Unveiling the structural characteristics and anti-inflammatory potential of a novel polysaccharide from sweet potato peels

Abstract

Sweet potato tubers generate a significant amount of peel waste during starch production, leading to resource inefficiency and environmental pollution. This research focused on the isolation/purification of a novel polysaccharide from sweet potato peel, named as sweet potato polysaccharide (SPP-W). The SPP-W has a molecular weight of 5.764 kDa and consist of glucose monosaccharides. The backbone of SPP-W was composed of →4)-α-D-Glcp-(1→, →4,6)-α-D-Glcp-(1→, and →3,4)-β-D-Glcp-(1→. The branched chain was α-D-Glcp-(1→ linked to the O-6 position of the sugar residue→4,6)-α-D-Glcp-(1→ and the O-3 position of the sugar residue→3,4)- β-D-Glcp-(1→ as confirmed by methylation and NMR analysis. SPP-W was found helpful in reducing the excessive NO, up-regulating IL-10, down-regulating the release of IL-6, IL-1β and TNF-α with LPS-induced RAW264.7 cell inflammation model. Furthermore, SPP-W effectively mitigates oxidative stress by reducing ROS levels, preventing nuclear damage, and preserving mitochondrial membrane potential in the context of inflammation. Immunoassays demonstrated that the clearance of endogenous ROS and the improvement of inflammatory conditions were attributable to the activation of the Nrf2 signaling pathway and inhibition of the NF-κB signaling pathway by SPP-W. Conclusively, SPP-W holds promise as a potential active ingredient for anti-inflammatory functional foods, offering unique and beneficial properties for further research and development.