Impact of esterification degree of pectic polysaccharides from quinoa microgreen on protective effects against dextran sulfate sodium-induced colitis in mice

Quinoa microgreen, as a nutrient-dense and health-promoting vegetable, contains abundant rhamnogalacturonan-I enriched pectic polysaccharides. However, their protective effects against ulcerative colitis (UC) and the influence of structural features like degree of esterification (DE) are poorly understood. Consequently, to overcome this gap in understanding, we systematically assessed the anti-UC activity of quinoa microgreen pectic polysaccharides (QMP) exhibiting distinct DE levels: QMP-HDE (28.49 %), QMP-MDE (16.8 %), and QMP-LDE (4.4 %). Results demonstrated that all these pectic polysaccharides significantly mitigated dextran sulfate sodium-induced UC through upregulating tight junction proteins, suppressing intestinal pro-inflammatory cytokines, promoting short-chain fatty acid production, and resorting gut microbiota homeostasis. Notably, low-DE QMP-LDE demonstrated superior efficacy to high-DE QMP-HDE in restoring intestinal barrier integrity (enhanced upregulation of tight junction proteins and reduced serum lipopolysaccharide) and in elevating anti-inflammatory cytokine interleukin-10. Although all pectic polysaccharides suppressed pathogenic genera ( Escherichia-Shigella, Klebsiella, and Helicobacter ), they differentially modulated beneficial bacteria ( Lactobacillus and Muribaculaceae). QMP-HDE selectively enhanced Lactobacillus abundance, whereas QMP-LDE specifically enriched Muribaculaceae. These differential effects among QMP-HDE and QMP-LDE are closely linked to their DE levels. Collectively, our findings shed light on the structure-anti-UC activity relationship of QMP pectic polysaccharides, supporting their potential application as functional foods to prevent intestinal inflammatory disorders.