%0 Journal Article
%T Elucidation of the microstructure of an immuno-stimulatory polysaccharide purified from Korean red ginseng using sequential hydrolysis.
%A Lee SJ
%A In G
%A Lee JW
%A Shin KS
%J Int J Biol Macromol
%V 186
%N 0
%D Sep 2021 1
%M 34242646
%F 8.025
%R 10.1016/j.ijbiomac.2021.06.202
%X The elucidation of the structural characteristics of polysaccharides from natural sources is generally difficult owing to their structural complexity and heterogeneity. In our previous study, an immuno-stimulatory polysaccharide (RGP-AP-I) was isolated from Korean red ginseng (Panax ginseng C.A. Meyer). The present study aims to elucidate the structural characteristics of RGP-AP-I. Sequential enzyme hydrolysis was performed using four specific glycosylases, and chemical cleavage via β-elimination was carried out to determine the fine structure of RGP-AP-I. The degraded fragments were chemically identified using various chromatographic and spectrometric analyses, including HPLC-UVD, GC-MS, and tandem mass spectrometry. The results indicated that RGP-AP-I comprises a rhamnogalacturonan I (RG-I) backbone with repeating disaccharide units [→2)-Rhap-(1 → 4)-GalAp-(1→] and three side chains substituted at the C(O)4 position of the rhamnose residue in the backbone. The three side chains were identified as a highly branched α-(1 → 5)-arabinan, a branched β-(1 → 4)-galactan, and an arabino-β-3,6-galactan. Our results represent the first findings regarding the fine structure of the immuno-stimulatory polysaccharide RG-AP-I isolated from red ginseng.