Structural elucidation and ameliorative effects of a pectic polysaccharide from Amomum longiligulare on ulcerative colitis

A new acidic polysaccharide was purified from Amomum longiligulare polysaccharides (ALP) and designated as ALP-D1 in this study. ALP-D1 has been characterized as a pectic polysaccharide, and its structure features a backbone composed of repetitive units of →4)-α- D -Gal p A-(1→4)-α- D -Gal p -(1→2)-α- L -Rha p - (1→4)-α- D -Gal p A-(1→2)-α- L -Rha p -(1→4)-α- D -Gal p A-(1→, accompanied by side chains of →3)-β- D -Gal p -(1→3)- D -Gal p -(1→. ALP has been shown to mitigate ulcerative colitis (UC) in mice through lowering disease activity index scores and reducing pathological damage in the colon. It resulted in decreased proinflammatory cytokine levels, including IL-1β, IL-6, and TNF-α, while elevating the concentration of the anti-inflammatory cytokine IL-10. Moreover, ALP enhanced the levels of tight junction proteins, including ZO-1, claudin-1, and occludin. Furthermore, ALP affected the composition of gut microbiota by modifying the ratio of Firmicutes, limiting harmful bacteria, and promoting the proliferation of Lactobacillus. The findings indicate that ALP positively influences UC by regulating inflammatory responses, strengthening the intestinal barrier, and adjusting gut microbiota, underscoring its possible role as an encouraging therapeutic choice for UC.