Structure elucidation and antioxidant activity of a polysaccharide from Penthorum chinense Pursh

Penthorum chinense Pursh is a traditional Miao medicine, mainly used in the treatment of liver diseases. In this study, an acidic heteropolysaccharide PCPP was isolated from P. chinense with an average molecular weight of 14.96 kDa. PCPP contained arabinogalactan and homogalacturonan segments, which is formed by 4-Galp-(1 → 5)-Araf-1 and 3,6-Galp-(1 → 6)-Galp-1,3 glycosidic linkage. A variety of side chains, including t-Glcp-(1 → 4)-Glcp-(1 → 4)-GlcpA-1, t-Xylp-(1→, and 2-Manp-(1 → 4)-GalpA-1,3 linked to the O-3 and O-6 of 3,6-Galp. The antioxidant activity measurement in three models demonstrated that PCPP exhibited ROS scavenging capacity, antioxidant ability in the cellular model, enhancement of oxidative stress resistance, and healthspan-promoting effect in the worm model. These results provided the theoretical fundament of PCPP as a potential natural antioxidant.