Structural Characterization and Transcript-Metabolite Analysis of Macrophage Immunomodulation Induced by Luffa aegyptiaca Polysaccharide

Luffa aegyptiaca exhibits broad medicinal and therapeutic potential, with its polysaccharide component identified as a key contributor to its biological activities. However, the specific molecular structures and immunomodulatory mechanisms of these polysaccharides remain largely unclear, which hinders their further development for medicinal development. In this study, a novel polysaccharide, named LAP-C1, was extracted and purified from L. aegyptiaca using a DEAE-52 cellulose column. Its molecular characteristics and immunomodulation mechanism were systematically investigated using various analytical techniques, combined with integrated transcriptomic and metabolomic analyses. LAP-C1 contained 56.17% total carbohydrates and 38.33% uronic acids. Monosaccharide composition analysis revealed that LAP-C1 primarily consists of fucose (3.74%), arabinose (11.71%), rhamnose (16.16%), galactose (37.60%), glucose (4.76%), galacturonic acid (23.44%), and glucuronic acid (2.57%). The immunomodulatory assay demonstrated that LAP-C1 enhanced the phagocytic ability of RAW264.7 macrophages, the nitric oxide (NO) production, and cytokine secretion (IL-6, IL-1β, and TNF-α). Transcriptomic and metabolomic analyses revealed that LAP-C1 exerts its immunomodulatory effects primarily by activating the alpha-linolenic acid and arachidonic acid metabolism pathways. This study provides critical insights into the molecular structure and immunostimulatory mechanisms of Luffa-derived polysaccharides, thereby laying a foundation for their potential application in immunomodulatory therapies and biomedical development.