Institute of Chemistry, Slovak Academy of Sciences, Dúbravská cesta 9, SK-84538, Bratislava, Slovakia.
Institute of Chemistry, Slovak Academy of Sciences, Dúbravská cesta 9, SK-84538, Bratislava, Slovakia.
Carbohydr Res. 2023 Dec;534:108946. doi: 10.1016/j.carres.2023.108946. Epub 2023 Sep 19.
Structure of biopolymers produced by microalgae plays an important role for their potential biological activity prediction and applications. Previously isolated and well characterized dominant fractions (Dch5-8) from ion-exchange chromatography separation of the biologically active microalga Dictyosphaerium chlorelloides exopolysaccharide (Dch) were pooled and partially acid hydrolyzed. The dominant sugar components in the combined Dch5-8 fraction were Gal and its 2-O-methyl derivative, Rha and Man, all accounting for about 94 mol% of total amount of sugars. Separation of obtained hydrolysate on Bio-Gel P-2 afforded ten fractions. Their main components were identified by NMR. Based on oligosaccharide structures, the repeating unit of the polysaccharide backbone was identified as →2)-α-L-Rhap-(1→4)-2-O-methyl-[3-O-β-D-Galp]-α-D-Galp-(1→ branched by Man. Furthermore, the higher molecular weight fraction contained glucuronorhamnan. NMR data indicate 1,4-linked Rha units in the backbone in α and β configuration, branched at O2 by 2,4-di-O-methyl-β-d-glucuronic acid.
微藻生物聚合物的结构对其潜在的生物活性预测和应用起着重要作用。先前从具有生物活性的微藻节旋藻多糖（Dch）的离子交换色谱分离中分离并充分表征的优势级分（Dch5-8）被合并并进行部分酸水解。在组合的 Dch5-8 级分中，主要的糖组分为 Gal 和其 2-O-甲基衍生物 Rha 和 Man，它们总共占总糖量的约 94 mol%。在 Bio-Gel P-2 上分离得到的水解产物分为十个级分。通过 NMR 鉴定了它们的主要成分。根据寡糖结构，多糖主链的重复单元被鉴定为→2）-α-L-Rhap-（1→4）-2-O-甲基-[3-O-β-D-Galp]-α-D-Galp-（1→，由 Man 分支。此外，高分子量级分含有葡醛酸岩藻聚糖。NMR 数据表明，主链中的 1,4-连接的 Rha 单元具有α和β构型，并在 O2 处由 2,4-二-O-甲基-β-d-葡萄糖醛酸分支。
