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Water-soluble Compounds (water-soluble + compound)
Selected AbstractsChemInform Abstract: Preparation and Properties of a Huge, Crystalline, and Water-Soluble Compound (C72H132N12Br6S12) That Possesses Six Carbenium Salt Units.CHEMINFORM, Issue 2 2002Juzo Nakayama Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] The purification, crystallization and preliminary structural characterization of PhzM, a phenazine-modifying methyltransferase from Pseudomonas aeruginosaACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 9 2006Neelakshi Gohain Pyocyanin, phenazine-1-carboxylic acid and more than 70 related compounds collectively known as phenazines are produced by various species of Pseudomonas, including the fluorescent pseudomonad P. aeruginosa, a Gram-negative opportunistic pathogen in humans and animals. P. aeruginosa synthesizes a characteristic blue water-soluble compound called pyocyanin (1-hydroxy-5-methyl-phenazine). Two enzymes designated PhzM and PhzS are involved in the terminal steps of its synthesis and very little is known about these enzymes. In this study, PhzM, a dimeric S -adenosylmethionine-dependent methyltransferase, was purified and crystallized from PEG 3350/sodium cacodylate/sodium citrate pH 6.5. The crystals belong to space group P1, with unit-cell parameters a = 46.1, b = 61.8, c = 69.6,Å, , = 96.3, , = 106.6, , = 106.9°. They contain one dimer in the asymmetric unit and diffract to a resolution of 1.8,Å. Anomalous data to 2.3,Å resolution have been collected from seleno- l -methionine-labelled PhzM. [source] Mechanisms affecting the dissolution of nonaqueous phase liquids into the aqueous phase in slow-stirring batch systemsENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 3 2001Mathias Schluep Abstract Understanding the kinetics of the exchange processes between nonaqueous phase liquids (NALs) and water is important in predicting the fate of anthropogenic compounds such as petroleum hydrocarbons, i.e., benzene, toluene, ethylbenzene, and xylene (BTEX) as well as polynuclear aromatic hydrocarbons (PAHs). Exchange processes occurring in the environment resemble the experimental setup of the slow-stirring method (SSM) designed to determine solubilities and octanol-water partition coefficients. Data obtained from SSM experiments for diesel fuel compounds are interpreted by a linear transfer model that is characterized by an aqueous molecular boundary layer and the water/NAPL equilibrium partition coefficient. For the chosen experimental setup, the boundary layer thickness is 2.42 × 10,2 cm. Typical equilibration times lie between 1 and 2 d. Due to the temperature dependence of the aqueous diffusivity, this time increases with decreasing temperature. Transport within the NAPL phase can slow down the exchange process for the more water-soluble compounds (e.g., benzene) provided that the stirring rate exceeds a critical value. [source] Uremic Toxins: Removal with Different TherapiesHEMODIALYSIS INTERNATIONAL, Issue 2 2003Raymond C. Vanholder A convenient way to classify uremic solutes is to subdivide them according to the physicochemical characteristics influencing their dialytic removal into small water-soluble compounds (<500 Da), protein-bound compounds, and middle molecules (>500 Da). The prototype of small water-soluble solutes remains urea although the proof of its toxicity is scanty. Only a few other water-soluble compounds exert toxicity (e.g., the guanidines, the purines), but most of these are characterized by an intra-dialytic behavior, which is different from that of urea. In addition, the protein-bound compounds and the middle molecules behave in a different way from urea, due to their protein binding and their molecular weights, respectively. Because of these specific removal patterns, it is suggested that new approaches of influencing uremic solute concentration should be explored, such as specific adsorptive systems, alternative dialytic timeframes, removal by intestinal adsorption, modification of toxin, or general metabolism by drug administration. Middle molecule removal has been improved by the introduction of large pore, high-flux membranes, but this approach seems to have come close to its maximal removal capacity, whereas multicompartmental behavior might become an additional factor hampering attempts to decrease toxin concentration. Hence, further enhancement of uremic toxin removal should be pursued by the introduction of alternative concepts of elimination. [source] Biorelevant media simulating fed state intestinal fluids: Colloid phase characterization and impact on solubilization capacityJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 8 2010Karen Kleberg Abstract The purpose of the present study was to study the impact of free fatty acid and monoglyceride level and ratio on the nanostructural composition and solubilizing capacity of media simulating fed state intestinal fluids (SIFs). SIFs, without or with oleic acid/monoolein (OA/MO) in ratios of 2:1 or 6:1 were composed and characterized by surface tension, dynamic light scattering, and cryogenic transmission electron microscopy. Additionally solubilizing capacities towards three poorly water-soluble compounds: danazol, fenofibrate, and cinnarizine, were assessed. The surface tension of the media was not affected by the OA/MO ratio but only determined by the total surfactant concentration. The media with no lipolysis products only contained micelles, whereas media with lipolysis products also contained vesicles and other colloidal structures. The structures in the 6:1 media were more numerous and more well-defined regarding shape and size. The nanostructural composition of the media did influence the solubilizing capacity toward fenofibrate and cinnarizine, but not toward danazol. The relative composition of SIFs is important for the solubilizing capacity of some drug compounds. The findings in this study suggest that the affinity of the drug to the different colloidal structures is determining for the solubility of the compound in the media. © 2010 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 99:3522,3532, 2010 [source] Evaluation of hydrate-screening methodsJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 7 2008Yong Cui Abstract The purpose of this work is to evaluate the effectiveness and reliability of several common hydrate-screening techniques, and to provide guidelines for designing hydrate-screening programs for new drug candidates. Ten hydrate-forming compounds were selected as model compounds and six hydrate-screening approaches were applied to these compounds in an effort to generate their hydrate forms. The results prove that no screening approach is universally effective in finding hydrates for small organic compounds. Rather, a combination of different methods should be used to improve screening reliability. Among the approaches tested, the dynamic water vapor sorption/desorption isotherm (DVI) method and storage under high humidity (HH) yielded 60,70% success ratios, the lowest among all techniques studied. The risk of false negatives arises in particular for nonhygroscopic compounds. On the other hand, both slurry in water (Slurry) and temperature cycling of aqueous suspension (TCS) showed high success rates (90%) with some exceptions. The mixed solvent systems (MSS) procedure also achieved high success rates (90%), and was found to be more suitable for water-insoluble compounds. For water-soluble compounds, MSS may not be the best approach because recrystallization is difficult in solutions with high water activity. Finally, vapor diffusion (VD) yielded a reasonably high success ratio in finding hydrates (80%). However, this method suffers from experimental difficulty and unreliable results for either highly water-soluble or water-insoluble compounds. This study indicates that a reliable hydrate-screening strategy should take into consideration the solubility and hygroscopicity of the compounds studied. A combination of the Slurry or TCS method with the MSS procedure could provide a screening strategy with reasonable reliability. © 2007 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 97:2730,2744, 2008 [source] Evaluation of drug precipitation of solubility-enhancing liquid formulations using milligram quantities of a new molecular entity (NME)JOURNAL OF PHARMACEUTICAL SCIENCES, Issue 11 2007Wei-Guo Dai Abstract A precipitation screening method using a 96-well microtiter plate was developed to evaluate in vitro drug precipitation kinetics of liquid formulations for poorly water-soluble compounds, using milligram quantities of compounds and milliliter volumes of biorelevant media. By using this method we identified three formulations showing distinct in vitro precipitation kinetics (fast, slow, and no precipitation) for a model new molecular entity (JNJ-25894934). The in vitro precipitation profiles in simulated intestinal fluid (SIF), fasted state simulated intestinal fluid (FaSSIF), and fed state simulated intestinal fluid (FeSSIF) were compared with those measured by a USP dissolution method, and with in vivo absorption at the fasted and fed states in canine pharmacokinetic (PK) studies. The precipitation kinetics of all three formulations in the initial hours measured by the screening method correlated to those determined by the USP method (R2,=,0.96). The PK results showed that the fast-precipitation formulation had the lowest bioavailability. However, a similar bioavailability was observed for the slow- and no-precipitation formulations. The oral bioavailability of JNJ-25894934 at the fed state was also significantly higher than that at the fasted state for all three formulations (p,<,0.05). In addition, the in vitro precipitation profiles in FeSSIF correlated better with in vivo absorption than those in SIF and FaSSIF. © 2007 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 96: 2957,2969, 2007 [source] Charcoal as a habitat for microbes and its effect on the microbial community of the underlying humusOIKOS, Issue 2 2000Janna Pietikäinen Wildfires produce a charcoal layer, which has an adsorbing capacity resembling activated carbon. After the fire a new litter layer starts to accumulate on top of the charcoal layer, which liberates water-soluble compounds that percolate through the charcoal and the unburned humus layer. We first hypothesized that since charcoal has the capacity to adsorb organic compounds it may form a new habitat for microbes, which decompose the adsorbed compounds. Secondly, we hypothesized that the charcoal may cause depletion of decomposable organic carbon in the underlying humus and thus reduce the microbial biomass. To test our hypotheses we prepared microcosms, where we placed non-heated humus and on top one of the adsorbents: non-adsorptive pumice (Pum), charcoal from Empetrum nigrum (EmpCh), charcoal from humus (HuCh) or activated carbon (ActC). We watered them with birch leaf litter extract. The adsorbing capacity increased in the order Pum Prospective Evaluation of the Change of Predialysis Protein-Bound Uremic Solute Concentration With Postdilution Online HemodiafiltrationARTIFICIAL ORGANS, Issue 7 2010Natalie Meert Abstract Although protein-bound uremic compounds have been related to outcome in observational studies, few current dialysis strategies provide more removal of those compounds than standard hemodialysis. We evaluated the evolution of protein-bound uremic solutes after a switch from high-flux hemodialysis to postdilution hemodiafiltration (n = 13). We compared predialysis solute concentration at 4, 5, and 9 weeks versus baseline for several protein-bound compounds and water-soluble solutes, as well as for ,2 -microglobulin. After 9 weeks of postdilution hemodiafiltration, a significant decrease versus baseline could be detected for total concentration of protein-bound solutes: p-cresylsulfate (3.98 ± 1.51,3.17 ± 1.77 mg/dL, ,20%, P < 0.01) and 3-carboxyl-4-methyl-5-propyl-2-furanpropionic acid (0.72 ± 0.52,0.64 ± 0.46 mg/dL, ,11%, P < 0.01). For the other protein-bound solutes, hippuric acid, indoleacetic acid, and indoxylsulfate, no change in total concentration could be detected. The concentration of the middle molecule, ,2 -microglobulin, decreased as well after 9 weeks of postdilution hemodiafiltration (24.7 ± 9.3,18.1 ± 6.7 mg/L, ,27%, P < 0.01). For water-soluble compounds, no significant change of concentration was found. Postdilution hemodiafiltration in comparison to high-flux hemodialysis provided significant reduction of predialysis concentration of protein-bound compounds, especially those with the highest protein binding, and of ,2 -microglobulin, by ,11 to ,27% in 9 weeks. [source]
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