low toxicity in the presence of EC and fractions F-0.25; F-0.5; F, 0.75. These samples protected kidney MDCK cells against damage caused by H₂O₂ and CaOx. Finally, the MDCK cells treated beforehand and concomitant with both F-0.25 and F-0.5 in the presence of H₂O₂ and CaOx, reduced the activity of superoxide dismutase and catalase enzymes. Overall, the data showed that PS G. birdiae may be potential pharmacological targets for preventive, therapeutic and repairing damage caused by urolithiasis. However, it is important that to make set in vivo experiments, as well as, experiments to elucidate the precise mechanism of action by which these PS protect the H₂O₂ damage on cells.

MEMBROS DA BANCA:
Externo ao Programa - 1221519 - DÁRLIO INÁCIO ALVES TEIXEIRA
Externo ao Programa - 2524706 - GIULIANNA PAIVA VIANA DE ANDRADE SOUZA
Externo à Instituição - JAIR ADRIANO KOPKE DE AGUIAR - UFJF
Presidente - 046.477.204-46 - LEANDRO SILVA COSTA - IFRN
Externo à Instituição - VALQUIRIA PEREIRA DE MEDEIROS - UFJF