A comparative study of pectic polysaccharides from fresh and driedDendrobium officinalebased on their structural properties and hepatoprotection in alcoholic liver damaged mice

In this study, two pectic polysaccharides from fresh and dried Dendrobium officinale, namely FDP and DDP, were obtained by sour-water extraction, ethanol precipitation and further purification with DEAE cellulose-52 and Sephadex G-100 column chromatography. FDP/DDP had eight similar glycosidic linkages including 1,4-linked-GlcAp, 1,4- and 1,3,4-linked-GalAp, 1,3,4- and T-linked-Glcp, 1,6- and T-linked-Galp, T-linked-Galp and T-linked-Xylp. Besides, FDP was marked by 1,6-, 1,2,6-linked-Manp and 1,2,4-, 1,2-linked-Rhap, and DDP consisted of unique 1,6-linked-GlcAp and 1,3,6-Manp. FDP with a molecular weight of 14.8 kDa generally showed stronger scavenging capacity against DPPH, ABTS and hydroxyl radicals than DDP (p < 0.05). Pretreatment with FDP/DDP alleviated the alcohol-induced liver injury in mice, and their serum aminotransferase and triglyceride levels were 10.3%-57.8% lower than those of the model group (MG). Meanwhile, the FDP/DDP-M and FDP/DDP-H groups (200 and 300 mg kg-1) displayed a remarkable increase in antioxidant enzyme activities and significant reduction in inflammatory cytokine levels in comparison with the MG. Further analysis revealed that FDP-treated mice generally exhibited lower transaminase levels and inflammatory cytokine expression as well as higher antioxidant enzyme activities than DDP-treated ones. The FDP-H group showed significant restoration, which was slightly less than or almost comparable to that of the bifendate-fed positive control. The above results indicate that D. officinale pectin can attenuate oxidative stress and inflammatory cytokine response, and ultimately ameliorate liver injury, and "fresh" pectin with specific structural characteristics is expected to be more promising as hepatoprotective food.