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PubMed1985

The role of reactive oxygen compounds derived from 6-hydroxydopamine for bone marrow purging from neuroblastoma cells.

6-Hydroxydopamine(6-OHDA), a specific neurotoxin against sympathetic nerve cells, is a drug already used for purging of bone marrow from neuroblastoma cells before autologous bone marrow transplantation. However, we could not detect significant differences in the toxicity of 6-OHDA against neuroblastoma and other tumor cells under the purging conditions clinically used. In contrast, bone marrow stem cells were much more resistant. The unspecific toxic effect of 6-OHDA is caused by H2O2 or H2O2-derived products which are generated by auto-oxidation in the incubation medium before a significant amount of 6-OHDA is taken up by the cells. Withdrawal of oxygen during the incubation period and subsequent incubation with an oxygen containing medium led to a more specific destruction of neuroblastoma cells which can take up 6-OHDA selectively.

Ascorbic Acid↗
PubMed1999

Abiotic formation of hydrocarbons and oxygenated compounds during thermal decomposition of iron oxalate.

The formation of organic compounds during the decomposition of iron oxalate dihydrate (IOD) was investigated as a possible analog for abiotic organic synthesis in geological systems. After heating at 330 degrees C for 2-4 days, IOD decomposed to a mixture of the minerals siderite and magnetite plus gas and non-volatile organic compounds. The organic products included an extremely large variety of compounds, making identification of individual reaction products difficult. However, the non-volatile products were dominated by several homologous series of alkylated cyclic compounds mostly containing a single aromatic ring, including alkylphenols, alkylbenzenes, alkyltetrahydronaphthols, and alkyltetrahydronaphthalenes. Traces of n-alkanols, n-alkanoic acids, n-alkanones, and n-alkanes were also identified. Carbon in the gas phase was predominantly CO2 (+CO?), with lesser amounts of light hydrocarbons to > C6 including all possible branched and normal isomers of the alkanes and alkenes. The organic products were apparently the result of two concurrent reaction processes: (1) condensation of the two-carbon units present in the initial oxalate moiety, and (2) Fischer-Tropsch-type synthesis from CO2 or CO generated during the experiment. Compounds produced by the former process may not be characteristic of synthesis from the single-carbon precursors which predominate in geologic systems, suggesting iron oxalate decomposition may not provide a particularly suitable analog for investigation of abiotic organic synthesis. When water was included in the reaction vessels, CO2 and traces of methane and light hydrocarbon gases were the only carbon products observed (other than siderite), suggesting that the presence of water allowed the system to proceed rapidly towards equilibrium and precluded the formation of metastable organic intermediates.

Ferrosoferric Oxide↗
PubMed2005

Identification and quantification of aerosol polar oxygenated compounds bearing carboxylic or hydroxyl groups. 2. Organic tracer compounds from monoterpenes.

In this study, a comparison is made of polar organic compounds found in the field with those produced in secondary organic aerosol from laboratory irradiations of natural hydrocarbons and oxides of nitrogen (NOx). The field samples comprised atmospheric particulate matter (PM2.5) collected at Research Triangle Park (RTP), NC, during the summer of 2003, and the laboratory samples originated from the photooxidation of the following monoterpenes: alpha-pinene, beta-pinene, and d-limonene. To determine the structural characteristics of the polar compounds, the filter samples were solvent extracted and derivatized using a technique based on single and multistep derivatizations. The resulting compound derivatives were analyzed by GC-MS in the methane-Cl and El modes. In addition to previously reported biogenic oxidation products (pinic acid, pinonic acid, norpinic acid, nopinone, and pinonaldehyde), seven multifunctional organic compounds were found in both field and laboratory samples. These compounds, which are proposed as possible atmospheric tracers for secondary organic aerosol from monoterpenes, were consistent with the following identifications: 3-isopropyl pentanedioic acid; 3-acetyl pentanedioic acid; 3-carboxy heptanedioic acid; 3-acetyl hexanedioic acid; 2-isopropyl-1,2-dihydroxybutanol; 4-isopropyl-2,4-dihydroxyhexanol; and 3-(2-hydroxy-ethyl)-2,2-dimethyl-cyclobutane carboxylic acid. Initial attempts have been made to quantify the concentrations of these tracer compounds on the basis of surrogate compound calibrations. The occurrence of these compounds in both laboratory and field measurements suggests that secondary organic aerosol originating from biogenic hydrocarbons are contributing to the regional aerosol burden in the southeastern United States. Several of these compounds also appear to contribute to the global aerosol burden in that they have also been identified in Europe and Brazil.

Aerosols↗
PubMed2002

Use of adsorbent and supercritical carbon dioxide to concentrate flavor compounds from orange oil.

Orange oil is composed largely of terpene hydrocarbons but is a source of flavor and fragrance compounds (oxygenated) that are present in low concentrations. To increase the ratio of oxygenated compounds to terpene hydrocarbons, orange oil was partially fractionated by adsorption of the oxygenated compounds onto porous silica gel, with full utilization of its adsorbent capacity, and then further purified by desorption into supercritical carbon dioxide. The desorption of 24 compounds was monitored by GC and GC-MS. Adsorption alone removed three-fourths of the terpene hydrocarbons, and fractional extraction by supercritical carbon dioxide (SC-CO(2)) improved the separation further. Response surface methodology was used in the experimental design, and regression analysis was used to determine the effects of process variables. Extraction at low temperatures and flow rates improved separation by SC-CO(2). Decanal was concentrated to 20 times that of the feed oil by using SC-CO(2) at 13.1 MPa, 35 degrees C, and 2 kg/h. The systems were operating at close to equilibrium conditions because of the fine dispersal of the oils and the excellent mass transfer properties of supercritical carbon dioxide.

Adsorption↗
PubMed1988

Microbiological effects of mouthrinses containing antimicrobials.

A number of mouthrinse formulations containing antimicrobials have been evaluated to determine their effectiveness as antiplaque and/or antigingivitis agents. These have included the bis-biguanides, phenols, quaternary ammonium compounds, oxygenating compounds, plant extracts, fluorides, antibiotics and antimicrobial combinations. These mouthrinses have often been tested as adjuncts to normal oral hygiene procedures as well as in the experimental gingivitis model. 2 agents in particularly, chlorhexidine gluconate and listerine, have been shown to both inhibit or reduce plaque accumulation and the severity of gingivitis. Chlorhexidine has been reported to reduce the accumulation of plaque by approximately 60% and the severity of gingivitis by 50-80% as determined by improvements in clinical indices. A 0.12% chlorhexidine gluconate rinse resulted in significant reductions after both 3 and 6 months use in the numbers of total anaerobes, total aerobes, streptococci, and actinomyces recovered from supragingival plaque. Listerine has been reported to retard the development of plaque by 45 to 56% and to reduce existing plaque by 39 to 48%. Gingivitis scores were reduced as much as 59%. Microbial studies have shown that the effect of listerine is exerted against the total microbial mass and results in an overall decrease in both the biomass and the activity. Long-term use of neither mouthrinse, chlorhexidine or listerine, resulted in the emergence of opportunistic or oral pathogens. Preliminary data obtained following the use of a novel mouthrinse consisting of a combination of povidone-iodine and hydrogen peroxide appears promising. This combination was more effective than was more effective than either single component alone in reducing gingivitis scores.(ABSTRACT TRUNCATED AT 250 WORDS)

Anti-Infective Agents, Local↗
PubMed2001

Evidence from the Pacific troposphere for large global sources of oxygenated organic compounds.

The presence of oxygenated organic compounds in the troposphere strongly influences key atmospheric processes. Such oxygenated species are, for example, carriers of reactive nitrogen and are easily photolysed, producing free radicals-and so influence the oxidizing capacity and the ozone-forming potential of the atmosphere-and may also contribute significantly to the organic component of aerosols. But knowledge of the distribution and sources of oxygenated organic compounds, especially in the Southern Hemisphere, is limited. Here we characterize the tropospheric composition of oxygenated organic species, using data from a recent airborne survey conducted over the tropical Pacific Ocean (30 degrees N to 30 degrees S). Measurements of a dozen oxygenated chemicals (carbonyls, alcohols, organic nitrates, organic pernitrates and peroxides), along with several C2-C8 hydrocarbons, reveal that abundances of oxygenated species are extremely high, and collectively, oxygenated species are nearly five times more abundant than non-methane hydrocarbons in the Southern Hemisphere. Current atmospheric models are unable to correctly simulate these findings, suggesting that large, diffuse, and hitherto-unknown sources of oxygenated organic compounds must therefore exist. Although the origin of these sources is still unclear, we suggest that oxygenated species could be formed via the oxidation of hydrocarbons in the atmosphere, the photochemical degradation of organic matter in the oceans, and direct emissions from terrestrial vegetation.

Journal Article↗
PubMed1980

Inhibition of human polymorphonuclear leukocyte chemotaxis by oxygenated sterol compounds.

When preincubated with certain oxygenated sterol compounds in lipoprotein-depleted serum [20% (vol/vol)], human polymorphonuclear leukocytes show inhibition of chemotaxis toward the synthetic dipeptide N-formylmethionylphenylalanine without alteration of random movement or loss of cell viability. These effects can occur at sterol concentrations as low as 6.25 microM and after as little as 5 min of preincubation, but they are increased at higher concentrations and longer preincubation times. The inhibition can be almost completely reversed by preincubation in lipoprotein-replete serum [human AB serum, 20% (vol/vol)] and may be partially corrected by addition of free cholesterol (0.125 mM) to the medium. These effects are unlikely to be due to inhibition of cellular sterol synthesis, competition for chemotaxin membrane binding sites, or deactivation of the leukocytes but they may be a consequence of insertion of the sterol molecule into the leukocyte plasma membranes.

Chemotaxis, Leukocyte↗
PubMed2000

LC-MS for the identification of oxygen heterocyclic compounds in citrus essential oils.

The oxygen heterocyclic compounds (coumarins, psoralens and polymethoxylated flavones) present in the nonvolatile residue of the essential oils of Mandarin, Sweet Orange, Bitter Orange, Bergamot and Grapefruit were analysed with an HPLC/API/MS system equipped with an APcI probe in positive mode. The use of hyphenated techniques, such as LC/MS provides a great information about the content and nature of constituents of natural complex matrices, such as essential oils. In this work, MS spectra were recorded at different voltages, to obtain structural information in addition to molecular weight information. The different response of the compounds identified has been also evaluated. The method allowed the confirmation of the identification of the main components of the fraction, previously reported for the different oils. MS characteristics of coumarins, psoralens and polymethoxylated flavones with different substitution patterns were determined on the basis of the response obtained with the APcI interface. Interface parameters were optimised to obtain a contemporaneous response for all the three classes of components.

Chromatography, High Pressure Liquid↗
PubMed1981

Effect of oxygenated sterol compounds on human bone marrow granulocytic progenitor cells.

Oxygenated sterol compounds are potent inhibitors of sterol and DNA synthesis in mammalian cells. We studied the effects of oxygenated sterols on human marrow granulocytic progenitor cells in vitro (CFU-C). 25-Hydroxycholesterol was found to be a potent inhibitor of sterol synthesis in marrow mononuclear cells, with 50% inhibition occurring at approximately 10(-7) M. This compound, as well as 6-ketocholestanol, 7-ketocholesterol, and 20 alpha-hydroxycholesterol, also demonstrated marked inhibition of CFU-C proliferation. The latter effect, which was not a result of direct cytoxicity of the compounds, was reversible by cholesterol, but not by mevalonic acid. We conclude that inhibition of sterol synthesis by oxygenated sterol compounds may be insufficient to explain their suppression of CFU-C proliferation.

Bone Marrow↗
PubMed2000

Microbial energetics and stoichiometry for biodegradation of aromatic compounds involving oxygenation reactions.

Oxygenation reactions significantly alter the energy and electron flows and, consequently, the overall stoichiometry for the microbial utilization of aromatic compounds. Oxygenation reactions do not yield a net release of electrons, but require an input of electrons to reduce oxygen molecules. The biodegradation pathway of phenanthrene as a model compound was analyzed to determine the impact of oxygenation reactions on overall stoichiometry using the half-reaction method. For individual oxygenation reactions, the half-reaction method for analyzing the electron and energy flows must be modified, because the reactions do not release electrons for synthesis or energy generation. Coupling the oxygenation reaction to subsequent reaction steps provides a net electron release for the coupled reactions. Modeling results indicate that oxygenation reactions increase the oxygen requirement and reduce the cell yield, compared to the conventional mineralization represented by hydroxylation reactions in place of oxygenations. The computed yields considering oxygenation reactions conform better to empirical yields reported in the literature than do yields computed by the hydroxylation single-step methods. The coupled-reaction model also is consistent with information about the ways in which micro-organisms that degrade aromatics accumulate intermediates, regulate degradation genes, and organize enzyme clusters.

Bacteria↗
PubMed2002

Diels-Alder and ene reactions of singlet oxygen, nitroso compounds and triazolinediones: transition states and mechanisms from contemporary theory.

Singlet oxygen, nitroso compounds and triazolinediones have similar electronic structures: they share a low lying LUMO, making them powerful electrophiles, and a high lying HOMO, orthogonal to the LUMO and consisting of an antibonding combination of lone paris. This bestows some nucleophilic character on these species. We describe a number of studies employing the best levels of theory currently available for systems of this size and demonstrate that the Diels-Alder and ene reactions of these three species are calculated to show subtle changes in mechanism. The calculations have been calibrated, wherever possible, by comparison to experimental observations including measured activation and reaction energies, regio- and stereo-selectivities, intermediates observed either spectroscopically or by trapping, and kinetic isotope effects.

Journal Article↗
PubMed1980

Molecular connectivity and gas chromatographic retention parameters.

The relation between gas chromatographic retention parameters and molecular connectivity has been investigated for several series of compounds including hydrocarbons, compounds containing oxygen functional groups (esters, aldehydes, ketones, alcohols and ethers) and drug molecules., With the oxygenated compounds good correlation was observed with the first order valence connectivity index, whilst for the other groups multiparameter equations were required for satisfactory correlation. The effect of column to column variation within a series was also investigated.

Alcohols↗
PubMedDate not supplied

Evaluation of antioxidant activities and antimutagenicity of turmeric oil: a byproduct from curcumin production.

Curcumin removed turmeric oleoresin (CRTO) was extracted with hexane concentrated to get turmeric oil, and that was fractionated using silica gel column chromatography to obtain three fractions. These fractions were analyzed by GC and GC-MS. Turmeric oil contained aromatic turmerone (31.32%), turmerone (15.08%) and curlone (9.7%), whereas fractions III has aromatic turmerone (44.5%), curlone (19.22%) and turmerone (10.88%) as major compounds Also, oxygenated compounds (5,6,8-10) were enriched in fraction III. Turmeric oil and its fractions were tested for antioxidant activity using the beta-carotene-linoleate model system and the phosphomolybdenum method. The fraction III showed maximum antioxidant capacity. These fractions were also used to determine their protective effect against the mutagenicity of sodium azide by means of the Ames test. All the fractions and turmeric oil exhibited a markedly antimutagenicity but fraction III was the most effective. The antioxidant effects of turmeric oil and its fractions may provide an explanation for their antimutagenic action.

Anti-Bacterial Agents↗