Structural characterization and anti-inflammatory activity analysis of novel polysaccharides extracted from sea...

Sea buckthorn (Hippophae rhamnoides) is a medicinal plant recognized for its therapeutic value. Although its polysaccharides are known to be bioactive, their precise structural characteristics and direct anti-inflammatory mechanisms remain largely undefined. This study isolated and purified two novel homogeneous polysaccharides, SBP50-0 and SBP70-0, from sea buckthorn aiming to elucidate their detailed structures and evaluate their anti-inflammatory activities in vitro.

SBP50-0 and SBP70-0 were identified as neutral polysaccharides with molecular weights of 1.04 × 10⁴ Da and 6.45 × 10³ Da, respectively. Monosaccharide analysis indicated they are composed of mannose, galactose, glucose, rhamnose and arabinose. Structural characterization via methylation and NMR spectroscopy revealed that both compounds possess unique, highly branched backbones, distinct from the linear chains often reported in literature. In lipopolysaccharide-stimulated RAW264.7 macrophages, treatment with SBP50-0 and SBP70-0 significantly inhibited nitric oxide production. Furthermore, they effectively suppressed the protein expression of key pro-inflammatory mediators, including interleukin-6, tumor necrosis factor-α and inducible nitric oxide synthase.

These findings demonstrate that SBP50-0 and SBP70-0 possess potent anti-inflammatory properties. This bioactivity is likely attributed to their specific structural architectures, particularly the highly branched arabinogalactan side chains and mannose-rich motifs that facilitate interaction with macrophage receptors. Consequently, these polysaccharides show significant promise as potential candidates for the development of natural anti-inflammatory functional foods or pharmaceutical agents. © 2026 Society of Chemical Industry.