Mucilages polysaccharides from

Polysaccharides based on D-mannose as the major structural unit occur in woods and in the seeds of many plants. Although polysaccharides from the latter sources are often classified as seed mucilages, this term is unsatisfactory and, in view of close similarities in structure, the two groups of polysaccharides may be considered together. 

Many polysaccharides contain L-rhamnose as a constituent, and various methylated L-rhamnoses have therefore been isolated by the hydrolysis of methylated gums and mucilages. For example, trimethyl-L-rhamnopyranose has been isolated from methylated gum arabic86 and from the methylated polysaccharide from the somatic portion of the cells of Mycobacterium tuberculosis,26 and in both these polysaccharides L-rham-nopyranose residues evidently occupy terminal positions in the molecule. 

CAS 9000-30-0. A water-soluble plant mucilage obtained from the ground endosperms of Cyanopsis tetragonoloba, cultivated in India and Pakistan as livestock feed, as well as in southwestern U.S. The water-soluble portion of the flour (85%) is called guaran and consists of 35% galactose, 63% mannose, probably combined in a polysaccharide, and 5-7% protein. 

Table 8. Monosaccharide composition (%) and content of polyanionic sulfate in extracellular polysaccharides and a mucilage sample from the Adriatic... 

Tomoda M, Shimizu N, Shimada K, Gonda R, Sakabe H (1984) Plant mucilages XXXIV. The location of O-acetyl groups and the structural features of plantago-mucilage A, the mucous polysaccharide from the seeds of Plantago asiatica. Chem Pharm Bull 32 2182-2186... 

It is sometimes claimed that mucilage and similar gels may help to maintain hydraulic conductivity between root and. soil (52). However, the hydraulic conductivity of soils is often substantially decreased when soils are irrigated with waste water. Apart from the inducement of sodicity, which is real in many cases, the decreases in hydraulic conductivity are attributed largely to the production of microbial biomass, particularly extracellular polysaccharides (e.g.. Ref. 53). These extracellular polysaccharides form gels that may store large quantities of water and allow water and ions to diffu.se through them at rates not much less than those of free water, but they could be expected to restrict mass flow of water and thus nutrients, to roots (54). 

An attempt has been made to classify gums into two main groups (a) real gums which are those plant products which form a clear solution in water and (b) vegetable mucilages which are those which swell but do not dissolve completely in water. This classification is useful but not entirely satisfactory since there are exceptions. Thus gum traga-canth, a tree exudate and a true plant gum, is only partially soluble in water and exhibits those properties normally attributed to mucilages. In this section of the article the term plant gum will be restricted to those complex acid polysaccharides which are exuded from trees either spontaneously or after mechanical injury. 

Closely related to plant gums are those mucilages discussed later which are the complex acid polysaccharides extractable from endosperms of seeds of such plants as flax, quince and lucerne (see below). The acid nature of these mucilages is due to the presence of D-galacturonic acid residues in the complex molecule. ... 

In this clas of materials is grouped the majority of the seed mucilages, the acidity of which is due to a uronic acid (usually D-galacturonic acid) or to a methyl ether derivative of a uronic acid. This presence of D-galacturonic acid as the acidic component of the polysaccharide differentiates the mucilages from the gums, the acidity of the majority of which is due to the presence of D-glucuronic acid, or to one of its methyl ether derivatives (see above). 

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