Carbohydrates primary

Pivaloyl-p-D-glucopyranuronic acid has been prepared in order to identify it as a metabolite of pivaloyloxyalkyl-containing prodrugs, the acid grouping being introduced by catalytic oxidation. i Electrochemical oxidation of some carbohydrate primary alcohols at a nickel hydroxide electrode in alkaline solution has been developed as a route to uronic acids. Examples... 

The use of silver carbonate as the promoter has been successful for p-selective condensation between the (9-benzylated donor 5 and the reactive, non-carbohydrate primary alcohol 6 to give 7 (Scheme 3) [62] but it is less practical in other combinations [62-66]. Because activation by Koenigs-Knorr promoters produces an equimolar amount of water, loss of the donor as a result of hydrolysis is difficult to prevent even in the presence of drying agents [52]. 

The reaction of aldoses with nitric acid leads to the formation of aldaric acids by oxidation of both the aldehyde and the terminal primary alcohol function to carboxylic acid groups Aldaric acids are also known as saccharic acids and are named by substi tutmg aric acid for the ose ending of the corresponding carbohydrate... 

Nucleic acids are acidic substances present m the nuclei of cells and were known long before anyone suspected they were the primary substances involved m the storage transmission and processing of genetic information There are two kinds of nucleic acids ribonucleic acid (RNA) and deoxyribonucleic acid (DNA) Both are complicated biopolymers based on three structural units a carbohydrate a phosphate ester linkage between carbohydrates and a heterocyclic aromatic compound The heterocyclic aro matic compounds are referred to as purine and pyrimidine bases We 11 begin with them and follow the structural thread... 

Early investigators grouped alkaloids according to the plant families in which they are found, the stmctural types based on their carbon framework, or their principal heterocycHc nuclei. However, as it became clear that the alkaloids, as secondary metaboUtes (30—32), were derived from compounds of primary metabohsm (eg, amino acids or carbohydrates), biogenetic hypotheses evolved to link the more elaborate skeletons of alkaloids with their simpler proposed pregenitors (33). These hypotheses continue to serve as valuable organizational tools (7,34,35). 

Uses. The primary use of molasses is in animal feed. Molasses, which provides a carbohydrate source, salts, protein, vitamins, and palatabdity, may be used direcdy or mixed with other feeds. The carbohydrate content of 24.6 L (6.5 gal) of blackstrap molasses is considered to be equal to 0.035 m (one bushel) of com as measured by the energy produced from 0.035 m of com and the amount of molasses required to produce the same amount of energy. When molasses is less expensive than com, sales increase when the reverse is tme, sales decrease. 

Most carbohydrates have two kinds of reactive groups the carbonyl group and primary and secondary hydroxyl groups. 

A second family of carbohydrate-degrading enzymes, the lysozymes, produces synergistic antimetastatic activity when co-adrninistered with cisplatin [15663-27-1] to mice whose primary tumor had been surgically removed (51). 

Some of the original work in the carbohydrate area in particular reveals extensive protection of carbonyl and hydroxyl groups. For example, a cyclic diacetonide of glucose was selectively cleaved to the monoacetonide. A summary describes the selective protection of primary and secondary hydroxyl groups in a synthesis of gentiobiose, carried out in the 1870s, as triphenylmethyl ethers. 

ACOCH2CF3, porcine pancreatic lipase, THF, 60 h, 77% yield. This enzymatic method was used to acetylate selectively the primary hydroxyl group of a variety of carbohydrates. 

Air pollutants may enter plant systems by either a primary or a secondary pathway. The primary pathway is analogous to human inhalation. Figure 8-2 shows the cross section of a leaf. Both of the outer surfaces are covered by a layer of epidermal cells, which help in moisture retention. Between the epidermal layers are the mesophyll cells—the spongy and palisade parenchyma. The leaf has a vascular bundle which carries water, minerals, and carbohydrates throughout the plant. Two important features shown in Fig. 8-2 are the openings in the epidermal layers called stomates, which are controlled by guard cells which can open and close, and air spaces in the interior of the leaf. 

Chloroplasts are the site of photosynthesis, the reactions by which light energy is converted to metabolically useful chemical energy in the form of ATP. These reactions occur on the thylakoid membranes. The formation of carbohydrate from CO9 takes place in the stroma. Oxygen is evolved during photosynthesis. Chloroplasts are the primary source of energy in the light. 

Possibly the most serious nutrition problem in the United States is excessive food consumption, and many people have experimented with fad diets in the hope of losing excess weight. One of the most popular of the fad diets has been the high-protein, high-fat (low-carbohydrate) diet. The premise for such diets is tantalizing because the tricarboxylic acid (TCA) cycle (see Chapter 20) is the primary site of fat metabolism, and because glucose is usually needed to replenish intermediates in the TCA cycle, if carbohydrates are restricted in the diet, dietary fat should merely be converted to ketone bodies and excreted. This so-called diet appears to work at first because a low-carbohydrate diet results in an initial water (and weight) loss. This occurs because... 

---