Ester of dextran

The sodium salts of sulphuric acid esters of dextran are used as anticoagulants for the same purposes as heparin. 

Iron dextran injection contains a complex of iron hydroxide with dextrans of average molecular weight between 5000 and 7000, and is used for the treatment of iron-defieiency anaemia in situations where oral therapy is ineffeetive or impractical. The sodium salt of sulphurie aeid esters of dextran, i.e. dextran sodium sulphate, has anti-eoagulant properties eomparable with heparin and is formulated as an injection for intravenous use. 

In addition, esters of dextran-bearing palmitoyl groups and phosphate functions can be used for the preparation of specifically modified liposomes, which are exploited for the entrapment of peptides such as hirudin, the most potent inhibitor of thrombin [105]. 

Dextran monosuccinate ester. A monosuccinate ester of dextran was prepared as described before by reacting the polysaccharide with succinic anhydride (30 meq./anhydroglucopyranoside unit) in presence of catalytic amounts of 4-dimethylamino pyridine. 

A remarkably different system comprised of a P-CD polymer and a guest polymer was recently described by Gref et al. [209], They mixed aqueous solutions of neutral P-CD epichlorohydrin polymer and a neutral lauryl ester of dextran, both of high molecular weights, and received no macroscopic gels but well-defined and... 

The preparations of dextran, and certain ethers and esters of dextran have been the subjects of about fifteen recent patents. The dextran (of L. mesenteroides or dextraniczim) may be precipitated first from the culture by the addition of ethanol or acetone, or the culture itself may be treated directly with the appropriate halide and sodium hydroxide in either a single stage or a two-stage procedure. The benzyl ether of dextran, formed by the reaction of dextran with benzyl chloride and sodium hydroxide at 75-185° for three to ten hours, is soluble in acetone and other solvents, and may be used in lacquers. Mixed ether and ester derivatives of dextran, e. g., benzyl and phthalate or butyl and benzoate, have been used for forming films, coatings or molded products. A preparation of dextran acetate has also been patented. ... 

Preparations of pancreatic ribonuclease, ribonuclease from Actinomyces rimosus, and the nuclease from Serratia marcescens have been covalently bound to 4 3-hydroxyethylsulphonylanisole-, 4j3-hydroxyethylsulphonylaniline, and 3-Cl-2-hydroxypropyl derivatives of dextran and dialdehyde-dextran and to the 4-aminobenzyloxymethyl ester of dextran.The yield and thermal stability of the modified nucleases depends both on the amount and the character of the functional groups activating the polysaccharide. 

Succinic esters of dextran have been prepared and transformed into the corresponding imidazolides, which react smoothly with alcohols or amines to yield the corresponding polymeric esters or amides. These activated amides may be of value for the preparation of polymer-drug adducts with a main backbone degradable to safe metabolites in the body fluids. 

Dextran and its derivates have found some applications in the medical field. Dextran sulphate has anticoagulant properties similar to those of heparin. Recent studies show antiviral properties of the sulphate esters of dextran, particularly in the treatment of the human immunodeficiency virus.Oral dextran sulphate has been used in Japan against arteriosclerosis for 20 years without harmful side-effects. Mercaptodextran is discussed for therapy of acute heavy-metal poisoning because it has a higher affinity for heavy metal ions such as silver, mercuric, cupric and auric ions than most other thiols and chelating agents. The properties of mercaptodextran are of interest regarding environmental clean-up of heavy metal contaminations. ... 

Synonyms Hydrogen sulfate Polydextran sulfate Sulfuric acid, dextran ester Definition Sulfuric acid ester of dextran Uses Binder in cosmetics pharmaceuticals (treatment for hyperlipidemia and ulcers, artery factor agent, blood coagulant) biotech applies. (DNA hybridization) industrial applies, (photographic emulsion additive)... 

Definition Sodium salt of the sulfuric acid ester of dextran... 

Leuconostoc mesenteroides dextrans have acquired considerable importance during recent years following the discovery that, when suitably degraded, they can be used as a substitute for blood plasma. Dextran sulphate is also used as a blood anticoagulant. Other ethers and esters of dextran find widespread applications in industry. 

Starch esters have been obtained by reactions of starch and carboxylic or sulfonic acid imidazolides in aqueous NaOH or nonaqueous solutions, as described in reference [226]. The esterification of dextran with butyric or palmitic acid using CDI in DMSO or formamide is discussed in reference [174]. 

The formation of two aqueous phases can be exploited in the recovery of proteins using liquid-liquid extraction techniques. Many factors contribute to the distribution of a protein between the two phases. Smaller solutes, such as amino acids, partition almost equally between the two phases, whereas larger proteins are more unevenly distributed. This effect becomes more pronounced as protein size increases. Increasing the polymer molecular weight in one phase decreases partitioning of the protein to that phase. The variation in surface properties between different proteins can be exploited to improve selectivity and yield. The use of more hydrophobic polymer systems, such as fatty acid esters of PEG added to the PEG phase, favors the distribution of more hydrophobic proteins to this phase. In Fig. 10.13, partition coefficients for several proteins in a dextran-PEG system are given [27]. 

Another potentially important fermentation is that producing butyric acid. The process is used industrially on only a small scale at present and details have not been disclosed. Many derivatives of butyric acid are used industrially the benzyl, methyl, octyl and terpenyl esters are used in the perfumery and essence trade and amyl butyrate, bornyl and isobornyl butyrates have been described as plasticizers for cellulose esters. Moreover vinyl butyrate is a possible ingredient of polymerizable materials. The mixed acetic and butyric acid esters of polysaccharides are also coming into favor. Cellulose acetate butyrate is marketed as an ingredient of lacquer and is less inflammable than the pure acetate. Dextran (see below) acetate butyrate may have similar uses. 

Synthesis of Dextran Esters with Bioactive Moieties (Prodrugs)... 

Fig. 9 Preparation of dextran phosphoric acid esters (phosphates) with polyphosphoric acid...

In contrast to the broad variety of applications of 1 - 4 and 1 3 linked glucans after reaction with (C2 to C4) carboxylic acid anhydrides and chlorides [159], the use of dextran esters of short chain aliphatic acids such as acetates or propionates is rather limited. According to the present knowledge, the commonly applied acetylation of polysaccharides with the acetic acid anhydrides or acetyl chlorides in the presence of triethylamine or pyridine as base does not lead to pure and soluble dextran acetate with significant DS values. In contrast, dextran propionates [160] and butyrates [161] can be... 

Chloroacetyl, methoxyacetyl and most importantly trifluoroacetyl moieties are used as impellers. Carboxylic acid esters of polysaccharides with almost complete functionalisation can be obtained. Thus, chloroform-soluble dextran stearates and dextran myristates with DS 2.9 are prepared by... 

Nevertheless, the reagent is still used for a large number of esterification reactions of dextran. The synthesis of dextran amino acid esters is achieved by conversion of the polysaccharide in DMSO with the N-ben-zyloxycarbonyl protected acids for 48 h at 20 °C using DCC and pyridine. 0-(N-B enzyloxycarbonylglycyl) dextran with DS 1.1, 0-(AT-benzyloxycarbo-nyl-aminoenanthyl) dextran with DS 2.2, and 0-(N-acelyl-i,-histidinyl)dcx-tran with DS 1.1 are accessible. Deprotection was achieved with oxalic acid and Pd/C [190,191],... 

Fig. 32 Conversion of dextran with hydroxyethyl methacrylate lactate using CDI yielding a carbonate-bound ester moiety...

---