Mannitol 6-phosphate

Figure 7. Radioactivity scan of an electrophoretogram of a NaB[3H]i reduced hydrolysate of mannose-6-phosphate (top) and a mannose-6-phosphate containing yeast phosphomannan (37) (bottom. The procedure is described in the text. The compounds migrating more rapidly than mannitol-6-phosphate are derived from decomposition of the Dowex-50 resin used to catalyze the hydrolysis. The migration of authentic mannitol and mannitol phosphate were determined by direct reduction of mannose and mannose-6-phosphate, respectively.

Figure 8. Radioactivity scan of a paper electrophoretogram of NaB[3H7 s reduced hydrolysate of inhibitor glycopeptides (top) and glycopeptides from fi-galactosidase (bottom). Phosphorylated compounds could not be detected in peaks A and B or in the mannitol-6-phosphate region, C. (see the text for details).

The racemization apparently takes place before hydrolysis. Similar results have been obtained with D-xylitol 5-phosphate and n-mannitol 6-phosphate. 1,4-Anhydro-ribitol is also formed from the treatment of ribitol with dilute mineral acid. However, since the anhydro compounds are produced more readily from the phosphates than from the unsubstituted alditols, it has been suggested that the latter compounds are not formed as intermediate products. The mechanism of this reaction has been explained by assuming protonation of the ester oxygen atom, with subsequent intra-... 

Glucose-phosphate isomerase is one of the best studied enzymes catalyzing the interconversion of aldo- and ketohexose phosphates. An active site carboxyl group is a possible candidate for the base catalyzing the intramolecular proton transfer reaction. The affinity label 1,2-anhydro-D-mannitol 6-phosphate (8) inactivates the enzyme by forming an ester linkage between C-l of the affinity label and an active site carboxyl of a glutamic acid residue (98). 

Several of the intracellular teichoic acids are polymers of glycerol phosphate or ribitol phosphate. An unusual teichoic acid, composed of d-mannitol phosphate, and with pyruvic acid linked as an acetal to 0-4 and 0-5, has been isolated from Brevibacterium iodinum. ... 

P histidine-containing protein -i- D-mannitol phosphate S phosphohistidinoprotein -h D-mannose <1> (<1> enzyme II complex [1])... 

Rather uncommon are the two pyruvic acetal structures which have been identified in Klebsiella K12 capsular polysaccharides and in the teichoic acid of bacterium NCTC 9742 [10]. In the former case, a 4,5-0-(l-carboxyethylidene)- -D-galactofuranosyl residue was found at the side chain terminus of the hexa-saccharide repeating unit. In the latter case, the teichoic acid contains intra-catenally bound 2,3-0-(l-carboxyethylidene)-D-mannitol phosphate. No data about the configuration of these pyruvic acetals are available. 

In the human market, oral and parenteral dosage forms are prepared from the crystal. However, because of the extremely high potency, more dilute (0.1—10%) forms are avabable. These include dilutions with mannitol, triturations on dicalcium phosphate or resins, and spray-dried forms. Prices for these forms are driven by that of the crystal, which in early 1996 was ca 9.50/gram (95). Prices for the vitamin have risen during the first half of the 1990s. However, Htde growth in price beyond inflation is anticipated. 

In 1977, Kellogg and Fridovich [28] showed that superoxide produced by the XO-acetaldehyde system initiated the oxidation of liposomes and hemolysis of erythrocytes. Lipid peroxidation was inhibited by SOD and catalase but not the hydroxyl radical scavenger mannitol. Gutteridge et al. [29] showed that the superoxide-generating system (aldehyde-XO) oxidized lipid micelles and decomposed deoxyribose. Superoxide and iron ions are apparently involved in the NADPH-dependent lipid peroxidation in human placental mitochondria [30], Ohyashiki and Nunomura [31] have found that the ferric ion-dependent lipid peroxidation of phospholipid liposomes was enhanced under acidic conditions (from pH 7.4 to 5.5). This reaction was inhibited by SOD, catalase, and hydroxyl radical scavengers. Ohyashiki and Nunomura suggested that superoxide, hydrogen peroxide, and hydroxyl radicals participate in the initiation of liposome oxidation. It has also been shown [32] that SOD inhibited the chain oxidation of methyl linoleate (but not methyl oleate) in phosphate buffer. 

The alcoholysis of the cyclic phosphate of catechol by alditols can lead, after acid hydrolysis of intermediate, cyclic phosphates, to the selective formation of phosphoric esters of the primary hydroxyl groups in the alditols. Thus, erythritol and D-mannitol afford, after chromatographic purification of the reaction products, their 1-phosphates in yields of 31 and 38%, respectively.217 The method was used to convert riboflavine into riboflavine 5 -phosphate.218 1-Deoxy-1-fluoro-L-glycerol has been converted into the 3-(dibenzyl phosphate) in 54% yield by selective reaction with dibenzyl phosphorochloridate. 219... 

Osmolarity of perfusate solution The buffer osmolarity should be standardised to facilitate estimation of Peff values. Generally adjusted to physiological conditions of 290 mOsm/kg. (70 mM phosphate buffer) with 5.4 mM potassium chloride, 48 mM sodium chloride, 35 mM mannitol, and 10 mM D-glucose. Lane et al. [131] demonstrated the effect of hypersomolar perfusion on Tapp of ibuprofen in the in situ rat gut technique. Hypersomolar solutions tended to decrease Peff values, attributable to a reversed solvent drag effect. 

Excipients Cellulose, disodium hydrogen phosphate, hydroxypropyl cellulose, hydroxypropyl methylcellulose, lactose, mannitol, sodium lauryl sulfate, etc. 

Physically and chemically compatible up to 48 hours- Cimetidine mannitol potassium acetate potassium chloride potassium phosphate. 

Saline laxatives like MgS04, Mg(OH)2, Mg2 Citrate and Na+ Phosphates act via their osmotic pressure to retain water in the colon. Other osmotic laxatives are carbohydrates such as lactulose, glycerin, sorbitol, and mannitol. They are not absorbed and are resistant to digestion in the small intestine. Most agents are orally administered. It should be noted however that glycerin, sodium phosphates and sorbitol are formulated for rectal use. From lactulose lactic and acetic acids are formed by intestinal bacteria and apart from its osmotic effects it thus acidifies the content of the colon. The reduction of the pH stimulates motility and secretion. 

Partially thawed sheep placenta (ca. 400 g) were homogenized in 400 mL of lysate buffer (0.1 M phosphate, pH 7.8, containing 10 mM EDTA, 0.25 M mannitol, and 300 pM DDC) using Tissue Grinder. 

The main component of the adenosine diphosphate sugar fraction from a Salmonella typhimurium strain was unexpectedly found to be adenosine 5 -(D-mannitol 1-pyrophosphate)190 (45). Upon treatment with acid or with snake-venom pyrophosphatase, it produces adenosine 5 -phosphate and D-mannitol 1-phosphate these observations confirm the structure assigned. 

The competitive inhibition of aldolase by a number of structural analogs of D-ftuctose 1,6-diphosphate has been investigated.120 Among these analogs were 1,4-anhydro-DL-ribitol 5-phosphate, 1,4-anhydro-DL-xylitol 5-phosphate, 1,4-anhydro-D-arabinitol 5-phosphate, 2,5-anhydro-D-mannitol 1,6-diphosphate, and 2,5-anhydro-D-glucitol 1,6-diphosphate. Their respective, enzyme-inhibitor,... 

Apparent first-order rate constants for peroxynitrite decomposition in various buffers versus pH. When peroxynitrite is fully protonated at acidic pH, the decomposition rate is constant. The breakpoint in the curve identifies the pK, of peroxynitrite since a larger fraction present as an anion slows the rate of decomposition. In 50 mM potassium phosphate, the apparent pK, is at 6.8 and is not affected by temperatute (Koppenol, 1993). The rate of decomposition is not affected hy DMSO, mannitol, or ethanol. As shown in Fig. 28, many buffers can slightly accelerate the decomposition of peroxynitrite and the rate of decomposition reaches a maximum at high buffer concentrations. When these maximal rates are plotted as a function of pH, peroxynitrite exhibits a second pK, of approximately 8.0. 

Mannitol hexanitrate is obtained by nitration of mannitol with mixed nitric and sulfuric acids. Similarly, nitration of sorbitol using mixed acid produces the hexanitrate when the reaction is conducted at 0—3°C and at —10 to —75°C, the main product is sorbitol pentanitrate (117). Xylitol, ribitol, and L-arabinitol are converted to the pentanitrates by fuming nitric acid and acetic anhydride (118). Phosphate esters of sugar alcohols are obtained by the action of phosphorus oxychloride (119) and by alcoholysis of organic phosphates (120). The 1,6-dibenzene sulfonate of D-mannitol is obtained by the action of benzene sulfonyl chloride in pyridine at 0°C (121). To obtain 1,6-dimethanesulfonyl-D-mannitol free from anhydrides and other by-products, after similar sulfonation with methane sulfonyl chloride and pyridine the remaining hydroxyl groups are acetylated with acetic anhydride and the insoluble acetyl derivative is separated, followed by deacetylation with hydrogen chloride in methanol (122). Alkyl sulfate esters of polyhydric alcohols result from the action of sulfur trioxide—trialkyl phosphates as in the reaction of sorbitol at 34—40°C with sulfur trioxide—triethyl phosphate to form sorbitol hexa(ethylsulfate) (123). 

Brittle Rapid propagation of a crack throughout the material on application of stress, e.g., sucrose, mannitol, sodium citrate, lactose, and dicalcium phosphate. 

For the pharmaceutical product development scientist, there is clearly a need for objective information about the practical performance of different excipients and their various grades. In this chapter we set out to bring together the results of some of our ongoing evaluations of the physical and mechanical properties of excipients commonly used for the manufacture of solid oral dosage forms. In this particular article, we have chosen to focus on the fillers that are most commonly used in the manufacture of immediate release tablets microcrystalline cellulose (MCC), lactose, calcium phosphate, and mannitol (1). 

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