Extraction and Purification, Structural Characterization and Biological Activity of a Polysaccharide, PRP‐1, from Plumeria rubra

Abstract

AbstractPolysaccharides derived from the flowers of Plumeria rubra (PRP) have shown a variety of beneficial effects on improving human health. However, the structural features and bioactivities of PRP remain unclear. A novel neutral polysaccharide (named PRP‐1) with a molecular weight of 23 kDa was extracted and purified from the flowers of P. rubra. PRP‐1 was consisted of arabinose, galactose, glucose, xylose and mannose, with a molar ratio of 1.49: 27.89: 50.24: 13.02: 7.36. The structural characterization based on the methylation and 1D/2D nuclear magnetic resonance analyses indicated that PRP‐1 was composed of →4)‐Glcp‐(1→, →4,6)‐Glcp‐(1→, →4)‐Galp‐(1→, →2)‐Galp‐(1→, t‐Gal(p), →4)‐Manp‐(1→, →4,6)‐Manp‐(1→, t‐Man(p), →2)‐Xylp‐(1→, and t‐Xyl(p). Scanning electron microscopy revealed that PRP‐1 possess a compact three‐dimensional curling network structure in the terms of morphology. PRP‐1 exhibited anti‐inflammatory activity, which have moderate inhibitory effects on TNF‐α and IL‐6 production in lipopolysaccharide (LPS)‐induced RAW 264.7 cells. In addition, PRP‐1 showed ABTS, OH radicals scavenging and the Fe2+ chelating effects in a concentration dependent manner. In α‐glucosidase inhibition assay, PRP‐1 did not exhibit inhibitory activity. Overall, these results provide a scientific basis for the utilization of the flowers of P. rubra as a potential functional food ingredient.