Structural Characterization and Anti-inflammatory Activities of Anticomplementary Polysaccharides from Rhododendron principis

Rhododendron principis leaves have been used as Dama, a Traditional Tibetan Medicine for treating inflammatory diseases. R. principis crude polysaccharides with anticomplementary activity demonstrated promising anti-inflammatory effects on acute lung injury induced by lipopolysaccharide. R. principis crude polysaccharides significantly decreased the levels of TNF-alpha and interleukin-6 in both serum and blood and bronchoalveolar lavage fluid in lipopolysaccharide-induced acute lung injury mice by intragastric administration (100mg/kg). A heteropolysaccharide, ZNDHP, was obtained from R. principis crude polysaccharides with successive anti-complementary activity-guided separation. ZNDHP was characterized as a branched neutral polysaccharide with a backbone composed of -> 2)-beta-Glcp-(1 ->, -> 2,6)-alpha-Glcp-(1 ->, -> 6,3)-beta-Galp-(1 ->, -> 2,6)-alpha-Galp-(1 ->, -> 6,2)-beta-Glcp-(1 ->, -> 4)-alpha-Glcp-(1 ->, -> 5)-beta-Araf-(1 ->, -> 3,5)-alpha-Araf-(->, and -> 4,6)- beta-Manp-(1 ->, and the backbone structure was further confirmed by partial acid hydrolysis. In addition to anticomplementary and antioxidant activities, ZNDHP exhibited potent anti- inflammatory activity by significantly inhibiting the secretion of nitric oxide, TNF-alpha, interleukin-6, and interleukin-1 beta of lipopolysaccharide-treated RAW 264.7 cells. However, all of these activities decreased greatly after partially hydrolyzing, indicating the importance of the multibranched structure for its bioactivity. Therefore, ZNDHP might be an important component of R. principis for treating inflammation.

Automated summary

Rhododendron principis leaves have been used as a Traditional Tibetan Medicine for treating inflammatory diseases. A polysaccharide named ZNDHP was obtained from the leaves and showed promising anti-inflammatory effects by inhibiting the secretion of inflammatory cytokines. The multibranched structure of ZNDHP is crucial for its bioactivity.