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Previous issue date: 2015-08-07 === Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) === Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico (CNPq) === A produ??o de nanoparticulas de prata com extratos naturais tem sido
apontada como uma excelente alternativa para potencializar ou fornecer novas
aplicabilidades aos extratos. Extratos de polissacar?deos sulfatados de algas
(ASP) apresentam propriedades farmacol?gicas, por?m h? poucos relatos da
produ??o de nanopart?culas de prata com extratos ricos em polissacar?deos
sulfatados (SPN). Assim, neste trabalho sintetizou-se SPN de algas
encontradas no Brasil: Spatoglossum schr?ederi, Dictyopteris justii, Sargassum
filipendula e Dictyota mertensii. A obten??o dos extratos ricos em
polissacar?deos ocorreu por prote?lise seguida por precipita??o com metanol. A
s?ntese das diferentes nanopart?culas ocorreu com a adi??o de solu??es de
prata 1 mM em solu??es dos diferentes polissacar?deos e mantidos em
repouso. Posteriormente as amostras foram centrifugadas e liofilizadas. A
forma??o SPN foi confirmada por espectroscopia UV/vis?vel, microscopia
eletr?nica de varredura e microscopia de for?a at?mica. O tamanho das SPN foi
de 108 ? 2 nm; 82 ? 1nm; 288 ? 52 nm; 104 ? 2 nm para S. schr?ederi; D. justii;
S. filipendula; D. mertensii, respectivamente e se manteve est?vel por catorze
meses, os potenciais zeta foram negativos e as formas das SPN foram
esf?ricas. Os resultados de diversos testes in vitro mostraram que as SPN
potencializam as atividades antioxidantes de ASP. As SPN tamb?m foram
biocompat?veis com c?lulas normais 3T3 (fibroblastos murinicos). Por outro
lado, SPN de S schr?ederi e de D. mertensii tiveram atividade citot?xica (~60%)
frente as c?lulas de melanoma mur?nico (B16F10) e acredita-se que a maior
atividade citot?xica destas SPN ocorram devido aos seus pequenos tamanhos.
SPN tamb?m tiveram grande capacidade antibacteriana. Nanopart?culas de D.
justii e S. filipendula tiveram os melhores resultados, sendo necess?rio
somente 50 ?g/mL para a morte da bact?ria E. coli e 100 ?g/mL para a morte
de S. aureus. Hipotet?za-se que esta atividade ocorra por libera??o de prata
pelas SPN. SPN tamb?m foram capazes de induzir a produ??o de ?xido n?trico
e citocinas com perfil semelhante a os seus respectivos ASP, com exce??o
para SPN de S. schr?ederi. Em geral, os resultados revelaram que a s?ntese de
SPN a partir das ASP potencializa efeitos antioxidantes, citot?xico e
antibacteriano dos ASP, al?m de apresentar o mesmo efeito imunomodulador
de seus respectivos ASP. Os dados obtidos levam a propor que a s?ntese de
SPN constituiu-se como um poss?vel mecanismo potencializador de atividades
biol?gicas. === The production of silver nanoparticle containing natural extracts has been
identified as an excellent alternative to enhance or provide new applicability for these
extracts. Sulfated polysaccharides-rich extracts (ASP) from seaweeds showed
several pharmacological properties, but there are few reports of the production of
silver nanoparticle with sulfated polysaccharides (SPN). Therefore, this paper we
synthesized SPN from seaweeds founded in Brazil: Spatoglossum
schr?ederi, Dictyopteris justii, Sargassum filipendula e Dictyota mertensii. The
obtainment of polysaccharides rich extracts it occurred by proteolysis followed by
methanol precipitation. The synthesis of various nanoparticles occurred with the
addition of silver solution 1 mM on different polysaccharides solutions and kept at
rest. Subsequently the samples were centrifuge and lyophilized. The SPN formation
was confirmed by UV/ visible spectroscopy, scanning electron microscopy and
atomic force microscopy. The size of SPN was 108 ? 2 nm; 82 ? 1nm; 288 ? 52 nm;
104 ? 2 nm for S. schr?ederi; D. justii; S. filipendula; D. mertensii, respectively. The
nanoparticules remained stable for fourteen months, the Zeta potential were negative
and forms of SPN were rounded. Data from various antioxidant in vitro tests showed
that the SPN were more effective than ASP. The SPN were also biocompatible with
the normal cells 3T3 (murine fibroblast). Moreover, SPN of S. schr?ederi and of D.
mertensii had cytotoxic activity (~60%) against melanoma cells (B16F10). We believe
that the increased of cytotoxic activity of these SPN occur due to their small size.
SPN also had great antibacterial capacity. D. justii and S. filipendula nanoparticles
had the best results, requiring only 50 mg/mL and 100 mg/mL for induces E. coli and
S. aureus death. We hypothesized that this activity occurs by release of SPN?s silver.
SPN also increase the nitric oxide and cytokines release from macrophages as
similar profile to the respective ASP, except for S. schr?ederi SPN. In general, the
results showed that SPN were more effective as antioxidant, antibacterial and
cytotoxic agents than their respective ASP, as well as, SPN have shown the same
immunomodulation effect of the respective ASP. The results lead to propose that the
SPN synthesis constituted as a possible potentiating mechanism of biological
activities of ASPs.
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