Structural characterization and anti-inflammatory activities of a purified polysaccharide from fruits remnants of Alpinia zerumbet (Pers.) Burtt. et Smith

We reported here an interesting source of Alpinia zerumbet Polysaccharides (named AZPs) from the residues after extracting essential oil by steam distillation from Alpinia zerumbet fructus. After a series of purifications, a homogeneous polysaccharide (AZP-2) of molecular weight 1.25 × 10 5  Da was obtained. Structure, anti-inflammatory activity, and anti-inflammatory mechanism were investigated. AZP-2 was mainly composed of galactose, arabinose, xylopyranose, glucose, and galacturonic acid. The main linkage structure of AZP-2 was determined after integrating the nuclear magnetic resonance (NMR) and methylation analysis, and the structure was comparatively complex. The results indicated that AZP-2 significantly decreased the production of NO and ROS in the inflammatory model established by lipopolysaccharide (LPS) stimulated RAW264.7, particularly at the concentration of 200 μg/mL. Furthermore, AZP-2 significantly modulated the secretion of both pro-inflammatory and anti-inflammatory cytokines. Notably, the mechanism of AZP-2 exhibiting inhibitory effects was related to regulating the NF-κB signaling pathway. Overall, AZP-2 could be used as a potential anti-inflammatory agent for further in-depth studies.