Metabolism and Nutrition Department, Instituto de Ciencia y Tecnología de Alimentos y Nutrición (ICTAN), Consejo Superior de Investigaciones Científicas (CSIC), José Antonio Novais 10, Ciudad Universitaria, E28040, Madrid, Spain.
Talanta. 2012 May 15;93:153-9. doi: 10.1016/j.talanta.2012.01.067. Epub 2012 Feb 7.
Biological properties of polysaccharides from seaweeds are related to their composition and structure. Many factors such as the kind of sugar, type of linkage or sulfate content of algal biopolymers exert an influence in the relationship between structure and function. Besides, the molecular weight (MW) also plays an important role. Thus, a simple, reliable and fast HPSEC method with refractive index detection was developed and optimized for the MW estimation of soluble algal polysaccharides. Chromatogram shape and repeatability of retention time was considerably improved when sodium nitrate was used instead of ultrapure water as mobile phase. Pullulan and dextran standards of different MW were used for method calibration and validation. Also, main polysaccharide standards from brown (alginate, fucoidan, laminaran) and red seaweeds (kappa- and iota-carrageenan) were used for quantification and method precision and accuracy. Relative standard deviation (RSD) of repeatability for retention time, peak areas and inter-day precision was below 0.7%, 2.5% and 2.6%, respectively, which indicated good repeatability and precision. Recoveries (96.3-109.8%) also showed its fairly good accuracy. Regarding linearity, main polysaccharide standards from brown or red seaweeds showed a highly satisfactory correlation coefficient (r>0.999). Moreover, a good sensitivity was shown, with corresponding limits of detection and quantitation in mg/mL of 0.05-0.21 and 0.16-0.31, respectively. The method was applied to the MW estimation of standard algal polysaccharides, as well as to the soluble polysaccharide fractions from the brown seaweed Saccharina latissima and the red Mastocarpus stellatus, respectively. Although distribution of molecular weight was broad, the good repeatability for retention time provided a good precision in MW estimation of polysaccharides. Water- and alkali-soluble fractions from S. latissima ranged from very high (>2400 kDa) to low MW compounds (<6 kDa); this high heterogeneity could be attributable to the complex polysaccharide composition of brown algae. Regarding M. stellatus, sulfated galactans followed a descending order of MW (>1400 kDa to <10 kDa), related to the different solubility of carrageenans in red seaweeds. In summary, the method developed allows for the molecular weight analysis of seaweed polysaccharides with very good precision, accuracy, linearity and sensitivity within a short time.
海藻多糖的生物学特性与其组成和结构有关。许多因素，如糖的种类、连接方式或藻生物聚合物的硫酸根含量，都会影响结构与功能之间的关系。此外，分子量（MW）也起着重要作用。因此，开发并优化了一种简单、可靠且快速的高效凝胶渗透色谱（HPSEC）法，用于测定可溶性海藻多糖的 MW。当使用硝酸钠代替超纯水作为流动相时，色谱峰形状和保留时间的重复性得到了显著改善。使用不同 MW 的普鲁兰和葡聚糖标准品进行方法校准和验证。此外，还使用了主要的褐藻（海藻酸盐、褐藻糖胶、昆布多糖）和红藻（κ-和 ι-卡拉胶）多糖标准品进行定量和方法精密度及准确度分析。保留时间、峰面积和日间精密度的重复性相对标准偏差（RSD）分别低于 0.7%、2.5%和 2.6%，表明具有良好的重复性和精密度。回收率（96.3-109.8%）也表明其具有相当好的准确度。就线性而言，褐藻或红藻的主要多糖标准品具有非常高的相关系数（r＞0.999）。此外，该方法还具有较高的灵敏度，相应的检测限和定量限分别为 0.05-0.21 和 0.16-0.31mg/mL。该方法应用于标准海藻多糖 MW 的估计，以及褐藻裙带菜和红藻石花菜的可溶性多糖级分的 MW 估计。尽管分子量分布较宽，但保留时间的良好重复性为多糖 MW 的估计提供了良好的精密度。裙带菜的水和碱溶性级分的 MW 范围从非常高（＞2400 kDa）到低 MW 化合物（＜6 kDa）；这种高度异质性可能归因于褐藻复杂的多糖组成。对于石花菜，硫酸半乳糖聚糖的 MW 呈下降趋势（＞1400 kDa 至＜10 kDa），与红藻中卡拉胶的不同溶解度有关。总之，该方法可在短时间内对海藻多糖进行非常精确、准确、线性和灵敏的分子量分析。
