Avaliação química de polissacarídeos e propriedades antimelanoma da heterogalactana proveniente do macrofungo Hypsizygus marmoreus
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Data
2019-02-02
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Universidade Federal de Goiás
Resumo
Hypsizygus marmoreus, popularly known as "Bunashimeji" in Japan, is an edible mushroom highly valued for its medicinal properties. Several therapeutic effects have been reported for this species as immunomodulatory, antitumor, antiviral, cytotoxic, antifungal, antihypertensive, antioxidant, anti-inflammatory, antiproliferative, regulation of obesity and insulin resistance, antiatherosclerotic, which have been attributed to crude extracts, fractions and/or isolated compounds (proteins, lipids, polysaccharides, oligopeptides and secondary metabolites) obtained from the basidiocarp and/or mycelium and filtered from the submerged culture. Considering the diversity of polysaccharides present in each fungal species, as well as their importance in modifying the biological response, the H. marmoreus mushroom is unexplored in this area, representing an important species to be studied. For this, the aqueous and alkaline extractions were performed to obtain the polysaccharide extracts, which were purified by freezing/thawing and precipitation with Fehling's solution. The structural determination was performed by NMR spectroscopy, monosaccharide composition analysis and methylation by GC-MS and partial hydrolysis. From the cold aqueous extract was isolated a fucomannogalactan (fraction Hm-PF2AF, Hm-FMG; Mw = 17,670 Da) contained (-16)-linked galactopyranosyl main chain, partially substituted at O-2 with non-reducing ends of α-L-Fucp and -Manp; a branched α-glucan with glycosidic bonds of the type (1→4) and (1→6) (Hm-MRSF2) with a glycogen-like structure and a branched -glucan with a Glcp-(1→3)-linked backbone, partially substituted at O-6 by non-reducing ends of -Glcp (Hm-S2AF). Fractionation of the cold water soluble fraction obtained from the alkaline extract (Hm-SK) resulted in two fractions containing glycogen and a -glucan (Hm-SFK and Hm-PFK) distinct from that previously mentioned. After elimination of glycogen by amylase treatment, the fractions obtained (Hm-TASFK and Hm-TAPFK, respectively) probably consist of branched -glucans containing a main chain of β-Glcp (16)-linked, which are partially substituted in O-3. Further analysis of structural characterization (2D NMR, methylation, partial degradation of Smith, among others) should be performed to confirm the structure of -glucans isolated and other fractions obtained in this study. In order to prove the effects of polysaccharides as biological response modifiers, the purified fractions (fucomannogalactan and -glucans) of H. marmoreus were submitted to evaluation of the antitumoral activities, in collaboration with Prof. Dr. Edvaldo da Silva Trindade and Dr. Stellee M. P. Biscaia from the Cell Biology Department of the Federal University of Paraná. Preliminary results of fucomannogalactan (Hm-FMG) demonstrated that heterogalactan was not cytotoxic, nor altered cell morphology, but was able to reprogram B16-F10 murine melanoma cells by modifying colony formation ability and cell migration, without changing cellular proliferation. In view of the promising in vitro antimelanoma effects of the Hm-FMG polysaccharide, it can be suggested that these polymers are responsible for part of the therapeutic properties conferred by this macrofungus. To confirm these findings, additional assays should be performed to prove the possible antitumor effects of purified fractions and the mechanism of action of these compounds.
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Hypsizygus marmoreus, Macrofungos, Polissacarídeos, Caracterização estrutural, Atividade antitumoral, Macrofungi, Polysaccharides, Structural characterization, Antitumor activity
Citação
OLIVEIRA, R. S. Avaliação química de polissacarídeos e propriedades antimelanoma da heterogalactana proveniente do macrofungo Hypsizygus marmoreus. 2019. 100 f. Dissertação (Mestrado em Química) - Universidade Federal de Goiás, Catalão, 2019.