Structural characterization and in vitro hepatoprotective activity of an acidic polysaccharide from Dendrobium nobile Lindl. flower.

This study aimed to investigate the structural characterization, conformational properties, and hepatoprotectiveactivity of acidic polysaccharide (DNLPS-3) from Dendrobium nobile flower. DNLPS-3 with molecular weights of 15.65 KDa was composed of Fuc: Rha: Ara: Gal: Glc: Xyl: GalA: GlcA in a molar ratio of 0.26%: 2.38%: 4.47%: 3.55%: 0.43%: 17.84%: 69.80%: 1.26%. Structural analysis with methylation indicated that DNLPS-3 mainly contained T-Ara(f), T-Xyl(p), T-Gal(p)A, 3-Gal(p)A, 4-Gal(p)A, 3,4-Gal(p)A, 3,4-Glc(p), 2,4-Gal(p)A, 2,3,4-Gal(p), 4,6-Gal(p), 3,4,6-Gal(p). NMR results show that DNLPS-3 may be a pectin polysaccharide with →4)-α-Gal(p)A-(→main chain. In vitro experiments showed that DNLPS-3 exhibited significant hepatoprotective effects. The effect was achieved by reducing the activities of ALT and AST, suppressing the production of LDH and MDA, and enhancing the anti-oxidant activities of SOD and GSH, and the specific mechanism of its hepatoprotective effect is that DNLPS-3 up-regulates Nrf2/HO-1 pathway protein expression.