Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Acetone”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 757 records · Page 42Linked to original sources
PubMed2005

Uptake and reaction kinetics of acetone, 2-butanone, 2,4-pentanedione, and acetaldehyde in sulfuric acid solutions.

This work presents a study of the uptake of acetone, 2-butanone (methyl ethyl ketone), 2,4-pentanedione, and acetaldehyde by sulfuric acid solutions with an aim at understanding the reactivity of carbonyl compounds present in the atmosphere toward acidic aerosols. Experiments were performed in a rotating wetted-wall reactor coupled to a mass spectrometer at room temperature (298 +/- 3 K) with 0-96 wt % H(2)SO(4) solutions. For all compounds, a reactive uptake was observed at high acidity (>or=64 wt % H(2)SO(4)). The corresponding reactions were found to follow a second-order kinetics, and their rate constants, k (M(-1) s(-1)) were found to increase exponentially with acidity. These rate constants and their variations with acid concentration were in good agreement with the kinetic behavior of acid-catalyzed aldol condensation reported in the organic chemical literature, except for 2,4-pentanedione. The results of this work suggest that aldol condensation should be too slow to account for the enhanced organic aerosol mass observed in smog chamber studies and should have an even smaller contribution under atmospheric conditions. The rate constants of other compounds, such as large aldehydes, remain however to be measured. However, in order to contribute significantly to organic aerosol formation, a liquid phase reaction would have to result in an uptake coefficient of the order of 10(-2).

Journal Article↗
PubMed2005

Olivary particles: unique carbon microstructure synthesized by catalytic pyrolysis of acetone.

Olivary (olive-shaped) carbon particles (OCPs) with a diameter of approximately 1.5-2 mum at the middle and a length of approximately 3-4 mum were synthesized by pyrolysis of acetone with metallic zinc as the catalyst at 600 degrees C. The content of the OCPs in the product is related to the catalyst, the pyrolysis temperature, and the time of ultrasonic dispersion before pyrolysis. The content of the OCPs was over 90% of the product under the optimum condition. Mg, Ni, Fe, Cu, Zn, and Cd powder were used as catalysts in the experiments, respectively, in which the metallic zinc powder was outstanding in the pyrolyzing process; the metallic iron and cadmium powder also improved the formation of the olivary carbon particles; however, magnesium, nickel, and copper could not operate the catalysis. Through Fourier transform infrared spectroscopy analysis, the mechanism of the formation of the olivary carbon particles was suggested to be an indirectly catalytic and self-assemble process. By high-resolution transmission electron microscope observation, an interesting arrangement of crystal planes of carbon was found that (002) planes of graphite near the surface are vertical to the surface of the OCPs and not parallel as usual.

Journal Article↗
PubMed2006

Functionalization of zeolite ZSM-5 by hydrosilylation and acetone coupling: synthesis, MAS NMR, and theory.

We report a two-step postsynthetic functionalization reaction of zeolite HZSM-5 that proceeds with high selectivity at room temperature. In the first step the framework acid sites of the zeolite are reacted with phenylsilane to replace the acidic proton with a hydrosilyl (-SiH3) group covalently linked to the framework. This group readily couples to acetone in a second step to form a framework-bound hydrosilyl isopropyl ether that is thermally stable at 473 K, but decomposes in the presence of moisture. We characterized these reactions using 29Si, 1H, and 13C MAS NMR, as appropriate. Theoretical modeling using density functional theory and cluster models of the zeolite acid site confirmed that both steps were exothermic and provided theoretical chemical shift values in excellent agreement with experiment.

Journal Article↗
PubMed2005

Mimicking dihydroxy acetone phosphate-utilizing aldolases through organocatalysis: a facile route to carbohydrates and aminosugars.

[reaction: see text] A practical and environmentally friendly organocatalytic strategy designed to mimic the DHAP aldolases has been developed and shown to be effective in the preparation of carbohydrates and aminosugars. (S)-Proline and (S)-2-pyrrolidine-tetrazole catalyzed the aldol reaction between dihydroxy acetone variants such as 1,3-dioxan-5-one and 2,2-dimethyl-1,3-dioxan-5-one with aldehydes to give the corresponding polyols in good yields with very high ees.

Aldehyde-Lyases↗
PubMed2006

Phytochemical and pharmacological studies on the acetonic extract of Marrubium globosum ssp. libanoticum.

A new natural labdane diterpene, marrulibanoside, was isolated from the acetonic extract of aerial parts of M. globosum Montbr. et Auch. ex Benth. ssp. libanoticum Boiss. (Lamiaceae). Its structure was determined by spectroscopic methods such as 1D and 2D NMR and mass spectrometry. Pharmacological studies have shown that the extract of M. globosum exerts anti-inflammatory effects in the rat paw oedema induced by carrageenin resulting in reduced paw swelling. This activity, which seems due to marrulibanoside, is a consequence of iNOS and COX-2 activities inhibition.

Animals↗
PubMed2004

Modeling nonionic aqueous solutions: the acetone-water mixture.

Several combinations of existing classical water and acetone models are studied by molecular dynamic simulations in order to sort out which models can reproduce available experimental data: enthalpies, pressure, densities, diffusion coefficients, and Kirkwood-Buff integrals. It turns out that all these properties, but the last, are rather well reproduced by all models, and with little numerical effort. By contrast, trials to measure by simulations the Kirkwood-Buff integrals lead to very long simulation times, thus revealing unexpected divergent behavior between the different models, such as phase separation, for example, and ultimately leading to a failure of any models combinations to reproduce these properties according to the experimental tendencies. It is argued herein that these deficiencies provide, in fact, an insightful picture of the microscopic structure of the solution, particularly into the relation between the hydrogen-bond network and the concentration fluctuations, as well as the role played by the solute in their spatial organization.

Journal Article↗
PubMed2005

On the evaluation of the Kirkwood-Buff integrals of aqueous acetone mixtures.

The Kirkwood-Buff integrals of acetone-water mixtures are determined using two experimental techniques: small-angle neutron scattering and vapor pressure measurements, in order to test the precision and reliability that can be achieved. The data are then compared with those previously reported by different authors, which tend to show considerable variation between them. The various possible sources of inaccuracies are pointed out, both from experimental origins and from the numerical treatment of the data. Comparison with recent simulation results allows to critically compare different models and provide some information about the microstructure of the aqueous mixture.

Journal Article↗
PubMed2006

Orientational correlations in liquid acetone and dimethyl sulfoxide: a comparative study.

The structure of acetone and dimethyl sulfoxide in the liquid state is investigated using a combination of neutron diffraction measurements and empirical potential structure refinement (EPSR) modeling. By extracting the orientational correlations from the EPSR model, the alignment of dipoles in both fluids is identified. At short distances the dipoles or neighboring molecules are found to be in antiparallel configurations, but further out the molecules tend to be aligned predominately as head to tail in the manner of dipolar ordering. The distribution of these orientations in space around a central molecule is strongly influenced by the underlying symmetry of the central molecule. In both liquids there is evidence for weak methyl hydrogen to oxygen intermolecular contacts, though these probably do not constitute hydrogen bonds as such.

Journal Article↗
PubMed2000

Effects of geranyl-geranyl-acetone administration before heat shock preconditioning for conferring tolerance against ischemia-reperfusion injury in rat livers.

The effect of geranyl-geranyl-acetone (GGA) administration before heat shock preconditioning on heat shock protein (HSP) 72 induction and on the acquisition of tolerance against ischemia-reperfusion Injury was studied in rat livers. Male Wistar rats were divided into four groups: a control group (group C); a GGA group (group G); a simple heat shock group (group VH); and a heat shock with GGA premedication group (group GH). Five-, 10-, and 15-minute periods of heat shock preconditioning at 42 degrees C were performed in groups VH and GH. Subgroups were determined according to the period of heat shock exposure. After a 48-hour recovery, rats in groups C, VH5, VH15, and GH5 received a 30-minute period of hepatic ischemia. Induction of HSP72, survival rates, and changes in biochemical and histologic parameters were compared among the groups. Five-minute heat shock preconditioning was not enough to Induce HSP72. However, livers in group GH5 expressed approximately the same amount of HSP72 as those in group VH15. The expression of HSP72 in group GH15 was stronger than that found in group VH15. The degree and location of HSP72 expression were not different between groups GH5 and VH15. Seven-day survival was significantly better in groups GH5 (16/16) and VH15 (15/16) than in group C (8/16) or VH5 (9/16). The recovery of adenosine triphosphate in liver tissue was faster, and the release of liver-related enzymes during reperfusion was lower in groups GH5 and VH15 than in group C or VH5. Administration of GGA before heat shock preconditioning augmented the induction of HSP72 by decreasing the threshold for triggering the stress response.

Alanine Transaminase↗
PubMed2000

A non-toxic heat shock protein 70 inducer, geranyl-geranyl-acetone, restores the heat shock response in gastric mucosa of protein-malnourished rats.

Acute gastric mucosal lesions caused by stress or noxious stimuli are important to consider in the management of critically or chronically ill patients. Protein malnutrition has been implicated as a risk factor for stress ulcer and subsequent complications in those patients. When male Wistar rats fed a 5% or 20% casein diet for 3 weeks were exposed to restraint and water-immersion stress, the low-protein diet significantly increased the ulcer index. The low-protein diet did not change the level of heat shock factor 1 (HSF1) in gastric mucosa but it did attenuate the HSF1 activation after exposure to the stress, resulting in the inhibition of HSP70 mRNA expression and HSP70 induction in gastric mucosa. HSP70 is crucial for the maintenance of cell integrity during pathophysiologic conditions; therefore the impaired HSP70 induction appeared to at least in part aggravate stress ulcer. We also tested whether a non-toxic HSP70 inducer, geranyl-geranyl-acetone (GGA), effectively improved the mucosal integrity by stimulating HSP70 induction under protein malnutrition. Intragastric administration of GGA (200 mg/kg twice a day) to the protein-malnourished rats for up to 1 week failed to stimulate the HSP70 induction. However, the administration of GGA (200 mg/kg twice a day) for 3 weeks restored HSP70 induction and induced higher resistance against stress ulcer as compared with results in vehicle-treated, normally nourished rats. Our results suggest that GGA may have a potential benefit for the prevention of stress ulcer in chronically or critically ill patients with protein malnutrition.

Animals↗
PubMed1997

Molecular cloning of acetone cyanohydrin lyase from flax (Linum usitatissimum). Definition of a novel class of hydroxynitrile lyases.

Acetone cyanohydrin lyase from Linum usitatissimum is a hydroxynitrile lyase (HNL) which is involved in the catabolism of cyanogenic glycosides in young seedlings of flax. We have isolated a full-length cDNA clone encoding L. usitatissimum HNL (LuHNL) from a cDNA expression library by immunoscreening. LuHNL cDNA was expressed in Escherichia coli and isolated from the respective soluble fraction in an active form which was biochemically indistinguishable from the natural enzyme. An open reading frame of 1266 base pairs encodes for a protein of 45,780 kDa. The derived amino acid sequence shows no overall homologies to the to date cloned HNLs, but has significant similarities to members of the alcohol dehydrogenase (ADH) family of enzymes. In particular, the cysteine and histidine residues responsible for coordination of an active site Zn2+ and a second structurally important Zn2+ in alcohol dehydrogenases are conserved. Nevertheless, we found neither alcohol dehydrogenase activity in LuHNL nor HNL activity in ADH. Moreover, well known inhibitors of ADHs, which interfere with the coordination of the active site Zn2+, fail to affect HNL activity of LuHNL, suggesting principally different mechanisms of cyanohydrin cleavage and alcohol oxidation. Interestingly, LuHNL like ADH and Prunus serotina (PsHNL) possesses an ADP-binding betaalphabeta unit motif, pointing to the possibility that the non-flavoprotein PsHNL and the flavoprotein LuHNL have developed from two independent lines of evolution of a common ancestor with an ADP-binding betaalphabeta unit.

Aldehyde-Lyases↗
PubMed2002

Pharmacological activities of crude acetone extract and purified constituents of Salvia moorcraftiana Wall.

The crude acetone extract of aerial parts of Salvia moorcraftiana Wall. was screened for various biological activities including Lemna bioassay, antifungal, antibacterial, leishmanicidal, insecticidal activities and brine shrimp cytotoxicity. It was found to possess strong phytotoxic activity against Lemna aequinoctials Welve. and moderate antifungal activity against animal and plant pathogens. The purified chemical constituents were tested for enzyme inhibition activity. Two constituents (compounds 3 and 8) were found to be effective inhibitors of alpha-glucosidase.

Animals↗
PubMed1978

Reversible conversion from Ca(2)+-ATPase activity to Mg(2)+- and Mn(2)+-ATPase activities of coupling factor purified from acetone powder of Rhodospirillum rubrum chromatophores.

It is known that the coupling factor purified from the acetone powder of chromatophores from Rhodospirillum rubrum shows ATPase activity in the presence of Ca(2)+, but not in the presence of Mg(2)+ or Mn(2)+. The present study deals with conditions, under which the Ca(2)+-ATPase activity is reversibly converted into Mg(2)+- and Mn(2)+-ATPase activites with the purified coupling factor. 1. Of the pH indicators tested, 6 kinds coverted the Ca(2)+-ATPase activity into Mg(2)+- and Mn(2)+-ATPase activities in the order, ethyl orange greater than tropaeolin 000 greater than or equal to metanil yellow greater than tropaeolin 00 greater than ethyl red greater than or equal to bromthymol blue. 2. Of the detergents tested, those other than Triton X-100 and Brij 58 caused the conversion described above; dodecylsulfonate was most effective, whereas dodecylpyridinium chloride was moderately effective. 3. 2,4-Dinitrophenol stimulated approximately two-fold the Ca(2)+-ATPase activity, but not the Mg(2)+- or Mn(2)+-ATPase activity at all. However, in the presence of dodecylpyridinium chloride, the pH indicator remarkably stimulated the Mg(2)+- and Mn(2)+-ATPase activities, accompanied with a partial inhibition of the Ca(2)+-ATPase activity. Methyl red and ethyl red showed similar effects. 4. All the nucleoside triphosphates tested can serve as the substrate. ATP was most effective for the Ca(2)+-ATPase activity, whereas dATP was most effective for the Mg(2)+- and Mn(2)+-ATPase activities induced by ethyl orange. 5. In the presence of ethyl orange, the ATPase activity was induced by various divalent cations in the following order of effectiveness, Mg(2)+ greater than Zn(2)+ greater than CO(2)+ greater than Mn(2)+ greater than Ni(2)+. 6. The mechanism of the reversible conversion from the Ca(2)+-ATPase activity to the Mg(2)+- and Mn(2)+-ATPase activities by pH indicators and detergents is discussed.

Bacterial Chromatophores↗
PubMedDate not supplied

Hypotensive effect of the hydralazine--acetone hydrazone in conscious rabbits: evidence for its back-conversion to hydralazine in vivo.

The hydralazine--acetone hydrazone (HAH) has previously been identified as a metabolite of hydralazine (H) in humans. We compared the hypotensive effects of HAH and H in groups of hypertensive rabbits. Both compounds caused a dose-dependent depressor response, with a potency ratio of HAH to H of approximately 0.2. Upon their intravenous administration to anephric rabbits, both H and HAH produced sustained concentrations in plasma of the H-pyruvic acid hydrazone, demonstrating that back-conversion of HAH to H occurred in vivo. We conclude that HAH is hydrolyzed in vivo to yield parent H. The levels of the H-metabolite, the pyruvic acid hydrazone, suggest that the hypotensive effect of HAH could be explained entirely by generation of H in vivo. This combined pharmacokinetic and pharmacodynamic approach can be applied to other H-hydrazones to evaluate their backconversion to H in vivo.

Animals↗
PubMed1993

Suppression of graft-versus-host disease by succinyl acetone in a rat allogeneic bone marrow transplantation model.

The efficacy of succinyl acetone (SA, 4,6-dioxoheptanoic acid) was explored in the allogeneic rat bone marrow transplant model of graft-vs.-host disease. Lethally irradiated Wistar Furth rats receiving Fischer 344 allogeneic bone marrow and spleen cells developed severe GVHD, resulting in mortality at 25-45 days posttransplant. Treatment for 14 days with 250 mg/kg/day of SA by Alzet osmotic pumps implanted subcutaneously 3 days before cell transfer prevented GVHD and produced long-term survivors that were allogeneic hematopoietic chimeras. SA doses below 250 mg/kg/day and treatment for less than 14 days were less efficacious. Initiation of SA therapy could be effectively delayed up to 7 days after BMT. Pharmacokinetic studies with i.v. bolus administration in normal CD rats revealed a plasma mean residence time that increased with dose and a systemic clearance that decreased with dose. Three dose-dependent half lives were apparent (ca. 7-18 min, 0.8-3 hr, and 12 hr). The s.c. bioavailability was ca. 82%. Relatively constant plasma SA levels were obtained with s.c. Alzet osmotic pumps, indicating no change in clearance with continuous exposure. Allogeneic BMT exerted no major influence upon SA clearance. These studies show that SA is a robust therapeutic agent that suppressed GVHD in the allogeneic rat BMT model under a variety of circumstances.

Animals↗