Lipid-Lowering Mechanism of Lotus Root Polysaccharides in Drosophila Fed with a High-Fat Diet Based on Transcriptome Analysis

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.