Arabinogalactan

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Structural formula
Structure of arabinogalactan
General
Surname Arabinogalactan
other names
  • (+) - arabinogalactan
  • Galactoarabinan
  • Larch arabinogalactan
  • Arabinogalactan
  • Larch gum
  • Polyarabinogalactan
  • Larch arabinogalactan
CAS number 9036-66-2
Monomers / partial structures Galactose, arabinose
PubChem 24847856
Type of polymer

Biopolymer

Brief description

light brown, odorless solid

properties
Physical state

firmly

Melting point

> 200 ° C

solubility

very good in water about 50 g / l

safety instructions
GHS labeling of hazardous substances

(Arabinogalactan)

no GHS pictograms
H and P phrases H: no H-phrases
P: no P-phrases
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Arabinogalactan is a heteroglycan from plants and mycobacteria . It occurs in gum arabic and in gum ghatti , among others .

properties

Vegetable arabinogalactans

Arabinogalactan is a highly branched polysaccharide which consists of a galactan main chain with side chains of galactose and arabinose . It is a source of fiber and has been generally Recognized As Safe (GRAS) approved by the FDA since 1998 . It increases the number of Lactobacillus in the intestinal flora and lowers the ammonia concentration in the feces. Arabinogalactan decreases the number of monocytes and granulocytes in the spleen and increases the number of NK cells in the spleen in mice . Arabinogalactan from larch shows activation of the NK cells in relation to tumor cells in cell culture with increased levels of interferon -γ , tumor necrosis factor -α, interleukin -1β and interleukin-6, of which only IFN-γ activates the NK cells.

Arabinogalactans from Siberian larch can reduce the incidence of colds due to their immune-stimulating properties and increase the effectiveness of some vaccines .

Bacterial arabinogalactans

The microbial arabinogalactan is a major component of the mycobacterial cell wall , often bound to glycoproteins . Both galactose and arabinose occur here exclusively in furanose form . The galactan part is built up linearly from about 30 galactoses and is branched via β- (1-5) and β- (1-6) - glycosidic bonds . The arabinan chain consists of 30 arabinoses and is connected to the galactan chain at three points, presumably at arabinose 8, 10 and 12. The arabinose portion of arabinogalactan is a branched polysaccharide which is modified at the end with mycolic acids . The glycosidic bonds of the arabinan portion are α- (1-3), α- (1-5), and β- (1-2).

The reducing end of the mycobacterial arabinogalactan consists of the sequence (1 → 5) - D -Gal f - (1 → 4) - L -Rha p - (1 → 3) - D -GlcNAc. A muramyl-6-phosphate is found in the peptidoglycan . The mycolylated arabinogalactan is linked to the peptidoglycan by the Actinomycetaceae -typical linkage L -Rha p - (1 → 3) - D -GlcNAc- (1 → P). Arabinogalactan contains the galactan chain with alternating bonds (5-linked β- D -galactofuranosyl (Gal f ) and 6-linked β- D- Gal f ). The arabinan chains are linked to the C5 of the 6-linked β- D -Gal f . The Arabinan can be divided into three areas. The first area consists of linear 5-linked α- D -Ara f . The second area is branched with 3,5-connected α- D -Ara f , each of which has a 5-connected α- D -Ara f at both branches. The third area contains 3,5-linked α- D -Ara f , which have the disaccharide β- D -Ara f - (1 → 2) - α- D -Ara f at both branches (C8, C10 and C12).

The non-reducing end is linked to mycolic acids on the cell wall. The mycolic acids are connected via the 5-hydroxyls of the last two Ara f , mostly four mycolic acids on the penta-arabinosyl part (β-Ara f - (1 → 2) -α-Ara f ) 2 -3,5-α-Ara f , which corresponds to two-thirds coverage of the possible positions.

About one of the three arabinose linkages on the galactan chain contains up to three succinyl groups , usually one. Amino sugars are not succinylated. In Mycobacterium tuberculosis , the positively charged amino sugars and the negatively charged succinyls occur in the middle area of ​​the arabinan portion, more precisely at the O-2 of the inner 3,5-α- D -Ara f . The succinyls are on the chain without mycolic acid.

Individual evidence

  1. ↑ a b c d e f data sheet arabinogalactan from Sigma-Aldrich , accessed on November 22, 2012 ( PDF ).
  2. ↑ FDA: GRAS No. 017: arabinogalactan . Retrieved November 7, 2013.
  3. ↑ FDA: GRAS No. 084: Arabinogalactan from Eastern Larch ( Larix laricina ) . Retrieved November 7, 2013.
  4. ↑ RR Robinson, J. Feirtag, JL Slavin: Effects of dietary arabinogalactan on gastrointestinal and blood parameters in healthy human subjects. In: Journal of the American College of Nutrition. Volume 20, Number 4, August 2001, pp. 279-285, ISSN  0731-5724 . PMID 11506055 .
  5. ↑ NL Currier, D. Lejtenyi, SC Miller: Effect over time of in-vivo administration of the polysaccharide arabinogalactan on immune and hemopoietic cell lineages in murine spleen and bone marrow. In: Phytomedicine . Volume 10, Number 2-3, March 2003, pp. 145-153, ISSN  0944-7113 . doi: 10.1078 / 094471103321659852 . PMID 12725568 .
  6. ↑ J. Hauer, FA Anderer: Mechanism of stimulation of human natural killer cytotoxicity by arabinogalactan from Larix occidentalis. In: Cancer Immunology, Immunotherapy Volume 36, Number 4, 1993, pp. 237-244, ISSN  0340-7004 . PMID 8439987 .
  7. ↑ Riede L u. a .: Larch arabinogalactan effects on reducing incidence of upper respiratory infections. In: Current medical research and opinion. 2013 Mar; 29 (3): 251-8., PMID 23339578 .
  8. ↑ JK Udani, BB Singh, ML Barrett, VJ Singh: Proprietary arabinogalactan extract increases antibody response to the pneumonia vaccine: a randomized, double-blind, placebo-controlled, pilot study in healthy volunteers. In: Nutrition journal. Volume 9, 2010, p. 32, ISSN  1475-2891 . doi : 10.1186 / 1475-2891-9-32 . PMID 20796315 . PMC 2939641 (free full text).
  9. ↑ Ajit Varki (ed.): Essentials of glycobiology . 2nd Edition. Cold Spring Harbor Laboratory Press, New York 2009, ISBN 978-0-87969-770-9 , Chapter 20: Eubacteria and Archaea .
  10. ↑ a b c d e Bhamidi S: Mycobacterial Cell Wall Arabinogalactan . In: Bacterial Polysaccharides: Current Innovations and Future Trends . Caister Academic Press, 2009, ISBN 978-1-904455-45-5 .
  11. ↑ Suresh Bhamidi, Michael S. Scherman, Christopher D. Rithner, Jessica E. Prenni, Delphi Chatterjee, Kay-Hooi Khoo, Michael R. McNeil: The Identification and Location of Succinyl Residues and the Characterization of the Interior Arabinan Region Allow for a Model of the Complete Primary Structure of Mycobacterium tuberculosis Mycolyl Arabinogalactan . In: Journal of Biological Chemistry . tape 283 , no. 19 , 2008, p. 12992-13000 , doi : 10.1074 / jbc.M800222200 .
  12. ↑ Luke J. Alder Wick, Eva Radmacher, Mathias Seidel, Roland Gande, Paul G. Hitchen, Howard R. Morris, Anne Dell, Hermann Sahm, Lothar Eggeling, Gurdyal S. Besra: deletion of Cg-emb in Corynebacterianeae Leads to a Novel Truncated Cell Wall Arabinogalactan, whereas Inactivation of Cg-ubiA Results in an Arabinan-deficient Mutant with a Cell Wall Galactan Core . In: Journal of Biological Chemistry . tape 280 , no. 37 , 2005, pp. 32362-32371 , doi : 10.1074 / jbc.M506339200 .

literature

  • R. Kressmann: The chemical composition of the soluble colloids in the juice of black currants and their effect on the processing technology . Giessen 2003, DNB  968400361 , urn : nbn: de: hebis: 26-opus-11217 (dissertation).
  • PA Gleeson, AE Clarke: Antigenic determinants of a plant proteoglycan, the Gladiolus style arabinogalactan protein . In: Biochemical Journal . tape 191 , no. 2 , 1980, p. 437-447 , doi : 10.1042 / bj1910437 .