RESUMO
Structure of the fucoidan from Sargassum horneri and products of its enzymatic transformation with molecular weight over 20 kDa were investigated. Fucoidan was hydrolyzed by recombinant fucoidanase FFA1 and its fraction of higher molecular weight was fractionated using anion-exchange chromatography, resulting in three sulphated polysaccharides of various molecular weight (63-138 kDa). Their structures were analyzed using NMR spectroscopy, showing the fucoidan (ShF) to be a branched polysaccharide with the backbone consisting of the repeating â3-α-l-Fucp(2SO3-)-1â4-α-l-Fucp(2,3SO3-)-1â fragment and side chains including the α-l-Fucp-1â2-α-l-Fucp-1â or α-l-Fucp-1â3-α-l-Fucp(4SO3-)-1â fragments attached to the main chain at C4. The fragment F3 differing by molecular weight and side chain from other fucoidans fragments possessed the most significant anticancer and radiosensitizing activities.
Assuntos
Antineoplásicos/farmacologia , Células Epiteliais/efeitos dos fármacos , Polissacarídeos/farmacologia , Radiossensibilizantes/farmacologia , Sargassum/química , Proteínas de Algas/química , Antineoplásicos/química , Antineoplásicos/isolamento & purificação , Antineoplásicos/metabolismo , Biotransformação , Sequência de Carboidratos , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Sobrevivência Celular/efeitos da radiação , Relação Dose-Resposta a Droga , Células Epiteliais/patologia , Células Epiteliais/efeitos da radiação , Glicosídeo Hidrolases/química , Humanos , Hidrólise , Peso Molecular , Polissacarídeos/química , Polissacarídeos/isolamento & purificação , Polissacarídeos/metabolismo , Radiossensibilizantes/química , Radiossensibilizantes/isolamento & purificação , Radiossensibilizantes/metabolismo , Proteínas Recombinantes/química , Raios XRESUMO
Fucoidans are valuable biologically active polysaccharides of brown algae. The aim of this study was to investigate the structure of fucoidan from Sargassum feldmannii and the anticancer effects of native and modified polysaccharides from S. feldmannii and S. duplicatum. The structure of sulfated (25.3%) galactofucan SfF2 (Fuc/Galâ¯=â¯72/28â¯mol%) from S. feldmannii was investigated by NMR spectroscopy of desulfated derivative and mass spectrometry of fucoidan fragments labelled with 18O. SfF2 was shown to contain the main chain from 1,3-linked α-l-fucopyranose and ß-d-galactopyranose residues with fucose branches at C4 and C6 of galactose residues and C2 of fucose residues. The following fragments were also identified in SfF2: Fuc-(1,4)-Fuc, Gal-(1,3)-Gal, and Gal-(1,4)-Gal. The sulfate groups occupied positions C2, C3, and C4 of fucose residues and C2, C3, C4, and C6 of galactose residues. The galactofucans from S. feldmannii, S. duplicatum, and their derivatives exhibited no cytotoxicity in vitro. The native and deacetylated fucoidans (200⯵g/mL) inhibited colony formation of human colon cancer cells (DLD-1, HT-29, and HCT-116). Both desulfated fucoidans possessed weak anticancer activity.
