Our previous work has proved that lotus root polysaccharide has good lipid-lowering activity in vitro. In this work, we further investigated the lipid-lowering activity of lotus root polysaccharides in vivo and explored the underlying mechanism. The effects of two lotus root polysaccharides LRW (lotus root polysaccharide by water extraction) and LRA (lotus root polysaccharide by alkali extraction) on the food intake, lifespan, and lipid-lowering activity in Drosophila melanogaster induced by a high-fat diet were compared, and the lipid-lowering mechanism of lotus root polysaccharides was explored based on gene sequencing technology. The results showed that both LRW and LRA significantly prolonged the average lifespan of high-fat-diet-fed Drosophila, with more pronounced longevity-promoting effects observed for LRA. Medium- and high-dose interventions (5 and 10 mg/mL) of LRW and LRA enhanced intracellular antioxidant enzyme, superoxide dismutase (SOD), catalase (CAT) activities and markedly reduced malondialdehyde (MDA), total cholesterol (TC), and triglycerides (TG) levels under high-fat stress, demonstrating favorable in vivo lipid-lowering capacity, and LRA exhibited superior performance relative to LRW. Gene sequencing results suggested that several Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways including glycine, serine and threonine metabolism, alcoholic liver disease, peroxisome proliferator-activated receptor (PPAR) signaling pathway, galactose metabolism, etc., may be associated with the lipid-lowering effect of LRA, while LRW may be indirectly associated with lipid-lowering via phenylalanine and tyrosine metabolism pathways. This study provided a theoretical basis for lotus root polysaccharides in lipid-lowering application.

In this study, selenium nanoparticles (SeNPs) decorated with lotus root polysaccharide (LR) were successfully synthesized, and the formation, particle size, morphology and stabilization of LR/SeNPs1-5 with different Se content were comprehensively characterized. The findings revealed that LR/SeNPs exhibited uniformly spherical nanoparticles with particle size of approximately 100 nm. FT-IR and XPS spectra showed that the stability of LR/SeNPs was attributed to the formation of C-O⋯Se coordination bonds and hydrogen bond networks between LR and SeNPs. And the environmental stability experiment has proved that LR/SeNPs3 exhibit excellent stability in normal temperature, neutral and low-salt environments, howerer, to maintain long-term stability, it is necessary to avoid from high temperatures, high acidity and high salt environments. Also, the modification of the SeNPs with LR granted the LR/SeNPs excellent anti-inflammatory capability, that decreased the level of NO, IL-1β and TNF-α, and promoted macrophage toward the M2 phenotype polarization, during which LR showed a synergistic effect. These results suggest that LR can not only enhance the stability of SeNPs, but also improve the anti-inflammatory activity of SeNPs, thereby functioning as a promising stabilizing agent for SeNPs.