Structural features and anti-inflammatory properties of pectic polysaccharides: A review

Pectic polysaccharides (PPs), consisting of four major structural domains, homogalacturonan (HG), rhamnogalacturonan-I (RG-I), rhamnogalacturonan-II (RG-II) and xylogalacturonan (XGA), possess significant anti-inflammatory function. Inflammation plays an essential role in the progression of many diseases. PPs are one of the new significant and non-toxic anti-inflammatory natural products that have been a hot research topic. However, the relationship between PPs and anti-inflammatory function is still unclear. Greater arduous efforts are urgently needed, thus, to evaluate the relationship between PPs and anti-inflammatory function. The aim of this contribution is to provide an overview of the recent advances in the anti-inflammatory bioactivity evaluation of PPs. Emphasis was made on the structure-function relationship between the four major PP domains and their associated inflammatory signaling pathways as well as the anti-inflammatory mechanism. PPs exert an anti-inflammatory effect via regulation of host immunity by directly targeting host immune cells or through activation of microbiota-nourishing immunity. The microbiota-nourishing immunity is related to enriched abundance of probiotic bacteria and improves host immune system function.