triacetoneamine-n-oxyl and tempidon

Persistent and mobile chemicals (PMs) and per- and polyfluoroalkyl substances (PFAS) are groups of chemicals that have received recent global attention due to their potential health effects on the environment and humans. In this study, exposure to a broad range of PMs and PFAS was investigated in Flemish adolescents' urine samples (n = 83) using a suspect screening approach. For this purpose, three sample preparation methods were evaluated, and a basic liquid-liquid extraction was optimized for urine analysis based on the extraction efficiency of PMs (53-80%) and PFAS (>70%). In total, 9 PMs were identified in urine samples at confidence levels (CL) 1-3 and, among them, acetaminophen, 4-aminophenol, 2,2,6,6-tetramethyl-4-piperidone, trifluoroacetic acid (TFAA), sulisobenzone, ethyl sulfate, and 1,2-benzisothiazol-3(2H)-one 1,1-dioxide were confirmed at CL 1 and 2. In addition, the detection and identification of 2,2,6,6-tetramethyl-4-piperidone, 4-aminophenol, TFAA, and m-(2,3-epoxypropoxy)-N,N-bis(2,3-epoxypropyl) aniline (CL 3), has been reported for the first time in human urine in this study. For PFAS, only 2 compounds were identified at CL 4, implying that urine is not a suitable matrix for suspect screening of such compounds. A significant difference between sexes was observed in the detection rate of identified PMs, in particular for acetaminophen, 4-aminophenol, and sulisobenzone. The findings of this study can be used in future human biomonitoring programs, such as by including the newly identified compounds in quantitative methods or monitoring in other human matrices (e.g., serum).

Topics: Acetaminophen; Adolescent; Aminophenols; Aniline Compounds; Benzophenones; Fluorocarbons; Humans; Triacetoneamine-N-Oxyl; Trifluoroacetic Acid

Carotenoids, natural pigments widely distributed in algae and plants, have a conjugated double bond system. Their excitation energies are correlated with conjugation length. We hypothesized that carotenoids whose energy states are above the singlet excited state of oxygen (singlet oxygen) would possess photosensitizing properties. Here, we demonstrated that human skin melanoma (A375) cells are damaged through the photo-excitation of several carotenoids (neoxanthin, fucoxanthin and siphonaxanthin). In contrast, photo-excitation of carotenoids that possess energy states below that of singlet oxygen, such as β-carotene, lutein, loroxanthin and violaxanthin, did not enhance cell death. Production of reactive oxygen species (ROS) by photo-excited fucoxanthin or neoxanthin was confirmed using a reporter assay for ROS production with HeLa Hyper cells, which express a fluorescent indicator protein for intracellular ROS. Fucoxanthin and neoxanthin also showed high cellular penetration and retention. Electron spin resonance spectra using 2,2,6,6-tetramethil-4-piperidone as a singlet oxygen trapping agent demonstrated that singlet oxygen was produced via energy transfer from photo-excited fucoxanthin to oxygen molecules. These results suggest that carotenoids such as fucoxanthin, which are capable of singlet oxygen production through photo-excitation and show good penetration and retention in target cells, are useful as photosensitizers in photodynamic therapy for skin disease.

Topics: Carotenoids; Cytotoxins; Dermatologic Agents; Electron Spin Resonance Spectroscopy; HeLa Cells; Humans; Light; Photochemotherapy; Photosensitizing Agents; Singlet Oxygen; Skin Diseases; Triacetoneamine-N-Oxyl; Xanthophylls

A sewage sludge sample was pyrolyzed in a drop tube furnace at 500 degrees C and sweeping gas flow rate of 300cm(3)/min. Triacetonamine (TAA) was detected with GC/MS as major component in the resulting bio-oil using acetone as the absorption solvent and proven to be a product from the reaction of NH(3) in the bio-oil with the absorption solvent acetone. TAA yield increased with storage time and reached a level about 28.4% (% sludge fed, daf) after 175h. Since the reaction of pure NH(3) with acetone does not proceed, some species in the bio-oil must catalyze the reaction of NH(3) with acetone. TAA was isolated in a high yield (27.9%, daf) and high purity (80.4%) by column chromatography with different solvents, including mixed solvents, as eluants. The study revealed the possibility of sewage sludge as potential resource of TAA.

Topics: Gas Chromatography-Mass Spectrometry; Hot Temperature; Sewage; Triacetoneamine-N-Oxyl

Diesel exhaust [diesel exhaust particles (DEPs) and their extracts (DPE)] and ultraviolet A radiation (UVA) are two ubiquitous environmental factors that have been identified as essential risk factors for various benign or malignant human diseases, either alone or in combination with other agents.. We aimed to investigate the synergistic effects of DPE and UVA at low-dose exposures in human-hamster hybrid (AL) cells and their underlying mechanisms.. We exposed exponentially growing AL cells to DPE and/or UVA radiation with or without reactive oxygen species (ROS) quenchers and then assayed the cells for survival, mutation induction, apoptosis, and micronucleus generation. In addition, using a singlet oxygen (1O2) trapping probe, 2,2,6,6-tetramethyl-4-piperidone, coupled with electron paramagnetic resonance spectroscopy, we determined the production of 1O2.. Treatment of AL cells with DPE+UVA induced significant cytotoxic and genotoxic damage. In contrast, we found no significant damage in cells treated with either UVA or DPE alone at the same doses. Mutation spectra of CD59- mutants showed that treatment with DPE+UVA easily induces multilocus deletions. Sodium azide significantly inhibited both cellular and DNA damage induced by DPE+UVA treatment, whereas other ROS inhibitors had little protecting effect. Furthermore, we found a significant increase of 1O2 in the cells that received DPE+UVA treatment.. These findings suggest that UVA activated the genotoxicity and cytotoxicity of DPE in mammalian cells and that 1O2 played an important role in these processes.

Topics: Animals; Apoptosis; Cell Survival; Cricetinae; Humans; Hybrid Cells; Micronucleus Tests; Mutagenicity Tests; Particulate Matter; Singlet Oxygen; Triacetoneamine-N-Oxyl; Ultraviolet Rays; Vehicle Emissions

Although enhancement of ultrasound-induced cell killing by photodynamic reagents has been shown, the sonochemical mechanism in detail is still not clear. Here, comparison between sonodynamic effect and photodynamic effect with photosensitizers at a concentration of 10 microM on free radical formation and cell killing was made. When electron paramagnetic-resonance spectroscopy (EPR) was used to detect 2,2,6,6-tetramethyl-4-piperidone-N-oxyl (TAN) after photo-irradiation or sonication with 2,2,6,6-tetramethyl-4-piperidone (TMPD), the order of TAN formation in the photo-irradiated samples was as follows: rhodamine 6G (R6) > sulforhodamine B (SR) > hematoporphyrin (Hp) > rhodamine 123 (R123) > rose bengal (RB)>erythrosine B (Er) = 0; although there was time-dependent TAN formation when the samples were sonicated, no significant difference among these agents were observed. All these agents suppressed ultrasound-induced OH radical formation detected by EPR-spin trapping. Sensitizer-derived free radicals were markedly observed in SR, RB and Er, while trace level of radicals derived from R6 and R123 were observed. Enhancement of ultrasound-induced decrease of survival in human lymphoma U937 cells was observed at 1.5 W/cm(2) (less than inertial cavitation threshold) for R6, R123, SR and Er, and at 2.3 W/cm(2) for R6, R123, Er, RB and SR. On the other hand, photo-induced decrease of survival was observed for R6, Hp and RB at the same concentration (10 microM). These comparative results suggest that (1) (1)O(2) is not involved in the enhancement of ultrasound-induced loss of cell survival, (2) OH radicals and sensitizer-derived free radicals do not take part in the enhancement, and (3) the mechanism is mainly due to certain mechanical stress such as augmentation of physical disruption of cellular membrane by sensitizers in the close vicinity of cells and/or cavitation bubbles.

Topics: Electron Spin Resonance Spectroscopy; Free Radicals; Humans; Light; Oxygen; Photochemotherapy; Photosensitizing Agents; Piperidones; Rhodamines; Sonication; Spin Trapping; Triacetoneamine-N-Oxyl; U937 Cells; Ultrasonics

Earlier we described a novel cytochrome P450 (CYP) catalyzed metabolism of the 2,2,6,6-tetramethylpiperidine (2,2,6,6-TMPi) moiety in human liver microsomes to a ring-contracted 2,2-dimethylpyrrolidine (2,2-DMPy) [Yin, W., et al. (2003) Drug Metab. Dispos. 31, 215-223]. In the current report, evidence is provided for the involvement of 2,2,6,6-TMPi hydroxylamines and their one-electron oxidation products, the nitroxide radicals, as intermediates in this pathway. Nitroxide radicals could be converted to their corresponding 2,2-DMPy metabolites by "inactivated CYP3A4", as well as by a number of other heme proteins and hemin, suggesting that this is a heme-catalyzed process. The conversion of nitroxide radicals to the 2,2-DMPy products by CYP3A4 or hemin was accompanied by the generation of acetone in incubations, providing evidence that the three-carbon unit from 2,2,6,6-TMPi was lost as acetone. With one model 2,2,6,6-TMPi nitroxide radical, evidence for an alternate pathway, which resulted in the formation of an intermediate that incorporated two oxygen atoms from water of the incubation medium before collapsing to the 2,2-DMPy product, was also obtained. To account for both pathways, a mechanism involving interaction of the nitroxide radicals with heme iron (Fe(III)), followed by a homolytic scission of the N-O bond and transfer of the nitroxide oxygen to heme iron to form a perferryl-oxygen complex, is proposed. The nitrogen-centered 2,2,6,6-TMPi radical thus formed then precipitates the contraction of the piperidine ring via C2-C3 bond cleavage, and the resulting product further oxidizes to an exocyclic iminium ion (by the perferryl-oxygen complex); the latter may undergo capture by water from the incubation medium and eliminate the three-carbon unit via N-dealkylation. It remains to be determined whether this novel interaction of nitroxide radicals with heme iron has any relevance in regard to the known biological properties of these stable radical species.

Topics: Aerobiosis; Anaerobiosis; Carbon Monoxide; Cyclic N-Oxides; Cytochrome P-450 CYP3A; Cytochrome P-450 Enzyme System; Deferoxamine; Free Radicals; Heme; Hemin; Humans; Iron; Iron Chelating Agents; Microsomes, Liver; NADP; Nitrogen Oxides; Oxygen Isotopes; Piperidones; Recombinant Proteins; Spectrometry, Mass, Electrospray Ionization; Triacetoneamine-N-Oxyl

Low-energy visible light (LEVL) has previously been found to modulate various processes in different biological systems. One explanation for the stimulatory effect of LEVL is light-induced reactive oxygen species formation. In the present study, both sperm and skin cells were illuminated with LEVL and were found to generate singlet oxygen (1O2). The detection of 1O2 was performed using a trapping probe, 2,2,6,6-tetramethyl-4-piperidone, coupled with electron paramagnetic resonance spectroscopy. In addition, we have shown that, together with O2 generation, LEVL illumination increases the reductive capacity of the cells, which explains the difficulties encountered in 1O2 detection. The potential of visible light to change the cellular redox state may explain the recently observed biostimulative effects exerted by LEVL.

Topics: Animals; Electron Spin Resonance Spectroscopy; Fibroblasts; Light; Male; Mice; NIH 3T3 Cells; Oxidation-Reduction; Piperidones; Sheep; Singlet Oxygen; Spermatocytes; Spin Labels; Triacetoneamine-N-Oxyl

To study the alkaloids from Armeniaca mume Sieb.. The alkaloids were extracted with chloroform from 80% alcoholic extract and concentrated. Then they were transferred into aqueous solution and absorbed by macroporous cation exchange resin. The concentrated total eluent was extracted with chloroform. The alkaloids were purified by recrystallization with petroleum ether and sublimation. Then they were determined by Fourier Transform Infrared spectroscopy, Mass spectrometry and Nuclear magnetic resonance etc methods.. Two alkaloids were separated and their structures were elucidated as 2,2,6,6-tetramethyl-4-piperidone and tert-butylurea on the basis of spectral evidence.. They are new alkaloids from A. mume.

Topics: Alkaloids; Fruit; Molecular Structure; Piperidones; Plants, Medicinal; Rosaceae; Spectroscopy, Fourier Transform Infrared; Triacetoneamine-N-Oxyl

We describe herein a novel metabolic fate of the 2,2,6,6-tetramethyl-piperidine (2,2,6,6-TMPi) moiety to a ring-contracted 2,2-dimethyl pyrrolidine (2,2-DMPy) in human liver microsomal incubations. The existence of this pathway was demonstrated for three compounds (I-III) of varied structures suggesting that this may be a general biotransformation reaction for the 2,2,6,6-TMPi moiety. The 2,2-DMPy metabolites formed in incubations of the three compounds with human liver microsomes were characterized by online high performance liquid chromatography coupled to a high resolution hybrid quadrupole-time-of-flight mass spectrometer. Suggested elemental composition obtained from accurate mass measurements of the molecular ions and fragment ions of the metabolites clearly indicated the loss of a mass equivalent to C(3)H(6) from the parent 2,2,6,6-TMPi functionality. Additional accurate tandem mass spectrometry data indicated that one of the original two gem-dimethyl groups was intact in the metabolite structure. Proof of a ring-contracted 2,2-DMPy structure was obtained using (1)H-NMR experiments on a metabolite purified from liver microsomal incubations, which showed only two geminal methyl groups, instead of four in the parent compound. Two-dimensional correlation spectroscopy and decoupling experiments established aliphatic protons arranged in a pyrrolidine ring pattern. The fact that the formation of 2,2-DMPy metabolites in human liver microsomes was NADPH-dependent suggested that this novel metabolic reaction was catalyzed by the cytochrome P450 (P450) enzyme(s). Immunoinhibition studies in human liver microsomal incubations using anti-P450 monoclonal antibodies and experiments with insect cell microsomes containing individually expressed recombinant human P450 isozymes indicated that multiple P450 isozymes were capable of catalyzing this novel metabolic transformation.

Topics: Biotransformation; Catalysis; Humans; Magnetic Resonance Spectroscopy; Male; Mass Spectrometry; Microsomes, Liver; Piperidines; Piperidones; Pyrrolidines; Triacetoneamine-N-Oxyl

The high concentration of zinc in the hippocampal mossy fiber axon boutons is localized in the vesicles and is mobilized by exocytosis of the zinc-laden vesicles. Furthermore, the mammalian hippocampi contain metallothionein (MT) isoforms which regulate the steady state concentration of zinc, an important antioxidant. Indeed, zinc deprivation leads to an increased lipid peroxidation, reduces the activity of Cu++-Zn++ superoxide dismutase, and protect against oxidative stress such as exposure to ultraviolet A irradiation. By employing electron spin resonance (ESR) spectroscopy, we have demonstrated that rat hippocampal MT isoforms 1 and 2 were able to scavenge 1,1-diphenyl-2-picrylhydrazyl radicals (DPPH), hydroxyl radicals (*OH) generated in a Fenton reaction, and superoxide anions (O2*-) generated by the hypoxanthine and xanthine oxidase system. In addition, MT-1 isoform protected the isolated hepatocytes from lipid peroxidation as determined by thiobarbituric acid bound malondialdehyde. MT antibodies scavenged DPPH radicals, hydroxyl radicals and reactive oxygen species but not superoxide anions. The results of these studies suggest that although both isoforms of MT are able to scavenge free radicals, the MT-1 appears to be a superior scavenger of superoxide anions and 1,1-diphenyl-2-picrylhydrazyl radicals. Moreover, antibodies formed against MT isoform retain some, but not all, free radical scavenging actions exhibited by MT-1 and MT-2.

Topics: Animals; Bepridil; Biphenyl Compounds; Cells, Cultured; Electron Spin Resonance Spectroscopy; Free Radical Scavengers; Hippocampus; Hydroxyl Radical; Male; Metallothionein; Picrates; Piperidones; Protein Isoforms; Rats; Rats, Sprague-Dawley; Superoxides; tert-Butylhydroperoxide; Triacetoneamine-N-Oxyl

Although it is assumed from in vitro experiments that the generation of reactive oxygen species such as the singlet oxygen (1O2), the hydroxyl radical, and the superoxide anion are responsible for chromium(VI) toxicity/carcinogenicity, no electron spin resonance (ESR) evidence for the generation of 1O2 in vivo has been reported. In this study, we have employed an ESR spin-trapping technique with 2,2,6,6-tetramethyl-4-piperidone (TMPD), a specific 1O2 trap, to detect 1O2 in blood. The ESR spectrum of the spin adduct observed in the blood of mice given 4.8 mmol Cr(VI)/kg body weight exhibited the 1:1:1 intensity pattern of three lines with a hyperfine coupling constant A(N) = 16.08 G and a g-value = 2.0066. The concentration of spin adduct detected in the blood was 1.46 microM (0.1% of total Cr concentration). The adduct production was inhibited by the addition of specific 1O2 scavengers such as 1,4-diazabicyclo[2.2.2]octane and sodium azide to the blood. The results indicate that the spin adduct is nitroxide produced by the reaction of 1O2 with TMPD. This is the first report of ESR evidence for the in vivo generation of 1O2 in mammals by Cr(VI).

Topics: Animals; Chromium; Electron Spin Resonance Spectroscopy; Hydroxyl Radical; Indicators and Reagents; Male; Mice; Oxygen; Piperazines; Piperidones; Sodium Azide; Spectrophotometry, Atomic; Time Factors; Triacetoneamine-N-Oxyl

The objective of this study was to investigate the effect of singlet oxygen ((1)O2) scavengers on functional recovery and ascorbyl free radical (AFR) formation in isolated ischemic rat hearts. Hearts were subjected to 40 min. of global ischemia followed by 30 min. of reperfusion. Hemodynamics were measured as heart rate (HR), coronary flow (CF), left ventricular developed pressure (LVDP) and contractility (dP/dt). Electron paramagnetic resonance (EPR) spectroscopy was used to measure AFR release in coronary perfusate during the first two min. of reperfusion as a function of ROS scavengers. Relative to ischemic controls the administration of the (1)O2 scavengers 2,2,6,6-tetramethyl-4-piperidone x HCl (4-oxo-TEMP), carnosine (beta-alanyl-L-histidine) or a combination of the two significantly improved functional recovery as measured by LVDP. While no AFR signal was detected in coronary perfusate collected during preischemic perfusion with and without (1)O2 scavengers, the AFR background signal due to ischemia was significantly increased with the (1)O2 and *O2- scavengers. No such increase was observed with the hydroxyl radical (*OH) scavenger mannitol. Besides the AFR increase with the (1)O2 and *O2- scavengers the functional recovery was only significantly improved with the (1)O2 scavengers. In contrast to previous AFR studies we found with endogenous AFR that an increased AFR formation is not necessarily only reflecting increased oxidative stress but can also report improved functional recovery. Combining the hemodynamic data with increased AFR formation in the presence of several different ROS scavengers gives supportive evidence for (1)O2 also being involved in reperfusion injury.

Topics: Animals; Ascorbic Acid; Blood Flow Velocity; Blood Pressure; Carnosine; Diuretics, Osmotic; Electron Spin Resonance Spectroscopy; Free Radical Scavengers; Free Radicals; Heart; Heart Rate; Male; Mannitol; Models, Biological; Models, Chemical; Myocardium; Oxygen; Piperidones; Rats; Rats, Sprague-Dawley; Reperfusion Injury; Superoxide Dismutase; Time Factors; Tranquilizing Agents; Triacetoneamine-N-Oxyl

Retinal impairment is one of the leading causes of visual loss in an aging human population. To explore a possible cause for retinal damage in the human population, we have monitored DNA oxidation in human retinal pigment epithelial (RPE) cells after exposure to hydrogen peroxide (H2O2) or the quinolone antibacterial sparfloxacin. When H2O2- or sparfloxacin-exposed cells were further exposed to ultraviolet A (UVA) irradiation, oxidative damage to the DNA of these cells was greatly increased over baseline values. This RPE+pharmaceutical-UVA cell system was developed to mimic in vivo retinal degeneration, seen in mouse studies using quinolone and UVA exposure. DNA damage produced by sparfloxacin and UVA in RPE cells could be remedied by the use of antioxidants, indicating a possible in vivo method for prevention or minimization of retinal damage in humans

Topics: 8-Hydroxy-2'-Deoxyguanosine; Anti-Infective Agents; Antioxidants; Butylated Hydroxytoluene; Cyclic N-Oxides; Deoxyguanosine; DNA Damage; Epithelial Cells; Fluoroquinolones; Humans; Hydrogen Peroxide; Nitrogen Oxides; Pigment Epithelium of Eye; Piperidones; Sodium Azide; Triacetoneamine-N-Oxyl; Ultraviolet Rays

The conversion of singlet oxygen ((1)O2) to hydroxyl radical (*OH) during photosensitization of uroporphyrin (UP) in the presence of NADPH was examined by a spin-trapping technique with 5,5-dimethyl-1-pyrroline-N-oxide (DMPO). Significant electron spin resonance (ESR) signals of DMPO-OH adduct were observed during irradiation of the UP-NADPH system with visible light. Scavengers of *OH reduced the signal intensity to 3-30% of control, indicating that more than 70% of DMPO-OH results from freely diffusing *OH. The ESR signal was almost completely lost when quenchers of (1)O2 were added, and was enhanced when the amount of deutrated solvent was increased. The appearance of (1)O2, as determined by the oxidation of 2,2,6,6-tetramethyl-4-piperidone (TEMPD), was delayed with an increase in the concentration of NADPH, whereas the production of *OH was upregulated. These observations indicate that conversion of (1)O2 to *OH occurs quickly in the presence of NADPH. Hydrogen peroxide (H2O2) was produced (1)O2-dependently during irradiation of UP in the presence of NADPH. However, neither catalase nor desferrioxamine decreased the DMPO-OH signal, and addition of H2O2 did not increase the signal. SOD increased the signal only slightly. These results suggest that the production of *OH from (1)O2 involves neither superoxide anion radical nor H2O2.

Topics: Animals; Catalase; Cattle; Deferoxamine; Electron Spin Resonance Spectroscopy; Ganglionic Blockers; Hydrogen Peroxide; Hydroxyl Radical; Light; Models, Chemical; NADP; Oxygen; Piperidones; Time Factors; Triacetoneamine-N-Oxyl; Up-Regulation; Uroporphyrins

Although photoexcited TiO2 has been known to initiate various chemical reactions, such as the generation of reactive oxygen species, precise mechanism and chemical nature of the generated species remain to be elucidated. The present work demonstrates the generation of singlet oxygen by irradiated TiO2 in ethanol as measured by ESR spectroscopy using 2,2,6,6-tetramethyl-4-piperidone (4-oxo-TMP) as a 1O2-sensitive trapping agent. Under identical conditions, the superoxide ion was also detected by spin trapping agent 5,5-dimethyl-pyrroline-N-oxide (DMPO). Kinetic analysis in the presence of both 4-oxo-TMP and DMPO revealed that singlet oxygen is produced directly at the irradiated TiO2 surface but not by a successive reaction involving superoxide anion. The basis for this view is the fact that DMPO added in the mixture increased the signals responsible for 4-oxo-2,2,6,6-tetramethyl-1-piperidinyloxy (4-oxo-TEMPO), a reaction product of 4-oxo-TMP and 1O2. The detailed mechanism for the generation of 1O2 and superoxide ion by irradiated TiO2 and reactions between these species and DMPO are discussed.

Topics: Electron Spin Resonance Spectroscopy; Photosensitizing Agents; Piperidones; Reactive Oxygen Species; Spin Trapping; Superoxides; Titanium; Triacetoneamine-N-Oxyl; Ultraviolet Rays

Cytochrome P450 (P450)-dependent p-hydroxylation of aniline and o-deethylation of 7-ethoxycoumarin were examined in rat liver microsomes in the presence of radical scavengers. The addition of beta-carotene, a quencher of singlet oxygen species ((1)O(2)), suppressed the aniline hydroxylation, while the addition of sodium azide (NaN(3)) ((1)O(2) quencher) enhanced the reaction. No other reactive oxygen scavengers or chelating agents such as superoxide dismutase, catalase, dimethylsulfoxide, or deferoxamine altered the reaction. In contrast, the microsomal o-deethylation of 7-ethoxycoumarin was suppressed by the addition of NaN(3). (1)O(2) was detectable during the reaction of microsomes and NADPH by ESR spin-trapping when 2,2,6,6-tetramethyl-4-piperidone (TMPD) was used as a spin trap, and the (1)O(2) was quenched by the additions of beta-carotene, NaN(3), aniline, and 7-ethoxycoumarin. The enhancement effect of NaN(3) in the hydroxylation of aniline appeared to be due to the conformational change of P450 protein, which in turn enhances the binding of aniline to P450 in terms of the spectral dissociation constant (K(s)). In contrast, (1)O(2) appeared to be active in the o-deethylation of 7-ethoxycoumarin. On the basis of the results, the involvement of (1)O(2) in P450-dependent substrate oxygenations is proposed.

Topics: 7-Alkoxycoumarin O-Dealkylase; Aniline Compounds; Animals; beta Carotene; Coumarins; Cytochrome P-450 Enzyme System; Electron Spin Resonance Spectroscopy; Free Radical Scavengers; Male; Microsomes, Liver; NADP; Oxidation-Reduction; Oxygen; Piperidones; Rats; Rats, Sprague-Dawley; Singlet Oxygen; Sodium Azide; Spin Trapping; Triacetoneamine-N-Oxyl

"beta CATECHIN", a preparation containing green tea extract, ascorbic acid, sunflower seed extract, dunaliella carotene and natural vitamin E, has been designed as a model "universal antioxidant" that offers protection via its scavenging action on a wide range of free radicals, both water-soluble and fat-soluble. Reactive oxygen species like singlet oxygen, hydroxyl and superoxide radicals, are often generated in biological systems during photosensitized oxidation reactions. We report on the simultaneous effect of "beta CATECHIN" on active oxygen species generated during the photosensitized oxidation of riboflavin using 2,2,6,6-tetramethyl-4-piperidone (TMPD) as a "spin-trapping" agent. The intensities of the resulting stable nitroxide radical adduct, 2,2,6,6-tetramethyl-4-piperidone-1-oxyl (TEMPONE), were detected by electron spin resonance (ESR) spectroscopy. Results show simultaneous, nonspecific and complete scavenging action of reactive oxygen species generated in our in vitro model system by "beta CATECHIN". It is therefore suggested that "beta CATECHIN" could offer protection against free radical insult and in preventing cancer and other diseases that are mediated by reactive oxygen species.

Topics: Animals; Antioxidants; Cattle; Electron Spin Resonance Spectroscopy; Free Radical Scavengers; Oxidation-Reduction; Photochemistry; Piperidones; Plant Extracts; Reactive Oxygen Species; Riboflavin; Spin Trapping; Triacetoneamine-N-Oxyl

The production of singlet oxygen by H2O2 disproportionation and via the oxidation of H2O2 by NaOCl in a neutral medium was monitored by spin trapping with 2,2,6,6 tetramethyl-4-piperidone (TMPone). The singlet oxygen formed in both reactions oxidized 2,2,6,6 tetramethyl-4-piperidone to give nitroxide radicals. However the production of nitroxide radicals was relatively small considering the concentrations of H2O2 and NaOCl used in the reaction systems. Addition of electron donating agents: ascorbate, Fe2+ and desferrioxamine leads to an increase in the production of nitroxide radicals. We assumed that a very slow step of the reaction sequence, the homolytic breaking of the O-O bond of N-hydroperoxide (formed as an intermediate product during the reaction of 1O2 with TMPone) could be responsible for the relatively small production of nitroxide radicals. Electron donating agents added to the reaction system probably raise the rate of the hydroperoxide decomposition by allowing a more rapid heterolytic cleavage of the O-O bond leading to a greater production of nitroxide radicals. The largest effect was observed in the presence of desferrioxamine. Its participation in this process is proved by the concomitant appearance of desferrioxamine nitroxide radicals. The results obtained demonstrate that the method proposed by several authors and tested in this study to detect singlet oxygen is not convenient for precise quantitative studies. The reactivity of TMPone towards O2.-/HO2. and .OH has been also investigated. It has been found that both O2.-/HO2. and .OH radicals formed in a phosphate buffer solution (pH 7.4, 37 degrees C), respectively by a xanthine-oxidase/hypoxanthine system and via H2O2 UV irradiation, do not oxidize 2,2,6,6 tetramethyl-4-piperidone to nitroxide radicals.

Topics: Ascorbic Acid; Cations; Cyclic N-Oxides; Deferoxamine; Electron Spin Resonance Spectroscopy; Free Radical Scavengers; Hydrogen Peroxide; Hydroxyl Radical; Iron; Oxidation-Reduction; Oxygen; Piperidones; Reactive Oxygen Species; Triacetoneamine-N-Oxyl; Ultraviolet Rays; Xanthine Oxidase

Sonodynamic therapy is a promising new modality for cancer treatment based on the synergistic effect on tumor cell killing by combination of a drug (typically a photosensitizer) and ultrasound. The mechanism of sonodynamic action was suggested to involve photoexcitation of the sensitizer by sonoluminescent light, with subsequent formation of singlet oxygen. In this work we studied the aqueous sonochemical reactions of the gallium-porphyrin derivative ATX-70, one of the most active sonodynamic agents found, using 50 kHz ultrasound. The experiments were carried out in the presence of 2,2,6,6-tetramethyl-4-piperidone hydrochloride (TMP), which reacts with singlet oxygen or .OH radicals to give the EPR-detectable nitroxide 2,2,6,6-tetramethyl-4-piperidone-N-oxyl (TMP-NO). Recently it has been suggested that the enhancement of TMP-NO yields in the presence of aqueous solutions of ATX-70 exposed to ultrasound was evidence for the formation of singlet oxygen in the system. Our results show that the surfactant cetyltrimethylammonium bromide (CTAB) can mimic the ATX-70-induced increase in the TMP-NO signal, but it fails to reproduce the behavior of ATX-70 in D2O: while the yields of TMP-NO in the presence of ATX-70 increase in D2O, the opposite effect was found with the surfactant CTAB. However, our data show that the increased TMP-NO yields in D2O are paralleled by an increased concentration of ATX-70 dimer, a form that is inactive in the photochemical generation of singlet oxygen. Our finding that the ATX-70-dependent enhancement of the TMP-NO signal was highest at approximately 20% O2, in both N2/O2 and argon/O2 mixtures, and decreased with increasing oxygen concentration is not compatible with the singlet oxygen mechanism. Finally, our results on the temperature dependence of the ATX-70-induced formation of TMP-NO are not consistent with the photochemical excitation of ATX-70 by sonoluminescent light: the ATX-70-dependent enhancement of TMP-NO signal increased with temperature in the range 10-25 degrees C, while the intensity of sonoluminescence of aqueous solutions both in multiple-bubble fields and in single-bubble experiments is known to decrease with increasing temperature.

Topics: Antineoplastic Agents; Deuterium; Electron Spin Resonance Spectroscopy; Free Radicals; Nitrogen Oxides; Oxygen; Piperidones; Porphyrins; Triacetoneamine-N-Oxyl; Ultrasonics; Water

The production of 2,2,6,6-tetramethyl-4-piperidone-N-oxyl by reaction of 2,2,6,6-tetramethyl-4-piperidone (TMPone) with ultrasonically generated active species in oxygenated solutions of hematoporphyrin (Hp) was studied by electron spin resonance spectroscopy. The nitroxide production rate in air-saturated TMPone solutions in phosphate-buffered saline of pH 9.0 was significantly higher in the presence of Hp than in its absence. The enhancement of nitroxide production by Hp was significantly inhibited in the presence of sodium azide or histidine in the solution. The production rate with Hp was doubled by substitution of deuterium oxide, while the rate without Hp increased only modestly. These results suggest that a substantial amount of active oxygen can be generated by ultrasound in aqueous solutions of Hp. Since the production rate was not reduced by mannitol and no nitroxide was produced in nitrogen-saturated solutions, it appears that hydroxyl radicals do not account for a major portion of the active oxygen species which reacted with TMPone to yield a nitroxide.

Topics: Electron Spin Resonance Spectroscopy; Hematoporphyrins; Piperidones; Reactive Oxygen Species; Superoxide Dismutase; Triacetoneamine-N-Oxyl; Ultrasonics

When hypericin was illuminated with 580 nm light in aqueous solution, the semiquinone radical, singlet oxygen, and superoxide anion radical were detected. The formation of the semiquinone radical and activated oxygen species and the transformation and competition between them depend on the quinone and oxygen concentrations, irradiation time and intensity, and the nature of substrate. In anaerobic solution containing a high concentration of the quinone, the semiquinone radical was predominantly photoproduced. In contrast, in aerobic solution, singlet oxygen is the principal product in the photosensitization of hypericin. Besides singlet oxygen, superoxide anion radical is generated by the quinone on illumination in aerobic solution via the reduction of oxygen by the semiquinone radical, but to a lesser extent than singlet oxygen. The generation of superoxide anion radical is significantly enhanced by the presence of electron donors.

Topics: Anthracenes; Antineoplastic Agents; Benzoquinones; Cyclic N-Oxides; Electron Spin Resonance Spectroscopy; Free Radicals; Light; Oxygen; Perylene; Photosensitizing Agents; Piperidones; Reactive Oxygen Species; Singlet Oxygen; Spin Labels; Superoxides; Triacetoneamine-N-Oxyl

The mechanism of lipid peroxidation catalyzed by bleomycin (BLM)-iron (Fe) complexes has been studied in vitro using sodium linoleate as a substrate. BLM-Fe(II)-O2 and BLM-Fe(III) complexes catalyze lipid peroxidation concomitantly with singlet oxygen evolution. The results from spin trapping methods and gas chromatography-mass spectroscopy (GCMS) analyses suggest that the initial step of lipid peroxidation catalyzed by BLM-Fe complexes is similar to that of soybean lipoxygenase, viz., hydrogen abstration. However, another mechanism might be concerned in the case of BLM-Fe(II)-O2 complex. BLM-Fe complexes are also capable of enhancing singlet oxygen evolution from the hydrogen peroxide (H2O2)-hypochlorite (OCl-) system.

Topics: Bleomycin; Cyclic N-Oxides; Electron Spin Resonance Spectroscopy; Humans; Kinetics; Linoleic Acids; Lipid Peroxidation; Lipoxygenase; Luminescent Measurements; Oxygen Consumption; Piperidones; Spin Labels; Triacetoneamine-N-Oxyl

The possible use of 2,2,6,6-tetramethyl-4-piperidone (TMPone) for the detection of singlet oxygen was investigated by gamma radiolysis and sonolysis of oxygen-saturated aqueous solutions. Formation of 2,2,6,6-tetra-methyl-4-piperidone-N-oxyl (TAN) was observed with both gamma radiolysis and sonolysis with a similar dependence on the concentration of TMPone up to 20 mM and a strong dependence on pH. In oxygen-saturated solutions the sonolysis of TMPone leads to the formation of the cyclic hydroxylamine (approx. 30% of the yield of TAN) while radiolysis does not. In the low pH range (5-6.5) and at high concentrations of OH radical scavengers (azide or formate), TAN is produced by sonolysis but not by radiolysis. Sonolysis of argon-saturated solutions of TMPone produces methyl radicals due to the high-temperature regions of the collapsing cavitation bubbles. The methyl radicals were detected by ESR (electron spin resonance) and spin trapping with 3,5-dibromo-2,6-dideuterio-4-nitroso-benzene sulfonate. Since the reaction of singlet oxygen with TMPone is also strongly dependent on pH, it does not seem likely that TMPone could be used for the detection of singlet oxygen in sonochemistry.

Topics: Cobalt Radioisotopes; Electron Spin Resonance Spectroscopy; Free Radical Scavengers; Gamma Rays; Hydrogen-Ion Concentration; Oxygen; Piperidones; Singlet Oxygen; Solutions; Triacetoneamine-N-Oxyl; Ultrasonics; Water

Photoexcited hematoporphyrin (Hp) induces the uncoupling of oxidative phosphorylation of mitochondria. The uncoupling was inhibited by pre-incubation of mitochondria with a fluorescent SH reagent, eosin-5-maleimide, which has been shown to react specifically with an essential SH group of the Pi/H+ symporter [Houstek and Pedersen, J Biol Chem 260: 6288-6295, 1985]. Eosin-5-maleimide labeled 33, 34.5 and 36 kDa proteins in untreated rat liver mitochondria. When eosin-5-maleimide was added after the treatment with Hp plus light, the proteins were not labeled. Singlet oxygen detection by the ESR spin trapping method during photoradiation of Hp was inhibited by amino acids. Cysteine inhibited it more efficiently than histidine, methionine, tryptophan, tyrosine or alanine under the conditions used. HPLC demonstrated that Hp plus light oxidizes cysteine to cystine together with a smaller amount of cysteinesulfinic acid. These results suggest that Hp plus light oxidizes the SH group of mitochondrial protein, probably the Pi/H+ symporter, with singlet oxygen as a mediator. The possibility of the uncoupling of oxidative phosphorylation through such a modification of the Pi/H+ symporter is discussed.

Topics: Amino Acids; Animals; Carrier Proteins; Chromatography, High Pressure Liquid; Cysteine; Electron Spin Resonance Spectroscopy; Eosine Yellowish-(YS); Hematoporphyrin Derivative; Hematoporphyrins; Light; Mitochondria, Liver; Oxidation-Reduction; Oxidative Phosphorylation; Oxygen Consumption; Phosphate-Binding Proteins; Photochemistry; Piperidones; Proteins; Rats; Rats, Inbred Strains; Triacetoneamine-N-Oxyl

In this paper we propose theoretical models for the conformations of triacetonamine and protonated triacetonamine (Vincubine, an anticancer chemotherapeutic agent) developed by quantum and molecular mechanics techniques. We discuss the theoretical factors which are involved in the stabilization of the conformations calculated by the MNDO, MM2 and COPEANE methods and show the relative percent abundance of each molecular shape. Graphic representations of the conformers are depicted.

Topics: Antineoplastic Agents; Models, Molecular; Molecular Conformation; Piperidones; Protons; Thermodynamics; Triacetoneamine-N-Oxyl

Topics: Animals; Blood Pressure; Cyclic N-Oxides; Male; Microcirculation; Muscles; Piperidines; Piperidones; Rats; Rats, Inbred Strains; Triacetoneamine-N-Oxyl; Vasodilation

Topics: Animals; Anxiety; Behavior, Animal; Female; Humans; Male; Methaqualone; Models, Psychological; Piperidines; Piperidones; Prognosis; Rats; Rats, Inbred Strains; Triacetoneamine-N-Oxyl

The authors carried out a pharmacokynetic study on the Bulgarian preparation Tempidone in rats. They examined resorption, distribution and excretion of the preparation in urine, bile and feces of rat after venous and oral administration. The experiments were carried out on 207 white male rats of the Wistar strain, weighting from 160 to 180 gm. Blood samples were obtained at various intervals from the onset of venous administration of the preparation in a dose of 100 mg/kg of body weight. After oral administration of the dose of 125 mg/kg of body weight in addition to blood samples other samples from brain, liver, stomach and intestines (small and large) were obtained as well. Excretion of Tempidone through the bile was examined after intraperitoneal administration of 250 mg/kg of body weight. They proposed pharmakynetic models after venous and oral administration of Tempidone. The obtained results gave evaluation for the rate, with which the distribution processes in the organism of rats occurred. Pharmacologic action of Tempidone coinceded in time with the creation and support of effective plasma concentrations. The wide distribution and preservation of Tempidone in the tissues suggested that it underwent the so called tissue binding.

Topics: Absorption; Administration, Oral; Animals; Dose-Response Relationship, Drug; Injections, Intravenous; Kinetics; Male; Piperidines; Piperidones; Rats; Time Factors; Tissue Distribution; Tosyl Compounds; Triacetoneamine-N-Oxyl

The authors carried out experiments on mice DBA/2 and BDF1 with leucosis L1210 and lung carcinoma of Lewis and found that psycotropic preparations tempidone and caffeine did not manifest antitumorous effect and toxicity after the used doses and scheme of treatment. Tempidone enhanced antitumorous action of small and mean doses of cyclophosphamide in mice with leucosis L1210. In the triple combination (tempidone, caffeine and cycl phosamide) the caffeine enhanced this action of tempidone without raising toxicity in mice with leucosis L1210, but not in mice with lung carcinoma of Lewis.

Topics: Animals; Caffeine; Carcinoma; Cyclophosphamide; Dose-Response Relationship, Drug; Drug Evaluation, Preclinical; Drug Interactions; Drug Synergism; Drug Therapy, Combination; Female; Leukemia L1210; Liver Neoplasms; Male; Mice; Mice, Inbred DBA; Mice, Inbred Strains; Neoplasm Transplantation; Neoplasms, Experimental; Piperidines; Piperidones; Psychotropic Drugs; Tosyl Compounds; Triacetoneamine-N-Oxyl

Tempidone is original Bulgarian preparation, synthetized in NIHFI (Zelayskov Bikova). The plasma level of the preparation is determined after single oral administration in doses of 60 and 120 mg and for a period of five days in a dose of 20 mg three times daily per a person. It is shown that tempidone is quickly resorbed and is excreted unchanged mainly in urine. The preparation does not cumulate. The content of tempidone in plasma is determined by the method of thin-layer chromatography, but in urine-spectrophotometricaly.

Topics: Administration, Oral; Biopharmaceutics; Dose-Response Relationship, Drug; Drug Evaluation; Humans; Piperidines; Piperidones; Time Factors; Triacetoneamine-N-Oxyl

Topics: Piperidines; Piperidones; Plants; Triacetoneamine-N-Oxyl

Topics: Animals; Barbiturates; Dogs; Drug Synergism; Drug Tolerance; Humans; Mice; Piperidines; Piperidones; Rats; Substance Withdrawal Syndrome; Substance-Related Disorders; Tosyl Compounds; Tranquilizing Agents; Triacetoneamine-N-Oxyl

Topics: Animals; Anti-Anxiety Agents; Central Nervous System; Male; Mice; Pentylenetetrazole; Piperidines; Piperidones; Receptors, Cholinergic; Strychnine; Tosyl Compounds; Triacetoneamine-N-Oxyl

Topics: Animals; Brain; Female; In Vitro Techniques; Ketoglutaric Acids; Male; Mitochondria; Mitochondria, Liver; Oxidative Phosphorylation; Piperidines; Piperidones; Rats; Tosyl Compounds; Triacetoneamine-N-Oxyl

Topics: Administration, Oral; Aggression; Animals; Avoidance Learning; Brain; Cats; Central Nervous System; Chlorpromazine; Columbidae; Drug Synergism; Ganglionic Blockers; Hexobarbital; Humans; Hydroxyzine; Injections, Intraperitoneal; Ketones; Mice; Morpholines; Motor Activity; Opipramol; Piperidines; Rabbits; Rats; Tosyl Compounds; Triacetoneamine-N-Oxyl

Topics: Animals; Chemistry, Pharmaceutical; Dogs; Lagomorpha; Mice; Pharmacy; Piperidines; Rabbits; Research; Toxicology; Triacetoneamine-N-Oxyl