RESUMEN
Several polysaccharides are considered to be "biological response modifiers" (BRM) - these refer to biomolecules that augment immune responses and can be derived from a variety of sources. Microalgae produce a diverse range of polysaccharides and could be an excellent source of BRM. Here, we describe the chemical structure and biological activity of water-soluble polysaccharide isolated from the marine diatom Conticribra weissflogii. Using chemical and NMR spectroscopic methods, the polysaccharide was identified as a (1 â 3)-linked ß-D-glucan with a low proportion of C-6 substitution by single ß-glucose units. The biological activity of this low molecular weight ß-glucan (11.7 kDa) was investigated with respect to glioblastoma cell lines (U87 MG and U251) and macrophages (RAW 264.7). We observed that this ß-D-glucan did not exhibit cytotoxic activity against glioblastoma cells, but did enhance the phagocytic activity of macrophages, suggesting that it possesses immunomodulatory properties.
Asunto(s)
Diatomeas , Glioblastoma , beta-Glucanos , Humanos , Glucanos/química , Polisacáridos/química , beta-Glucanos/química , Factores InmunológicosRESUMEN
Syzygium jambos is an Indo-Malaian found in many tropical countries and it is mainly composed of carbohydrates. Fraction PF-WSP and SF-WSP were obtained by aqueous extraction followed by Fehling's treatment. Monosaccharide analysis showed that fraction PF-WSP has a high content of uronic acids (90%) and fraction SF-WSP presented mainly galactose (39.1%) and arabinose (34.2%), as neutral sugars and 9% of galacturonic acid. The presence of type II arabinogalactan in SF-WSP was evidenced by methylation analysis and 13C/1H HSQC NMR experiments. Immunomodulating properties of SF-WSP was investigated. It decreases THP-1 macrophage viability at the highest concentration tested (200µg/mL). We then tested non-cytotoxic concentrations of SF-WSP on THP-1 cytokine production in the presence and absence of LPS. The results showed that SF-WSP increased TNF-α, IL-1ß and IL-10 secretion in a concentration-dependent manner as well as attenuated the inflammatory response induced by LPS at the highest concentration (100µg/mL). These results contribute to elucidate the effects of fruit pectic polysaccharides on immune cells.
Asunto(s)
Galactanos/química , Factores Inmunológicos/química , Extractos Vegetales/química , Syzygium/química , Arabinosa/química , Carbohidratos/química , Citocinas/genética , Citocinas/inmunología , Galactanos/aislamiento & purificación , Galactanos/farmacología , Galactosa/química , Ácidos Hexurónicos/química , Humanos , Factores Inmunológicos/aislamiento & purificación , Factores Inmunológicos/farmacología , Monocitos/efectos de los fármacos , Monocitos/inmunología , Ácidos Urónicos/químicaRESUMEN
Jambo is a tropical fruit cultivated in Southeast Asia and tropical regions of America and Africa. After extraction, its polysaccharides were structurally characterized. Water soluble polysaccharides (WSP) were composed of GalA:Ara:Gal:Glc:Rha in 51:22:16:5:6â¯molar ratio, indicating the presence of pectic polysaccharides. Methylation analysis and NMR spectroscopy indicated the presence of homogalacturonan (HG), type II arabinogalactan and type I rhamnogalacturonan (RG-I). The HG/RG-I ratio was 88%, indicating greater amounts of smooth than hairy pectic regions. Hemicellulosic polysaccharides were extracted from the residue and fractionated by freeze-thaw procedure in two fractions (ASP-S and ASP-I). ASP-S was composed of Glc:Gal:Xyl:Ara:Man:Fuc:UA in a 45:16:20:3:8:5:2â¯molar ratio. Methylation analysis and 13C NMR spectroscopy indicated xyloglucan, xylan and mannan. Their relative proportion estimated on sugar linkage was 89%, 6% and 3%, respectively. ASP-I was composed mainly of xylose (99.5%) and its 13C NMR indicated a linear (1â¯ââ¯4)-ß-D-xylan. The biological activity of WSP was tested in Ehrlich tumor-bearing mice. After 21â¯days of oral treatment, the doses of 150 and 250â¯mg/kg WSP reduced expressively the tumor growth, similarly to the positive control methotrexate, and improved the body weight of tumor-bearing mice. Further studies are necessary to investigate the mechanisms of the WSP antitumor effect.