Dextran, ester derivatives

Ester derivatives of cellulose, chitin, dextran, amylose, and amylopectin were prepared utilizing the acid chloride derivatives described in Part B of the Experimental Section. 

Table I lists physical data for a number of the carbamate and ester derivatives of cellulose, chitin, amylose, amylopectin, and dextran synthesized as described in the Experimental Section. The solubility of the polysaccharide starting materials as well as that of the produced derivatives allows for macromolecular characterization through techniques including UV, NMR, IR, high pressure liquid chromatography, etc.

This method was reported before as a convenient way to couple drugs to dextran and starch (7). For the attachment of alcohols this method is obviously only practical when using the tri-ester derivatives in order to avoid intra- or inter-molecular reactions during the subsequent coupling procedures. However also with amine type drugs similar competitive side reaction may occur as will be illustrated. 

Reaction of carbohydrate with quaternary ammonium hydroxide Dextran acetate Ester derivative of dextran Dextran ether esters Mixed benzyl and butyl ethers... 

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. ... 

The tetrakis-sulphoxides (67) have been reported as a new type of PT catalyst in a solid-liquid mode, for example in 5n reactions of 1-bromo-octane. Nucleophilic substitutions of 1-bromo-octane and benzyl bromide are again the test reactions in a report on the use of the sucrose-ethylene oxide adducts (68a) as PT catalysts in both solid-liquid and liquid-liquid modes. The methacrylate ester derivative (68b) has been polymerized to a cross-linked gel that acts in a TC capacity for the same reactions. In a related approach some modified dextran anion exchangers carrying lipophilic substituents, such as the modified hydroxypropylated dextran gel shown in (69), have been synthesized and shown to catalyse displacement reactions including the alkyl bromide to iodide transformation under TC conditions. ... 

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. 

CMD and mixed derivatives based on CMD may be used for the fixation of antibiotics and enzymes on a polysaccharide matrix. A procedure was developed for amidation of CMD and its ethyl ester (CMDEE) with various aromatic amines in dioxane (100 °C), ethanol (78 °C), n-propanol (97 °C) and 2-propanol (82 °C) in the presence of a small amount of water [301]. CMDEE reacts with aliphatic and aromatic amines but in the case of amino acids the degree of amidation depends on the position of the amino moieties in the acids [302,303]. The DS decreases from S-, y-, /3, to a-amino acids. For the reaction with a-amino acids, carboxymethyl and carboxyethyl dextran azides are used [304],... 

Some alkanoic and alkenoic acids derived from biphenyl, stilbene and diphenylethane were reported to have potential antirheumatic and hypo-cholesterolaemic properties. Some of these compounds were later investigated by Milla and Grumelli for anti-inflammatory activity the only compound which showed activity was 3-(4-biphenylyl) acrylic acid, p-PhCgH4 GH = CH-CO-OH. Some of the alkylamine esters of this acid prepared by Carissimi , and the acid itself, were then examined for antiinflammatory activity in dextran oedema of the rat-foot, experimental granuloma in the rat, and synovial permeability in the rabbit, and for their ability to modify the reactions of subcutaneous connective tissue in mice. 

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. 

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. ... 

Many different types of esters and ethers of dextran pro dde macrmolectiles with diverse properties and negative, positive or neutral charges. Properties depend upon the type and degree of substitution, and the molecular weight of the dextran. The most widely used dextran derivative is obtained by the reaction of an alkaline solution of dextran with epichlorohydrin to give cross-linked chains. The product is a gel that is used as a molecular sieve. With its commercial introduction in 1959 by Pharmacia Fine Chemicals, Ltd, Uppsala, Sweden, cross-linked dextran revolutionized the purification and bio-separation processes. 

---