Banca de QUALIFICAÇÃO: KAROLINE RACHEL TEODOSIO DE MELO

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
DISCENTE : KAROLINE RACHEL TEODOSIO DE MELO
DATA : 15/06/2018
HORA: 13:00
LOCAL: Anfiteatro dos peixes
TÍTULO:

OBTAINING SULPHATATED POLYSACCHARIDES FROM BROWN SEAWEES Dictyopteris justii AND ITS ACTION AS PROTECTOR AGENTS AGAINST INJURY CAUSED BY OXIDATIVE STRESS AND CALCIUM OXALATE CRYSTALS IN KIDNEY CELLS

PALAVRAS-CHAVES:

fucana; glucan; urolithiasis, bioactive polysaccharides.

PÁGINAS: 96
GRANDE ÁREA: Ciências Biológicas
ÁREA: Bioquímica
RESUMO:

Oxalate crystals are the main components of urinary calculi and these are closely related to oxidative stress in the pathophysiological condition of urolithiasis. Because of this, recent studies have looked for components that are capable of inhibiting this phenomenon. Studies with sulphated polysaccharides from brown algae Dictyopteris justii have shown that they are potent antioxidants, in addition to inhibiting the formation of these crystals in vitro. In the present study, four fractions rich in sulphated polysaccharides (DJ-0.3v, DJ-0.4v, DJ-0.5v, and DJ-1.2v) were obtained by proteolysis followed by sequential precipitation with acetone. The chemical analyzes showed that D. justii synthesizes populations of different sulfated polysaccharides. The first one found in DJ-0.3v is rich in glucose, xylose and glucuronic acid and shows traces of fucose; the second (DJ-0.4v), which has as differential large amounts of fucose; the two populations found in DJ-0.5v and DJ-1.2v only exhibit glucose and fucose traces, but differ by the amount of sulfate ions. All the sulfated polysaccharides presented CAT activity and modified the morphology of the calcium oxalate crystals formed in vitro, proving the identity of these biomolecules. The cytotoxicity study in HEK-293 and MDCK showed that DJ-0.3ve DJ-0.4v fractions were only cytotoxic at concentrations above 2mg / mL and DJ-0.5ve DJ-1.2v glucans were not cytotoxic at any of the concentrations studied. The protective and repairing effect of these polysaccharides was also observed. The prophylactic treatment of all sulfated polysaccharides in HEK-293 cells up to the maximum concentration of 1mg / mL seems to maintain cell viability against the damage caused by hydrogen peroxide in human renal embryonic cells. On the other hand, with the exception of the DJ-0.3v fraction all fractions had a repairing effect on the cells, with emphasis on the DJ-0.5v fraction, whose treatment maintained the highest number of viable cells in both processes. In dog kidney cells (MDCK), the prophylactic effect was also verified and it was found that only treatments with DJ 0.4 and DJ 0.5 were able to protect cells against damage. Possibly, these polysaccharides act by increasing the expression of antioxidant enzymes or acting together with them, since they are located in the perinuclear region. In addition, they decrease the expression of osteocalcin, a marker of bone differentiation. The data obtained lead us to propose that these polysaccharides are promising agents for use in the treatment of urolithiasis.

MEMBROS DA BANCA:
Presidente - 3315429 - LUCIANA GUIMARAES ALVES FILGUEIRA
Externo ao Programa - 2962496 - RAFAEL BARROS GOMES DA CAMARA
Externo à Instituição - LEONARDO THIAGO DUARTE BARRETO NOBRE - UFRN