Rhamnogalacturonan II from the leaves of Panax ginseng C.A. Meyer as a macrophage Fc receptor expression-enhancing polysaccharide.
A complex pectic polysaccharide (GL-4IIb2) has been isolated from the leaves of Panax ginseng C.A. Meyer, and shown to be a macrophage Fc receptor expression-enhancing polysaccharide. The primary structure of GL-4IIb2 was elucidated by composition. 1H NMR, methylation, and oligosaccharide analyses. GL-4IIb2 consisted of 15 different monosaccharides which included rarely observed sugars, such as 2-O-methylfucose, 2-O-methylxylose, apiose, 3-C-carboxy-5-deoxy-L-xylose (aceric acid, AceA), 3-deoxy-D-manno-2-octulosonic acid (Kdo), and 3-deoxy-D-lyxo-2-heptulosaric acid (Dha). Methylation analysis indicated that GL-4IIb2 comprised 34 different glycosyl linkages, such as 3,4-linked Fuc, 3- and 2,3,4-linked Rha, and 2-linked GlcA, which are characteristic of rhamnogalacturonan II (RG-II). Sequential degradation using partial acid hydrolysis indicated that GL-4IIb2 contained alpha-Rhap-(1-->5)-Kdo and Araf-(1-->5) Dha structural elements, an AceA-containing oligosaccharide, and uronic acid-rich oligosaccharide chains in addition to an alpha-(1 -->4)-galacturono-oligosaccharide chain. FABMS and methylation analyses suggested that the AceA-containing oligosaccharide was a nonasaccharide in which terminal Rha was additionally attached to position 3 of 2-linked Arap of the octasaccharide chain observed in sycamore RG-II. Component sugar and methylation analyses assumed that the uronic acid-rich oligosaccharides possessed a similar structural feature as those in sycamore RG-II. GL-4IIb2 had a larger molecular mass (11,000) than sycamore RG-II (approximately 5000).
Shin
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KS
Oriental Medicine Research Center, Kitasato Institute, Tokyo, Japan.
Kiyohara
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Matsumoto
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Yamada
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D000818:Animals; D002240:Carbohydrate Sequence; D002478:Cells, Cultured; D008264:Macrophages / Q000187:drug effects* / Q000276:immunology; D008969:Molecular Sequence Data; D005894:Panax / Q000378:metabolism*; D010368:Pectins / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D010946:Plants, Medicinal; D011961:Receptors, Fc / Q000096:biosynthesis*
D011961:Receptors, Fc; C042492:rhamnogalacturonan II; D010368:Pectins