Lactobionic acid

Galactosylated chitosan prepared from lactobionic acid and chitosan with l-ethyl-3-(3-dimethylaminopropyl)-carbodiimideand N-hydroxysuccinimide was a good extracellular matrix for hepatocyte attachment [155] (Fig. 4). Furthermore, graft copolymers of galactosylated chitosan with poly(ethylene glycol) or poly(vinyl pyrrolidone) were useful for hepatocyte-targeting DNA carrier [156,157]. 

Lactobionic acid lOOmM Impermeant, suppresses cell swelling, Ca and Fe chelator... 

The solid-state structure of tetrabutylbis(2,3 4,6-diisopropylidene-2-keto-L-gulonato)distannoxane has been determined. The [Bu2Sn(IV)] complex of D-lactobionic acid also proved to be oligomeric, containing octa- (within the chain) and pentacoordinated (at the end of the chain) Sn centers in a ratio of 2 4. ... 

CN, coordination number. A CN of 5-6 means that the compound contains the Sn central atom in two different environments. 1, Bu2Sn0CH2CH20 2, methyl-4,6-0-benzylidene-a-D-glucopyranoside 3, methyl-4,6-0-benzylidene-a-D-mannopyranoside 4, o-lactobionic acid 5, o-galactose 6, Bu2Sn-DNA, maleic acid. 

Very precise kinetic experiments were performed with sponge Ni and Ru/C catalysts in a laboratory-scale pressurized slurry reactor (autoclave) by using small catalyst particles to suppress internal mass transfer resistance. The temperature and pressure domains of the experiments were 20-70 bar and 110-130°C, respectively. Lactitol was the absolutely dominating main product in all of the experiments, but minor amounts of lactulose, lactulitol, lactobionic acid, sorbitol and galactitol were observed as by-products on both Ni and Ru catalysts. The selectivity of the main product, lactitol typically exceeded 96%. 

The withdrawn hquid-phase samples were analyzed with an HPLC (Biorad Aminex HPX-87C carbohydrate coluttm. 1.2 ttiM CaS04 in deionized water was used as a mobile phase, since calcium ions improve the resolution of lactobionic acid [17]). Dissolved metals were analysed by Direct Current Plasma (DCP). The catalysts were characterized by (nitrogen adsorption BET, XPS surface analysis, SEM-EDXA, hydrogen TPD and particle size analysis). 

Some data fitting results are displayed in Figures 12.1 and 12.3. The general conclusion is that both models describe the behaviours of the main components, lactose and lactitol very well, both for sponge nickel and ruthenium catalysts. In this respect, no real model discrimination is possible. Both models also describe equally well the behaviour of lactobionic acid (D), including its concentration maximum when the reversible step is included (ks) (Figure 12.3). 

K. -G. Gerling, Large-scale production of lactobionic acid - used and new applications, International Dairy Federation, Whey proceedings of the second international whey conference (1998) 251. 

From a series of sulfated bis-aldonic acid amides with different alkyl spacer length, compound 34 was chosen for further evaluation as an antithrombotic. This compound was synthetically available in four steps from lactobionic acid (Scheme 7). Compound 34 had relatively high APTT values (42 U/mg) and antithrombotic activity, both of which decreased gradually when the number of methylene groups in the spacer was increased. It was thought to act via HCII and multiple sites in the intrinsic pathway of the coagulation cascade [64]. 

Xylose hydrogenation gave xylitol as a main product (selectivity typically over 99 %) and arabinitol, xylulose and xylonic acid as by-products, in lactose hydrogenation, the main product was lactitol (selectivity typically between 97 and 99 %) and lactulitol, galactitol, sorbitol and lactobionic acid were obtained as by-products. 

Figure 2. A. Consecutive xylose hydrogenation batches over sponge nickel catalyst (XA=xylonic acid). B. Influence of lactobionic acid (LBA) on lactose hydrogenation rate.

Lactobionic acid. This derivative is produced by oxidation of the free carbonyl group of lactose (Figure 2.25), chemically (Pt, Pd or Bi), electro-lytically, enzymatically or by fermentation. Its lactone crystallizes readily. Lactobionic acid has found only limited application its lactone could be used as an acidogen but it is probably not cost-competitive with gluconic acid-<5-lactone. It is used in preservation solutions for organs prior to transplants. 

There are three major chemical derivatives of lactose in which the /3 1-4 linkage remains unbroken. They are lactitol, produced by reduction lactulose, produced by isomerization and lactobionic acid, produced by oxidation. The synthesis and properties of these derivatives have been reviewed (Donar and Hicks 1982). 

Esters formed from lactobionic acid are not stable. However, lactobionic acid may be cyclized by dehydration to form a lactone which is reactive with amines to form stable amides (Scholnick and Pfeffer 1980). An extensive examination of the characteristics of nitrogenous derivatives such as N-dodecyl-lactobionamide or 1,6-dilactobionamido hexane was conducted, but no antimicrobial activity or other special use for these derivatives was identified. 

Certain aerobic organisms, notably of the Pseudomonas genus but also algae and yeasts, are capable of oxidizing lactose to lactobionic acid without hydrolysis to monosaccharides (Stodola and Lockwood 1947). Lactose dehydrogenase oxidizes lactose to lactobionic-5-lactone in the presence of a hydrogen acceptor the lactose is then hydrolyzed to lactobionic acid by lactonase (Nishizaka and Hayaishi 1962). 

Nishizuka, Y. and Hayaishi, 0.1962. Enzymic formation of lactobionic acid from lactose. J. Biol. Chem. 237, 2721-2728. 

Penicillium chrysogenum, oxidize lactose to lactobionic acid (Wallen-fels and Mulhotra 1961). 

Bacterial oxidations may yield useful products. Vinegar may be obtained from whey in the acetic acid fermentation. Lactobionic acid may be obtained in high yields by the action of Pseudomonas graveolens on the lactose in whey. Fermented whey can be used as a food or beverage. The reader who is interested in a more detailed discussion of these and some other fermentations employing whey as a substrate should consult the discussion by Marth (1970). 

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