Structural characterization and anti-inflammatory activity of a pectin polysaccharide HBHP-3 from Houttuynia cordata

In this study, a hot buffer soluble Houttuynia cordata polysaccharide (HBHP-3) with a molecular weight of 397.4 kDa was isolated from H. cordata. HBHP-3 was composed of rhamnose, arabinose, glucose, galactose and galacturonic acid with molar ratio of 16.0:12.6:4.6:18.1:15.6. Structural analysis showed that the main chain of HBHP-3 was composed of →2)-α-L-Rhap-(1→, →4)-α-D-GalpA-(1→ and →4)-β-D-Galp-(1→. There were branched chains of α-L-Araf-(1→, →5)-α-L-Araf-(1→, →4)-α-D-Glcp-(1→, →6)-β-D-Galp-(1→, β-D-Galp-(1→ connected to the O-4 positions of →2)-α-L-Rhap-(1→. HBHP-3 effectively inhibited the secretion of NO and the mRNA expression of pro-inflammatory cytokines in a dose-dependent manner in macrophages. HBHP-3 inhibited the phosphorylation of p65 and IκBα proteins as well, illustrating that HBHP-3 exerted its anti-inflammatory activity by inhibiting the activation of NF-κB pathway.