Galactans polysaccharides

Galactans polysaccharides of o-galactose found in plants. They are usually unbranch and have high molecular masses. Examples are agar-agar and carrageenan. 

C15H26O13 414.363 D-Arabino-D-galactan polysaccharides have been isol. from cell walls of Mycobacterium sp a-(l ->5)-D-arabinofuran oligomers exist as the terminals of the polysaccharide chains. The terminal chains in the bacteria are responsible for the serological activity. 

A group of seaweed extracts, c. is constituted from sulfated galactan polysaccharides of different repeating units, such as D-galactose-sulfate and 3,6-anhydro-D-galactose-sulfate. 

The arabinogalactans have more frequently been reported for activity in various biological systems. Arabinogalactans are often classified in three groups arabino-4-galactans (Type 1), arabino-3,6-galactans (Type II) and polysaccharides with arabinogalactan side chains (Type III) [14]. The latter type are also called the real pectins [10,11]. Only types I and II will be dealt with in this chapter, as Type III are equal to the pectins discussed below. 

Ginsenan S-IIA, a polysaccharide fraction from the roots of P. ginseng is a potent inducer of IL-8 production by human monocytes and THP-1 cells, and this induction is accompanied by increased IL-8 mRNA expression. The polysaccharide appears from the structural feature to be a mixture of arabino-galactan type I and type II, based on the presence of 1,3-, 1,6-, 1,3,6-, 1,4-, and 1,4,6-galactose units as well as terminal arabinose and 1,5-, 1,3,5-, and 1,2,5-linked units. It also contains 1,4,6-linked glucose units that together with the 1,2,5-linked arabinose units are different from the units found in other ginseng polysaccharides and may thus be of importance for the activity [64]. 

Echinacea-polysaccharide II consists of arabino-3,6-P-galactan part, rhamnogalacturonan part and arabinan part [5], therefore it is suggested that the polysaccharide may be certain ramified region of pectic polysaccharide. 

The glycoproteins and water-soluble polysaccharides contain mainly galactan with some araban.95... 

Alternatively, if we suppose that the hexose polysaccharide is produced first and is then transformed into pectic acid and araban, at least two types of galactan, other than the one already isolated from pectic materials, would be required to account for the types of structure present respectively in pectic acid and araban. This would seem to be somewhat unlikely since, on this view, one would expect to encounter other types of pectic acid and araban, whereas on the evidence now available the pectic acid isolated from all samples of pectic materials examined appears to be the same, and a similar conclusion applies in the case of the araban. 

ESI-MS/MS analysis. Also Becker et al. employed a combination of NMR with chemical analysis and additional biophysical techniques to deduce the structure of 2-sulfated, 3-linked ot-L-galactan and a-L-fucans.46 It was indicated that the extremely different conformations of the two polysaccharides could help to explain their distinct anticoagulant properties. 

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