Glucuronic acid, methyl derivatives

Pryde and Williams41 first synthesized a derivative of 2,5-di-O-methyl-D-glucuronic acid. Methylation of D-glucuronolactone with... 

A series of derivatives analogous to those from D-glucuronic acid has been made by Morell and Link.68 An important compound is the crystalline methyl ester of methyl a-D-galacturonoside (XXXII) which on alkaline hydrolysis yields methyl a-D-galacturonoside (XXXIII). Since... 

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). 

Approximately 50% of a dose of mestranol is de-methylated to form ethinyl estradiol. Ethinyl estradiol also can be deethinylated. Subsequently, the metabolism of these two synthetic estrogens proceeds by means of the same pathways as the natural steroid hormones. The principal metabolites of mestranol and ethinyl estradiol are hydroxylated derivatives that are conjugated with either glucuronic acid or sulfate. The synthetic steroid estrogens, in contrast to the natural estrogens, are excreted primarily in the feces. 

In concentrated sulfuric acid, D-glucuronic acid is dehydrated more slowly than either its 4-O-methyl derivative or D-glucose, probably because of the stability of its lactone. All hexuronic acids, however, eventually produce the same characteristic absorbance that corresponds roughly to a composite of 5-formyl-2-furoic acid, 2-furaldehyde, and reductic acid. It is interesting that a thin-layer chromatographic examination of the reaction products of D-glucuronic acid with 89% sulfuric acid at 70° revealed 5-formyl-2-furoic acid as a major product, but no evidence was obtained for the presence of reductic acid. This result is in distinct contrast to the products obtained in dilute acid solutions, in which 5-formyl-2-furoic acid is produced in very low yield, whereas reductic acid is formed in yields in excess of 10%. 

Other authors suggested that catechins are converted to glucuronyl derivatives in the intestinal mucosa and are further metabolized by methylation, sulfation and conjugation with glucuronic acid, sulfate and glycine [101]. 

Hemicellulose. The hemicelluloses consisting of hexoses, pentoses, and uronic acids may be separated into two fractions, A and B. Hemicellulose B usually contains a higher proportion of uronic acid, mainly 4-methyl-D-glucuronic acid, than the A fraction. This methyl derivative of D-glucuronic acid is most frequently isolated in combined form as the... 

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