The structural features and anti-inflammatory properties of a glucogalactan from Holotrichia diomphalia Bates (Qi Cao)

Abstract

Ethnopharmacological relevanceThe dried larvae of Holotrichia diomphalia Bates, named Qi Cao, is a traditional Chinese medicine treat for liver diseases and arthritis. Polysaccharides is a principal component in Qi Cao, which exhibiting antioxidant and anti-inflammatory effects. However, the structural characteristics and underlying mechanisms of the polysaccharides remain inadequately elucidated. Aim of the studyTo analyze the primary structure and elucidate the molecular anti-inflammatory mechanisms of the active polysaccharide in Qi Cao. Materials and methodsThe total polysaccharide was extracted by water extraction and alcohol precipitation, and further isolated and purified by DEAE Sephadex A-25 column and Sephadex G-100 column. The anti-inflammatory properties of four major fractions (HDPS-1, HDPS-2, HDPS-3, HDPS-4) and the pure homogeneous polysaccharides (HDPS-1I and HDPS-1II) were assessed using a RAW 264.7 cell model induced by lipopolysaccharide (LPS), and HDPS-1II was identified as the polysaccharide exhibiting significant anti-inflammatory activity in Qi Cao. The structural characteristics of HDPS-1II were subsequently analyzed using high-performance size-exclusion chromatography (HPSEC), fourier-transform infrared spectroscopy (FT-IR), gas chromatography-mass spectrometry (GC-MS), and nuclear magnetic resonance (NMR) spectroscopy. The TLR4, NF-κB, COX-2 and iNOS expressions were determined by Western blot analysis to investigate the anti-inflammatory mechanism of HDPS-1II in vitro. Finally, the in vivo anti-inflammatory activity of HDPS-1II were evaluated by measuring the serum levels of pro-inflammatory factors, inflammatory cell infiltration and organelle damage in the lung tissues of sepsis model mice. ResultsA homogeneous polysaccharide (HDPS-1II) with molecular weight of 1.7 × 104 Da was isolated from Holotrichia diomphalia Bates. HDPS-1II contains a backbone of α-T-Glcp-(1 → 6)-α-Glcp-(1 → 4)-α-Galp-(1 → 4)-α-Galp-(1 → 6)-α-Galp-(1 → 3)-α-Galp-(1 → . It inhibited activation of the TLR4/NF-κB signaling and reduced pro-inflammatory factors and NO in LPS-stimulated macrophage. Moreover, HDPS-1II increased the survival rate, inhibited inflammatory cells infiltration, and ameliorated the lung tissue damage in septic mice. ConclusionsHDPS-1II exhibits anti-inflammatory effects in vitro and in vivo, which is the active polysaccharide components of the anti-inflammatory activity of Qi Cao.