Banca de DEFESA: MARILIA MEDEIROS FERNANDES DE NEGREIROS

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
DISCENTE : MARILIA MEDEIROS FERNANDES DE NEGREIROS
DATA : 26/09/2019
HORA: 14:00
LOCAL: Sala Carl Peter von Dietrich - Departamento de Bioquímica
TÍTULO:

Chemical modifications of polysaccharides of the algae Lobophora variegata and Dictyota mertensii enhancing their pharmacological activities.

PALAVRAS-CHAVES:

neutral polysaccharide, sulfated polysaccharide, brown algae, cold plasma

PÁGINAS: 193
GRANDE ÁREA: Ciências Biológicas
ÁREA: Bioquímica
SUBÁREA: Química de Macromoléculas
RESUMO:

Laminarin (1,3-β-glucan) and fucan (sulfated polysaccharide consisting of sulfated L-fucose) are synthesized by brown seaweeds and have several pharmacological activities described. However, polysaccharides and their activities can be modified, promoting empowerment or not. Thereunto, various techniques are used, such as those called green methods. Therefore, this work aimed to extract from the brown seaweed Dictyota mertensii (rich source of fucanas) and Lobophora variegata (rich source of laminarines) these two types of polysaccharides from brown seaweed and modify them using green methods. In case of fucana, produce silver nanoparticles. In case of lamanirine, add functional groups (sulfate, carboxyl, or gallic acid). Algae were collected at Pirangi beach, Natal, RN, washed and submitted to proteolysis for 18 h. Using acetone differential fractionation and molecular mass separation techniques, a 12.4 kDa laminarin was obtained. The fucana was obtained after proteolysis and precipitation with methanol. Physicochemical analysis shows laminarin consists only of glucose and fucan of more than four different types of monosaccharides, besides fucose. Dielectric barrier discharge (DBD), sulfation and galification techniques were used to obtain modified laminarins called LMC, LMS and LMG. The modifications promoted different amounts of insertion of the functional groups: with LMS 1.4% sulfate was observed, with LMG 1.5% of gallic acid and 11.7% of uronic acids. The modification that most enhanced the antioxidant activities of laminarins was galification, therefore, LM and LMG had their structure elucidated by NMR. The data obtained by NMR analysis corroborate with the previous data proving the structure of laminarine in LM and gallified laminarine in LMG. LM and LMG were not cytotoxic and did not alter the cell cycle of MDCK cells compared to the control. In parallel, it was possible to obtain silver nanoparticles with fucan, which was called NF. The seventh day was the optimal synthesis day for this particle, whose size was ~ 104 nm. The NF had a round shape and very homogeneous size distribution, stability for 16 months and showed a higher antitumor activity (1mg / mL) compared to fucan. NF also had better antibacterial activity than native fucan and immunomodulatory activities (nitric oxide production and cytokine production) had similar results when compared to NF with native fucans. In general, it was observed that the gallification was to improve chemical modification in L. variegata laminarins and the NF potentiated the pharmacological activities of the fucans.

 

MEMBROS DA BANCA:
Presidente - 2195251 - HUGO ALEXANDRE DE OLIVEIRA ROCHA
Interno - 046.477.204-46 - LEANDRO SILVA COSTA - IFRN
Externa ao Programa - 2477216 - NAISANDRA BEZERRA DA SILVA FARIAS
Externa à Instituição - CINTHIA BEATRICE DA SILVA TELLES - IFRN
Externa à Instituição - MARIANA SANTANA SANTOS PEREIRA DA COSTA - IFRN
Externo à Instituição - ÉDER GALINARI FERREIRA - UFRPE