Structural characteristics and hepatoprotective potential of Aralia elata root bark polysaccharides and their effects on SCFAs produced by intestinal flora metabolism

The structural characteristics of the polysaccharides from Aralia elata root barks (AERP) were systematically investigated by FT-IR, HPSEC-ELSD and colorimetric methods as well as by GCMS based monosaccharide compositions, Smith degradations, and methylation analysis. The result showed average molecular weights of AERP were between 42.7 kDa and 93.9 kDa. AERP was composed of Ara, Rha, GlcA, Man, Glc, and Gal in a molar ratio of 22.2: 10.3: 8.1: 32.7: 5.7: 21.2 along with a small number of sulfate (3.38%) and acetyl (4.87%) groups. The abundant glycosidic linkages of Man, Ara, Gal, and Rha were observed as more than 90% of all the monosaccharides detected. Studies to evaluate hepatoprotective potentials of AERP showed that they had potent hepatoprotective effects in vivo in carbon tetrachloride-induced acute liver injury (CIALI) in mice by histopathological evaluation, biochemical examinations and ELISA assays. GCMS was further used to determine the effects of AERP on the chemical profiles of nine common short-chain fatty acids (SCFAs) produced by intestinal flora metabolism in CIALI mice. These findings not only provide novel insights into the pharmacological actions of AERP on the protection from CIALI in mice, but they also demonstrate that determining SCFA profiles by targeted GC-MS metabolomics is an effective technique to investigate the molecular mechanisms of the effects of plant polysaccharides on intestinal flora metabolism.