Structural elucidation of an immunological arabinan from the rhizomes of Ligusticum chuanxiong, a traditional Chinese medicine.

In the present study, an immunological arabinan, LCP70-2A, was isolated from Ligusticum chuanxiong for the first time. The absolute molecular weight of LCP70-2A was determined to be 6.46 × 104 g/mol using the HPSEC-MALLS-RID method. The absolute configuration of arabinose in LCP70-2A was determined to be L-configuration. Physicochemical characterization revealed that LCP70-2A was a homogeneous polysaccharide and had a backbone of (1 → 5)-linked α -L-Ara f with terminal α -L-arabinose residues at position O -2 and O -3. Molecular conformation analysis showed that LCP70-2A was a branching polysaccharide with a compact coil chain conformation in 0.1 M NaCl solution. In addition, in vitro cell assays showed that LCP70-2A can activate macrophages by enhancing the phagocytosis and potentiating the secretion of immunoregulatory factors including NO, TNF- α , IL-6, and IL-1 β. Furthermore, LCP70-2A was proved to promote the production of ROS and NO using the zebrafish model, suggesting that LCP70-2A can be further developed as a candidate supplement for immunological enhancement. Unlabelled Image • A novel polysaccharide (LCP70-2A) was isolated from the rhizome of L. chuanxiong. • LCP70-2A was determined to be an arabinan. • LCP70-2A increased the levels of NO, IL-6, IL-1 β , and TNF- α in RAW264.7 cells. • LCP70-2A was proven to enhance the immunoregulatory activity of zebrafish. [ABSTRACT FROM AUTHOR]