Biologically active carbohydrates

Production of fine chemicals and active pharmaceutical ingredients (APIs) will also continue to benefit from the judicious application of biocatalysis, in many cases as part of multistep synthetic schemes. Of particular relevance is the increasing demand for chirally pure pharmaceuticals, driven by concerns about the unwanted side-effects often associated with racemic drugs. Another growth area is likely to be the production of biologically active carbohydrates, traditionally requiring complex and expensive chemistries for production, to be used as pharmaceuticals, in infant formula, and as nutritional supplements. 

Combinatorial methods for the identification of biologically active carbohydrates are evolving. Generation of random glycosylation-based libraries as heterogeneous mixtures have given way to focused libraries that employ discrete saccharide cores. 

Some years ago, we started a project aimed at the development of simple and efficient enzymatic methods for the synthesis of biologically-active carbohydrates on a preparative scale. The use of enzymes as catalysts for the synthesis of carbohydrates has many potential advantages, such as enabling selective, stereo specific syntheses with a minimum of reaction steps under mild conditions and in aqueous solutions in which carbohydrates are highly soluble. Moreover, many enzymes now can be produced in quantity by fermentation and can be immobilized and reused. 

Abou Zeid AH, Aboutabl FA, Sleem AA, El-Rafie HM. Water soluble polysaccharides extracted from pterocladia capiUacea and dictyopteris membranacea and their biological activities. Carbohydr Polym. 2014 113 62-6. 

The polysaccharides of the ginseng comprised 40 % (by weight) of the root. This class of compound was first isolated and documented in 1966 [20]. Most biologically active carbohydrates in ginseng are acidic polysaccharides, known as ginsan, which have the typical structure of pectin [21, 22]. 

Yamada H (1994) Pectic polysaccharides from Chinese herbs Structure and biological activity. Carbohydr Polymers 25 269-276... 

There are many different isomers of carbohydrates, but relatively few occur naturally. Hence, in the TLC analysis of sugars, the chromatographer is concerned with a limited number of biologically active carbohydrates. For a good discussion of the structure of carbohydrates of plants, consult Harborne (1984). For a similar discussion of the structure of carbohydrates of animals, consult Scott (1969). 

General.- A review has appeared on the purity assessment of biologically active carbohydrates, especially by h.p.l.c. 

Triiodothyronine (3, 5,3-L-triiodothyronine, T3) is a thyroid hormone. It is producedby outer ring deiodination of thyroxine (T4) in peripheral tissues. The biologic activity of T3 is 3-8 times higher than that of T4. T3 is 99.7% protein-bound and is effective in its free non-protein-bound form. The half-life of triiodothyronine is about 19 h. The daily tur nover of T3 is 75%. Triiodothyronine acts via nuclear receptor binding with subsequent induction of protein synthesis. Effects of thyroid hormones are apparent in almost all organ systems. They include effects on the basal metabolic rate and the metabolisms of proteins, lipids and carbohydrates. 

Synthesis and Biological Activities of Compounds Containing Fluorinated Carbohydrates. 186... 

Table II. Carbohydrate compositions (weight percentage) of individual oligomer peaks purified (QAE-Sephadex or HPLC ion-exchange separation, respectively) from mixtures of citrus pectin oligomers or B fruit extracts Compositions shown are for peaks whose biological activity is described in Figure 4. Uronic acid values are based on colorimetric assay. Proportions of neutral sugars were determined by GC and adjusted so that totals equal 100%. In fact, some oligomers (G7 peaks 8, 9 and 10. B extract peak 10) produced small (less than 1 % of the total integrated area), unknown peaks in the GC chromatograms.

The preparation of nucleosides by reaction between carbohydrates and heterocyclic bases is fundamental to the study of the important biological activity... 

Haase C, Seitz O (2007) Chemical Synthesis of Glycopeptides. 267 1-36 Hahn F, Schepers U (2007) Solid Phase Chemistry for the Directed Synthesis of Biologically Active Polyamine Analogs, Derivatives, and Conjugates. 278 135-208 Hansen SG, Skrydstrup T (2006) Modification of Amino Acids, Peptides, and Carbohydrates through Radical Chemistry. 264 135-162... 

In addition to terpenes (as described above), carbohydrates have also been used as substrates in domino metathesis reactions, the aim being to synthesize enan-tiopure polyhydroxylated carbocyclic rings. These structures are components of several biologically active compounds such as aminoglycoside antibiotics [254], inositol phosphates [255], and carbanucleosides [256]. An efficient entry to this skeleton was developed by Madsen s group using a domino RCM/CM of the carbohy-... 

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