Institute of Chemistry, Center for Glycomics, Slovak Academy of Sciences, Dúbravská cesta 9, 845 38 Bratislava, Slovakia.
Institute of Botany, National Centre of Competence, Academy of Sciences of the Czech Republic, Dukelská 135, CZ-37982 Třeboň, Czech Republic.
Carbohydr Polym. 2022 Jan 15;276:118801. doi: 10.1016/j.carbpol.2021.118801. Epub 2021 Oct 22.
Cyanobacteria produce a wide range of metabolites of interest for industrial or medical use. The cultivation of freshwater Nostoc cf. linckia yielded 5.4 g/L of a crude exopolysaccharide (cEPS) with a molecular weight of 1.31 × 10 g/mol. Ion-exchange chromatography of cEPS yielded two dominant fractions, EPS-1 and EPS-2, differing in molecular weight. The lower molecular weight fraction (EPS-1) was subjected to structural studies. Results of chemical and spectroscopic analyses showed that three of the four dominant sugars, glucose, galactose and xylose are 1,4-linked in the backbone in the following order: [→4)-β-D-Xylp-(1 → 4)-β-D-Glcp-(1 → 4)-α-D-Galp-(1 → 4)-β-D-Glcp-(1→]. Terminal mannose residues were identified as side chains linked at C3 of every third backbone xylose and every second glucose is branched at C6 by 3-O-lactyl-β-D-glucuronic acid (nosturonic acid). Antioxidant properties of EPS were tested using two in vitro methods. Both assays showed that the cEPS was more active than purified EPS-1 and EPS-2 fractions and deproteinized EPS.
蓝藻产生广泛的代谢物，这些代谢物对工业或医学用途很有兴趣。淡水念珠藻 cf. 林克氏藻的培养产生了 5.4 g/L 的粗胞外多糖（cEPS），分子量为 1.31×10 g/mol。cEPS 的离子交换层析得到了两个主要的组分，EPS-1 和 EPS-2，分子量不同。分子量较低的组分（EPS-1）进行了结构研究。化学和光谱分析的结果表明，四种主要糖中的三种，葡萄糖、半乳糖和木糖在糖链骨架中以 1,4 键连接，顺序如下：[→4)-β-D-Xylp-(1→4)-β-D-Glcp-(1→4)-α-D-Galp-(1→4)-β-D-Glcp-(1→]。末端甘露糖残基被鉴定为侧链，连接在每个第三个骨架木糖的 C3 上，每个第二个葡萄糖在 C6 处被 3-O-乳酰基-β-D-葡萄糖醛酸（诺特糖醛酸）分支。使用两种体外方法测试了 EPS 的抗氧化性能。两种测定都表明，cEPS 比纯化的 EPS-1 和 EPS-2 部分以及去蛋白化的 EPS 更具活性。
