Sugars in nature

Dextrose (D-glucose) is by far the most abundant sugar in nature. It occurs either in the monosaccharide form (free state) or in a polymeric form of anhydrodextrose units. As a monosaccharide, dextrose is present in substantial quantities in honey, fmits, and berries. As a polymer, dextrose occurs in starch, cellulose (qv), and glycogen. Sucrose is a disaccharide of dextrose and fmctose. 

D-Glucose is the most common sugar in Nature, and has always been found as the a- or >ff-pyranoside. The finding of -D-glucofuranosyl residues in the 0-antigen polysaccharide from" Erwinia amylovora T was therefore unexpected, and should be confirmed. 

Speculation concerning the origin of sugars in Nature has developed concurrently with the growth of the chemical knowledge of this group of substances. Thus, in 1870, Adolf Baeyer18 introduced the controversial,... 

A large number of sugars in natural products belong to the 6-deoxyhexose (6DOH) family, of which more than 70 different variants have been reported in plants, fungi and bacteria (Figure 8.1) [4b, 4c, 5]. These sugars are linked to the... 

Deoxy sugars are of wide occurrence as components of nucleic acids, natural glycosides, and antibiotics, and they were the subject of an earlier article by Hanessian in Volume 21. Here, de Lederkremer and Marino (Buenos Aires) provide a detailed update on the distribution of deoxy sugars in natural products, along with a survey of methods for their synthesis. 

Although the existence of furanose and open chain forms of amino sugars in natural products has not so far been reported, such derivatives have been prepared synthetically as reference compounds.M,Tl Glucosa-... 

A) It is the most common sugar in nature and is known as blood sugar. 

During the past nine years the subject of total synthesis of sugars and cyclitols has been vividly developed. The discovery of a large number of unusual sugars in nature—deoxy, amino, branched chain sugars (many of them components of antibiotics)—made their synthesis attractive. On the other hand, improvements in organic reagents and synthetic methods allowed a return to older preparations which could be now better performed. Finally, some synthetic ideas already described in this series, in the first chapter of the volume on the total synthesis of carbohydrates, are further expanded. 

Proton magnetic resonance measurements have shown thymine to be anti with respect to the sugar in naturally occurring polynucleotides contain-... 

Taxifolin-3 -0- -D-(6"-0-phenylacetyl)glueopyraoside (11), isolated from Pinus massoniana needles, is the first reported phenyl-acetylated sugar in nature. /S- -[ - -(p-HydroxyphenylacetyD-jfl-... 

Why is it not surprising that D-glucose is the most commonly found sugar in nature Hint. Look up structures for sugars such as D-galactose and D-mannose, and compare these with D-glucose.)... 

Leloir, L.F. The interconversion of sugar in nature. In Currents in biochemical research, p. 585-608. New York Interscience Publishers 1960... 

A number of the mono- and dimethyl derivatives of glucosamine and galactosamine have been prepared 309) as reference compounds for the determination of the linkage of the amino sugars in natural products. 

The major process for the synthesis of sugars in Nature is the autotrophic synthesis which we shall be studying later (Part Six). 

Intramolecular hemiacetal formation is common in sugar chemistry (Chapter 24). For example, glucose, the most common simple sugar in nature, exists as an equilibrium mixture of an acyclic pentahydroxyaldehyde and two stereoisomeric cyclic hemiacetals. The cyclic forms constitute more than 99% of the mixture in aqueous solution. 

Glucose (QH O, Section 24-1), the most common sugar in nature, is absolutely essential to all life on Earth. In many species it is the sole energy source for the major organs, including the entire central nervous system. All species synthesize glucose from smaller molecules. The process is called gluconeogenesis, and it employs a crossed aldol condensation (catalyzed by enzymes appropriately named aldolases) to construct a carbon-carbon bond between two three-carbon precursors. 

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