<i>In vitro</i> and <i>in vivo</i> effects of pectin-type polysaccharides isolated from crabapples ( <i>Malus prunifolia</i> ) on inflammatory colitis models

Abstract The aim of this study was to investigate the anti-inflammatory effects of polysaccharides extracted from crabapples (Malus prunifolia; MP) in vitro and in vivo. Crabapples were subjected to hot water extraction to obtain MP-HW, which was further separated into low (MP-L) and high molecular weight (MW) (crude polysaccharide; MP-CP) fractions by ethanol precipitation. Based on MW distribution, general composition, component sugars, and Fourier transform infrared spectroscopy, MP-CP was identified as a pectin-type polysaccharide rich in galacturonic acid with an MW of 106.2 kDa. MP-CP inhibited the production and mRNA expression of proinflammatory factors in an IL-1β-treated intestinal epithelial cell model. In addition, MP-CP significantly alleviated the body weight, disease activity index score, colon length, and spleen weight in mice with dextran sulfate sodium (DSS)-induced colitis. The MP-CP-treated group showed effective regulation of the expression of pro- and anti-inflammatory factors and immunoglobulin A than the DSS-treated group. Haematoxylin and eosin and Alcian blue staining revealed that MP-CP alleviated inflammatory manifestations and mucin expression in the intestinal lumen. Collectively, pectin-type polysaccharides isolated from crabapples may be used as a new functional food and pharmaceutical agent for the prevention and treatment of inflammatory colitis.