Pretreatment of soybean hulls hemicellulose in ionic liquid facilitates anti-inflammatory oligosaccharides preparation

This study screened eight imidazole-based ionic liquids (ILs) for the pretreatment of soybean hulls to enhance the preparation of hemicellulose-derived oligosaccharides with anti-inflammatory activity. Results identified 1-butyl-3-methylimidazolium chloride ([Bmim]Cl) as the most effective solvent, universally improving hemicellulose yield by approximately two-fold and purity by 15% across alkali, acid, hydrothermal, organic solvent, and enzymatic extraction methods. Structural analyses revealed that [Bmim]Cl introduced significant surface voids and reduced crystallinity while effectively preserving the intrinsic chemical functional groups. Consequently, the modified hemicellulose exhibited significantly enhanced water-holding capacity, oil-holding capacity, and swelling ability. The derived oligosaccharides significantly downregulated the secretion of pro-inflammatory mediators, including NO, IL-6, and TNF-α, in LPS-induced RAW264.7 cells. The XOS4 fraction derived from Trichoderma xylanase displayed the most potent anti-inflammatory activity, resulting from a low polymerization average degree and a low arabinose/xylose ratio (0.64). In conclusion, the IL-mediated pretreatment strategy provides an efficient pathway for breaking down soybean hull recalcitrance.