Abstract
Lotus root is a widely popular aquatic vegetable with edible and medicinal values. Here we report the structure and lipid-lowering activity of two lotus root polysaccharides LRW (lotus root polysaccharide by water extraction) and LRA (lotus root polysaccharide by alkali extraction), that were extracted by aqueous and alkaline solution respectively. The results showed that the yield of polysaccharide from lotus root could be significantly improved by alkali extraction. Basic composition and structural characterization showed that the total sugar contents of LRW and LRA were 96.83 % and 73.66 %, and the molecular weights were 2.464 × 105 Da and 1.727 × 105 Da, respectively. LRW and LRA had the similar structure that the main backbone consisted of →4)-α-D-Glcp-(1→ with branches at C-6 site. Both LRW and LRA could scavenge DPPH and hydroxyl radicals effectively, and have strong adsorption capacity to cholate salts in a concentration-dependent manner. In HepG2 cells, LRW and LRA inhibited the accumulation of lipid droplets induced by oleic acid, and increased the activity of T-SOD and CAT, meanwhile, reduced the level of MDA, TC and TG, showing good lipid-lowering activity. In comparison, the lipid-lowering effect of LRA was better than that of LRW. In addition, gene sequencing and RT-PCR showed that AMPK, ACC, PPARα and CPT-1 were essential for LRA to exert a lipid-lowering effect. This study provides a theoretical basis for the extraction and lipid-lowering application of lotus root polysaccharides.
藕是一种广泛流行的具有食用和药用价值的水生蔬菜。我们易阳教授、孙莹老师等人分别用水提法和碱提法提取的两种藕多糖LRW和LRA，并对其结构和降脂活性进行了系统研究。结果表明，碱提法可显著提高莲藕多糖的得率。基本组成和结构表征表明，LRW和LRA的总糖含量分别为96.83 %和73.66 %，分子量分别为2.464 × 105 Da和1.727 × 105 Da。LRW和LRA具有相似的结构，主要由 → 4)-α-D-glcp-(1 → 组成，在C-6位点有分支。LRW和LRA均能有效清除DPPH和羟基自由基，对胆酸盐具有较强的吸附能力，且呈浓度依赖性。在HepG2细胞中，LRW和LRA抑制油酸诱导的脂滴积聚，提高T-SOD和CAT活性，同时降低MDA、TC和TG水平，表现出良好的降脂活性。相比之下，LRA的降脂效果优于LRW。此外，基因测序和RT-PCR结果显示，AMPK、ACC、PPARα和CPT-1是LRA发挥降脂作用所必需的。本研究为莲藕多糖的提取及降脂应用提供了理论依据。
研究成果于近日发表于国际学术期刊Food Research International。食品学院研究生宋洁、张召为论文共同第一作者，易阳教授、孙莹老师为共同通讯作者。该研究得到湖北省重点研发计划项目（2022BBA0023）资助。
文章链接：https://doi.org/10.1016/j.foodres.2025.115801
