A novel hemicellulosic polysaccharide (ACAP) was purified from the cold alkali extraction of alfalfa stems and characterized as a heteroxylan with a weight-average molecular weight of 7.94 × 10(3) kDa and a radius of 58 nm. Structural analysis indicated that ACAP consisted of a 1,4-linked β-D-Xylp backbone with 4-O-MeGlcpA and T-L-Araf substitutions at O-2 and O-3 positions, respectively. Transmission electron microscopy (TEM) examination revealed the entangled chain morphology of ACAP molecules. The evaluation of thermal degradation property revealed a primary decomposition temperature range of 238.8-314.0 °C with an apparent activation energy (Ea) and a pre-exponential factor (A) of 220.0 kJ/mol and 2.81 × 10(24)/s, respectively. ACAP also showed significant inhibitory activities on IL-1β, IL-6, and COX-2 gene expressions in cultured RAW 264.7 mouse macrophage cells. These results suggested the potential utilization of ACAP in functional foods and dietary supplement products.
Keywords: alfalfa polysaccharide; anti-inflammatory effect; hemicellulosic heteroxylan; structural analysis; thermal decomposition.