Polissacarídeos sulfatados de macroalgas verdes: correlação com parâmetros ambientais e obtenção de glucogalactanas sulfatadas anticoagulantes
Polysaccharides of seaweeds can have their synthesis, structure and pharmacological properties modified due to changes in environmental factors. But few algae have been analyzed in this light. The green seaweed C. cupressoides var. flabellata Børgesen is an abundant alga in the coast of Rio Grand...
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| Formato: | doctoralThesis |
| Idioma: | por |
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| Endereço do item: | https://repositorio.ufrn.br/jspui/handle/123456789/25639 |
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| Resumo: | Polysaccharides of seaweeds can have their synthesis, structure and
pharmacological properties modified due to changes in environmental factors. But few
algae have been analyzed in this light. The green seaweed C. cupressoides var.
flabellata Børgesen is an abundant alga in the coast of Rio Grande do Norte and it was
already shown that this seaweed collected at the same time in beaches with different
degree of salinity synthesized sulfated polysaccharides (PS) with different properties,
including anticoagulant activity. Therefore the objective of this study was to obtain and
characterize PS of green seaweed of the coast of Rio Grande do Norte evaluating the
influence of the collection period and environmental parameters in the chemical
composition and anticoagulant activity of PS as well as purify, characterize and
evaluate the anticoagulant potential of at least one PS of the seaweed C. cupressoides.
Initially, extracts rich in sulfated polysaccharides (ERPS) were obtained by proteolysis
followed by precipitation with methanol of the seaweed C. cupressoides collected
monthly for one year on the beach in Búzios, Nísia Floresta/RN. It was noted that there
were variations in performance of extraction, chemical composition and anticoagulant
activity of ERPS C. cupressoides according to the month of collection, with the month
of March being the one in which they obtained more anticoagulant potential of ERPS.
It is worth noting that this activity was greater than that of Clexane®, a low molecular
weight commercial heparin. When analyzing the influence of environmental factors in
the collection site in regards to performance, chemical composition and anticoagulant
activity it has been observed that there is a significant positive correlation (p < 0.05)
between the performance of the extraction of ERPS and salinity of sea water and
insolation; for the amount of sulfate it was observed a significant negative correlation
(p < 0.05) with the salinity of the seawater. The amount of total sugars had a significant
negative correlation (p < 0.05) with: total solids, sodium, chloride and insolation. Since
the month of March was the month with ERPS with more anticoagulant potential, it was
decided to purify, characterize and evaluate the PS anticoagulant potential extracted
on that month. After proteolysis and fractionation with increasing volumes of acetone
four fractions of polysaccharide C. cupressoides (CCB-0.3, CCB-0.5, CCB-1.0 e CCB2.0)
were obtained. Since the CCB-0.5 had higher anticoagulant activity, it was
submitted to a chromatography ion-exchange column and eluted in two new fractions
(FI and FII) after agarose gel electrophoresis, slide staining with toluidine blue and
discoloration it was observed the appearance of a single band on both SP which
indicates the presence of a single population of PS, which allows inferring that these
PS were purified. Analysis by high-performance liquid chromatography (HPLC)
indicate that SP FI and FII are glucogalactanas. These sulfated glucogalactans
exhibited by the intrinsic pathway anticoagulant activity (APTT assay) the extrinsic
pathway (PT test) and common pathway (TT test) of the coagulation cascade. An
interesting result was that activity in the aPTT test of sulfated glucogalactans was
similiar activity of Clexane®. In addition, these PS were able to partially inhibit
thrombin. This is an indicative that the PS C. cupressoides may be acting on various
proteases of the coagulation cascade. But more studies are needed to explain in detail
which are the targets of action of these polymers. Finally, we analyzed the influence of
the period of collection and environmental factors in ERPS of other green seaweeds
RN coast (Caulerpa prolifera, Caulerpa racemosa var. occidentalis, Caulerpa
sertularioides and Codium isthmocladum) also collected monthly for one year on the
beach of Búzios, Nísia Floresta/RN; and it was observed that, like the C. cupressoides,
there were variations in the performance, chemical composition and anticoagulant activity for ERPs green seaweeds C. prolifera, C. racemosa, C. sertularioides and C.
isthmocladum. However, an interesting fact is that each alga responds differently to
environmental conditions of the collection site. These data indicate that depending on
the time of the year that the algae are collected, the PS extracted from these species
of algae may have their chemical structures affected hence its biological activity may
be different. These types of studies lead to the clarification of which would be the best
conditions to obtain the PS with the structural and biological characteristics of interest,
which is essential for the use of these polymers in the industry. |
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