Plant gums containing uronic acids

Most of the known oligoglycuronic acids are aldobiouronic acids. Because of the stability of the glycosidic linkage of aldobiouronic acids toward acid hydrolysis, they are readily isolated after vigorous hydrolysis of polysaccharides that contain uronic acid residues. They have been obtained from wood hemicelluloses, plant mucilages, gums, bacterial and animal polysaccharides, and by synthesis. 

Compounds known to behave in this way in vivo are listed in recent reviews in this Series.1 2 The structures of some of the /3-D-glucopyranosiduronic acids isolated from urine have been proved by chemical synthesis.3 A few similar derivatives of flavones and triterpenes have been isolated from plants. D-Glucuronic acid also occurs in mammalian tissues as a constituent of acid mucopolysaccharides (aminodeoxypolysaccharides, containing uronic acid), such as hyaluronic acid, chondroitinsulfate, and heparin,4 and it is a direct precursor of L-ascorbic acid in plants and mammals.6 It is present in many of the plant polysaccharides classified as hemicelluloses6 and gums,7 and it has also been found in certain bacterial polysaccharides.4... 

Polyuronides may be defined as polysaccharides that contain one or more uronic acid units in their molecular structures. They have a frequent and wide occurrence in nature. Much of the carbohydrate material in plants belongs to the group. It includes all pectic materials and plant gums and many plant mucilages, hemicelluloses and gel-forming substances and some microbial polysaccharides. These substances are to be looked for in water-soluble plant exudates and mucilages, as well as in water and alkaline extracts of most plant materials. This review will be limited to the polyuronides occurring in plants. 

Chem. Soc. 1953, 2332. Structure is a partially acetylated polysaccharide containing about 8% acetyl groups and about 37% uronic acid residues. Reviews F. Smith, R. Montgomery, The Chemistry of Plant Gums and Mucilages (Reinhold, New York, 1959)1 Goldstein, Alter, in Industrial Gums. R. L. Whistler, Ed. (Academic Press, New York, 2nd ed., 1973) pp 273-287. 

Plant gums and mucilages are high molecular weight polysaccharides composed of hexoses and pentoses. They also contain some uronic acid units. Among the gums are gum arabic, gum tragacanth, and many others. 

Many plant gums and mucilages have been found to contain a mixture of uronic acids and pentoses. Early analyses of these substances suggested that homologous mixtures of hexose, hexuronic acid, and pentose, such as D-galactose, D-galacturonic acid, and L-arabinose, or of uronic acid and... 

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