Molecular structures, chemical properties and biological activities of polysaccharide from Smilax glabra rhizome

The water-soluble crude polysaccharides, extracted from the rhizome of Smilax glabra, were fractionated using an anion exchange chromatography, yielding two fractions, F₁ and F₂. The crude and fractions (F₁ and F₂) mainly consisted of carbohydrates (66.7%-91.1%), proteins (7.30%-23.9%) and minor amount of sulfates (1.60%-9.40%). Glucose was the major monosaccharide unit of the polysaccharides with different levels of sugar constituents including galactose, arabinose, rhamnose and mannose. The molecular weight (M_w) of crude and fractions ranged from 32,102-6.3 × 10³ g/mol. The crude and fractions could stimulate RAW264.7 cells to release nitric oxide and cytokines via up-regulation of their mRNA expression by the activation of NF-κB and MAPKs pathways. The related pattern recognition receptors (PRRs) on the surface of the cells appeared to be TLR2 and CR3. The GC-MS analysis revealed that the main backbone of the most immune-enhancing F₂ was (1 → 4)-linked glucose and galactose chain with minor linkages of (1 → 6)-galactose, (1 → 3)-mannose, (1 → 2)-rhamnose and (1 → 5)-arabinose with some branches at C-3 and C-4 rhamnose, or C-6 galactose.