Glycobiology Advance Access originally published online on August 28, 2007
Glycobiology 2007 17(12):1299-1310; doi:10.1093/glycob/cwm088
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Immunological and Structural Properties of a Pectic Polymer from Glinus Oppositifolius
2 Department of Pharmaceutical Chemistry, School of Pharmacy, University of Oslo, P.O. Box 1068, Blindern, Oslo 0316, Norway
3 School of Biosciences, Sutton Bonington campus, University of Nottingham, Loughborough, Leicestershire LE12 5RD, UK
4 Laboratory of Biophysics and Surface Analysis, School of Pharmacy, University of Nottingham, University Park, Nottingham NG7 2 RD, UK
5 Department of Chemistry, Swedish University of Agricultural Sciences, P.O. Box 7015, Uppsala 750 07, Sweden
6 Kitasato Institute for Life Sciences, Kitasato University, 5-9-1 Shirokane Minato-ku, Tokyo 108-8641, Japan
7 Department of Traditional Medicine, B.P. 1746, Bamako, Mali
8 The Norwegian Institute of Public Health, P.O. Box 4404, Nydalen, Oslo 0403, Norway
9 Department of Anatomy, Institute of Basic Medical Sciences, University of Oslo, P.O. Box 1105, Blindern, Oslo 0317, Norway
1 To whom correspondence should be addressed: Tel: +47-2-28-56-572; Fax: +47-2-28-54-402; e-mail: k.t.inngjerdingen{at}farmasi.uio.no
Received on March 14, 2007; revised on August 13, 2007; accepted on August 13, 2007
The aim of this paper was to further elucidate the structure and the immunomodulating properties of the pectic polymer GOA2, previously isolated from Glinus oppositifolius. Enzymatic treatment of GOA2 by endo-
-D-(1
4)-polygalacturonase led to the isolation of three pectic subunits, GOA2-I, GOA2-II, and GOA2-III, in addition to oligogalacturonides. GOA2-I was shown to consist of 1,2-linked Rhap and 1,4-linked GalpA in an approximately 1:1 ratio, and NMR-analysis showed that the monomers were linked together in a strictly alternating manner. The galactose units in GOA2-I were found as terminal-, 1,3-, 1,6-, 1,4-, 1,3,4-, and 1,3,6-linked residues, while the arabinofuranosyl existed mainly as terminal- and 1,5-linked units. A rhamnogalacturonan-I type structure was suggested being the predominant part of GOA2-I. According to linkage analysis GOA2-II and GOA2-III contained glycosidic linkages characteristic for rhamnogalacturonan-II type structures. GOA2 was shown by sedimentation velocity in the analytical ultracentrifuge, to have a broad degree of polydispersity with a mode s20,w value of 
1.9 S, results reinforced by atomic force microscopy measurements. The polydispersity, as manifested by the proportion of material with s20,w > 3 S, decreased significantly with enzyme treatment. The abilities of GOA2, GOA2-I, GOA2-II, and GOA2-III to induce the proliferation of B cells, and to exhibit complement fixing activities were tested. In both test systems, GOA2-I showed significantly greater effects compared to its native pectin GOA2. GOA2-I was in addition shown to exhibit a more potent intestinal immune stimulating activity compared to GOA2. The ability of GOA2 to induce secretion of proinflammatory cytokines was examined. Marked upregulations in mRNA for IL-1ß from rat macrophages and IFN-
from NK cells were found.
Key words: Glinus oppositifolius / immunomodulation / pectic polymer / rhamnogalacturonan