0-Galactan

So far as we are aware, the galactan associated with pectin has hitherto been isolated in a reasonable degree of purity in one instance only, namely from the seeds of Lupinus albus. This source contains a comparatively high proportion of the galactan component + 35° in 

Only one other naturally occurring galactan has been examined in any great detail this is the e-galactan of the larch. It contains n-galacto- 

Although pectic materials are known to be present in wood, it is not clear whether this -galactan is a component of wood pectin, and in view of the wide difference in structure between this galactan and the one associated with pectin in lupin seeds, further investigations of this point will be awaited with special interest. 

G = D-Galactopyranose A = L-Arabofuranose residues linked to other residues through the numbered C-atoms 

—Repeating unit of e-GaJactan (possible formula) after E. V. White. 

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C (rapid heating). Manufactured by the oxidation of lactose or the galactans from wood with nitric acid. When heated with water it forms a soluble lactone. Converted to furoic... 

Pectin also contains araban and galactan. Il is present in fruits, root vegetables and other plant products, and confers on jams their typical gelling property. Pectin is manufactured as a white powder, soluble in water, and used to assist the setting of jams and jellies, and for numerous other purposes. Low melhoxyl pectins, with under 7% methoxyl, give firmer gels than pectins proper. 

Scientific name/Common name Glucan Xylan Galactan Arabinan Man nan Uronic anhydride Acetyl Lignin Ash... 

Note. Examples of established usage of the -an ending are xylan for polymers of xylose, mannan for polymers of mannose, and galactan for polymers of galactose. Cellulose and starch are both glucans, as they are composed of glucose residues. 

AG type II, known as arabino-3,6-galactan, has a (1 3)-y0-o-Galp backbone (Fig. 17) heavily substituted at position 6 by mono- and oligosaccha-... 

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]. 

Arabinofuranosides were removed from PVa, which resulted in an increase in the activity this was in contrast to the findings of Kiyohara et al. [35] who foimd no change in activity after removal of similar units from A. acutiloba pectin. For this polymer it was suggested that the minimum requirement for complement activation via the classical pathway was j6-l,6-linked galactan attached to the rhamnogalacturonan backbone, which also appears to be an important part of the backbone for PVa. 

The structure that appears to be important for the effect on the complement system is most probably the complex galactan ohgomer being composed of separate 1,3- and 1,6-hnked galactose chains with branch points being of 1,3,6 nature. These units have been proposed as the active sites for... 

Benzyl derivatives of (1 6)-a-D-glucan, (l->6)-a-D-mannan, and (l-> 6)-a-D-galactan have been studied in 1,4-dioxane. These derivatives have complex and interesting c.d. spectra due to the ww transition of the chromophore with resolved vibrational structure. However, a conformational interpretation of these interesting spectra is not possible at this time. 

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