Structural properties of two glycans in the fruits of jujube and their regulation effect of M1-type and M2-type macrophage

Two glycans, ZJPr2–2-1 and ZJPr3–2-1 , were isolated from jujube fruits. Structural analysis revealed ZJPr2–2-1 (7.20 kDa) as a previously unreported pectin featuring main chain of →4)- α -D-Gal p A-(1→, →3,4)- α -D-Gal p A-(1→, and →3)- α -L-Rha p -(1→, with side chains containing →4)- α -L-Ara p -(1→, and t-4-deoxy-L- threo -hex-4-enopyranuronic acid (t- α -L-HexA), as well as two isolated fragments linked to →4)- β -D-Gal p A, →4)- α -D-Gal p A. Nevertheless, the absence of HMBC correlations precluded the structural elucidation of its connected side chain. Meanwhile, ZJPr3–2-1 was identified as the first plant-derived cyclic α -1,6-glucan heptasaccharide. Both glycans were found to promote M1 macrophage polarization (increased CD86 and decreased CD206 expression), and enhance the production of pro-inflammatory mediators (NO, iNOS, and TNF- α ) in RAW264.7 cells. The mechanism was supposed to associated with the direct ( ZJPr3–2-1 ) and indirect ( ZJPr2–2-1 ) activation of the Dectin-1/Syk signaling pathway.