Structural Characterization and Immunomodulatory Activity of a Polysaccharide From Ipomoea batatas L. Vine: Activation of Macrophage

ABSTRACT

Sweet potato vines, which have long been consumed in East Asia, are often underutilized despite being a nutritious functional food. In this study, a pectin named IBPS‐3A was isolated and purified from sweet potato vines. Comprehensive structural characterization using FT‐IR, monosaccharide composition analysis, methylation analysis, and 1D/2D NMR spectroscopy (COSY, HSQC, TOCSY, HMBC, and NOESY) identified IBPS‐3A as an acidic heteropolysaccharide with a molecular weight of approximately 56 kDa, primarily composed of a backbone containing →4)‐α‐D‐Gal p A‐(1 → and →2,4)‐α‐L‐Rha p ‐(1 → linkages with arabinogalactan side chains. Further investigation revealed that IBPS‐3A dose‐dependently induced M1 polarization in RAW264.7 macrophages, stimulating the secretion of TNF‐α, IL‐6, and NO and subsequently inhibiting co‐cultured B16 melanoma cell viability. Mechanistically, Toll‐like receptor (TLR) 4 and TLR2 represent potential receptors contributing to the immunostimulatory effects of IBPS‐3A leading to subsequent activation of the NF‐κB and MAPK (p38) signaling cascades. Collectively, these findings indicate that IBPS‐3A is a bioactive polysaccharide from sweet potato vines and highlight its potential for immunomodulatory applications.