[Isolation, purification and immunomodulatory activity of polysaccharide from Lonicera caerulea L. var. edulis Turcz. ex Herder].

Abstract

Objectives: To isolate a novel polysaccharide (THP-2) from Lonicera caerulea L.var. edulis Turcz. ex Herder (L. caerulea) and evaluate its immunomodulatory activity.

Methods: Ultrasonic-assisted water extraction and alcohol precipitation and gel column chromatography were used to separate and purify polysaccharides from L.caerulea. The relative molecular mass, purity and chemical structure of THP-2 were analyzed by gel permeation chromatography, ion chromatography, periodate oxidation and smith degradation, infrared spectroscopy, nuclear magnetic resonance spectroscopy and Congo red experiment. DC2.4 cells and Raw264.7 cells were used to evaluate the immunomodulatory activity of THP-2.

Results: A new polysaccharide component THP-2 was isolated and purified from L.caerulea, and its chemical composition and structural characteristics were significantly different from those of L.caerulea polysaccharide reported previously. The average relative molecular mass of THP-2 was 123 090, and its monosaccharide components included sugar, galactose, glucose, mannose, xylose, glucuronic acid and galacturonic acid with a molar ratio of 27.84:52.28:8.47:6.05:2.75:0.90:0.88:0.83. Glycosidic bond analysis showed that THP-2 was mainly composed of (1→5), (1→3), (1→4), (1→6), (1→3,4), (1→6,4) and other glycosidic bonds. THP-2 could activate expressions of costimulatory molecules CD80, CD86, CD40 and MHC-II and promote IL-1β, IL-6 and TNF-α secretion in DC2.4 cells, up-regulate CD80, CD86 and CD40 expressions and enhance the expressions of IL-1β, IL-6 and TNF-α in Raw264.7 cells. THP-2 also promoted iNOS expression, increased NO secretion, and up-regulated p-p65 and p-IκB expressions in both cells, and increased p-Akt protein content in DC2.4 cells.

Conclusions: The new polysaccharide component THP-2 isolated from L.caerulea is capable of promoting maturation and differentiation of DC2.4 cells by activating the NF‑κB signaling pathway and PI3K/Akt pathway and promoting the differentiation of Raw264.7 cells into M1 macrophages through the NF-κB pathway.