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PubMed2001

Interaction of oxygen-sensitive luminescent probes Ru(phen)(3)(2+) and Ru(bipy)(3)(2+) with animal and plant cells in vitro. Mechanism of phototoxicity and conditions for non-invasive oxygen measurements.

Understanding the role of oxygen in the physiology, pathophysiology and radio- and chemosensitivity of animal cells requires accurate and non-invasive measurements of oxygen concentrations in the range of 0-2x10(-4) M, in cells in vitro or in vivo. High resolution 3D imaging techniques could be particularly useful in investigating tissue oxygenation in vivo and in model tissues (multicellular spheroids) in vitro. The goals of this work were to develop microscopy techniques and (i) to define conditions under which two oxygen-sensitive luminescent dyes, Ru(bipy)(3)(2+) (tris(2,2'-bipyridyl)ruthenium(II) chloride hexahydrate) and Ru(phen)(3)(2+) (tris(1,10-phenanthroline)ruthenium(II) chloride hydrate) can be used to probe oxygen concentrations within viable cells in vitro, when no phototoxic effects are evident, and (ii) to investigate the mechanism of phototoxicity once cell damage occurs. This report demonstrates that Ru(bipy)(3)(2+) and Ru(phen)(3)(2+) do not pass through intact biological membranes, do not cause measurable photodamage to plasma membranes at a concentration of 0.2 mM and, when loaded into endosomes, yield a strong luminescent signal. However, at an extracellular concentration of 1 mM, in the presence of 457-nm light, detectable amounts of both complexes accumulate at the plasma membrane and cause a loss of membrane integrity via a mechanism which may involve the generation of singlet oxygen.

2,2'-Dipyridyl↗
PubMed1977

[Carcinogenic polycyclic aromatics and metabolities as possible components of emissions (author's transl)].

In the last five years investigations of environmental samples by high resolution-low voltage mass spectrometry succeeded in better separations of aromatic compounds than with any other method before. In light fuel oil, in dusts from a highway and from towns and in the emissions of an oiloven for households namely at least 200 and up to 500 cyclic and polycyclic aromatic types of compounds of different molecular formulas were detected. From these many types of compounds contained oxygen and some sulfur. In the present study the question is discussed which known carcinogens can be among this abundance of types of compounds. For this purpose at first the carcinogenic polycyclic aromatics with formulas CnH2n+Z, CnH2n+ZO, CnH2n+ZO2 and CnH2n+ZS and the metabolites containing oxygen are listed according to the characteristic of the mass spectrometric method. Pure hydrocarbons there are 62 and sulfur containing 2 carcinogenic compounds with all together 29 different molecular formulas. In the following some comments are made on the methods of analyzing polycyclics. Judged by molecular formulas all samples mentioned can include the CnH2+Z- and the Cn H2n+ZS-carcinogens almost completely. Beyond that in the emissions of the oiloven the occurrence of all carcinogens containing oxygen is possible. Besides these emissions contain aromatics which have the same molecular formulas and perhaps the same structures as for metabolites of carcinogenic polycyclics have been determined up to now. Among these probably are also epoxides considered as proximate metabolites.

Anthracenes↗
PubMed1972

Biochemical effects of the hypoglycaemic compound diphenyleneiodonnium. Catalysis of anion-hydroxyl ion exchange across the inner membrane of rat liver mitochondria and effects on oxygen uptake.

1. The hypoglycaemic compound diphenyleneiodonium causes rapid and extensive swelling of rat liver mitochondria suspended in 150mm-NH(4)Cl, and in 150mm-KCl in the presence of 2,4-dinitrophenol and valinomycin. This indicates that diphenyleneiodonium catalyses a compulsory exchange of OH(-) for Cl(-) across the mitochondrial inner membrane. Br(-) and SCN(-) were the only other anions found whose exchange for OH(-) is catalysed by diphenyleneiodonium. 2. Diphenyleneiodonium inhibited state 3 respiration of mitochondria and slightly stimulated state 4 respiration with succinate or glutamate as substrate in a standard Cl(-)-containing medium. 3. Diphenyleneiodonium did not inhibit state 3 respiration significantly in two Cl(-)-free media (based on glycerol 2-phosphate or sucrose) but caused some stimulation of state 4. 4. In Cl(-)-containing medium diphenyleneiodonium only slightly inhibited the 2,4-dinitrophenol-stimulated adenosine triphosphatase and it had little effect in the absence of Cl(-). 5. The inhibition of respiration in the presence of Cl(-) is dependent on the Cl(-)-OH(-) exchange. 2,4-Dichlorodiphenyleneiodonium is ten times as active as diphenyleneiodonium both in causing swelling of mitochondria suspended in 150mm-NH(4)Cl and in inhibiting state 3 respiration in Cl(-)-containing medium. Indirect evidence suggests that the Cl(-)-OH(-) exchange impairs the rate of uptake of substrate anions. 6. It is proposed that stimulation of state 4 respiration in the absence of Cl(-) depends, at least in part, on an electrogenic uptake of diphenyleneiodonium cations. 7. Tripropyl-lead acetate, methylmercuric iodide and nine substituted diphenyleneiodonium derivatives also catalyse Cl(-)-OH(-) exchange across the mitochondrial membrane. 8. Diphenyleneiodonium is compared with the trialkyltin compounds, which are also known to mediate Cl(-)-OH(-) exchange and which have in addition strong oligomycin-like effects on respiration. It is concluded that diphenyleneiodonium is specific for catalysing anion-OH(-) exchange and will be a useful reagent for investigating membrane-dependent systems.

Acetates↗
PubMed1999

Laboratory model of a petroleum migration barrier in arctic alaska

Child's Pad is a gravel construction pad that was contaminated with petroleum during oil-field service operations in Deadhorse, AK. As part of a remedial action plan, a buffer strip of uncontaminated sandy gravel was placed along certain sections of the pad boundary. A peroxygen formulation manufactured by Regenesis Copyright, sold as Oxygen Release Compound (ORC(R)), was placed in the buffer strips. The ORC was intended to supply oxygen to aerobic microorganisms capable of degrading petroleum. Tests were conducted in a 1/2 scale laboratory cell to determine the oxygen release characteristics of the ORC when subjected to expected subsurface flow rates of up to 0. 02 l/s (6.9 m/day). In laboratory tests, a zone of enhanced oxygen concentration was formed down-gradient from the ORC socks. Only during periods when the flow rate was less than 0.01-0.015 l/s (3. 5-5.2 m/day) was ORC-oxygen observed at monitoring points up-gradient or directly cross-gradient of the ORC. Conclusions from the laboratory study were that ORC may provide an aerobic zone in the Child's Pad barrier as far as 1 m directly down-gradient of the sock during periods of high flows (6.9 m/day). Copyright 1999 Elsevier Science B.V.

Journal Article↗
PubMed2003

Oxygen-promoted Pd(II) catalysis for the coupling of organoboron compounds and olefins.

Reported herein is a mild and efficient Pd(II) catalysis, leading to the formation of carbon-carbon bonds between a broad spectrum of organoboron compounds and alkenes. Molecular oxygen was employed to reoxidize the resultant Pd(0) species back to Pd(II) during catalytic cycles. This oxygen protocol promoted the desired Pd(II) catalysis, whereas it retarded competing Pd(0) catalytic pathways such as Heck or Suzuki couplings. [reaction: see text]

Alkenes↗
PubMed1987

Protein control of prosthetic heme reactivity. Reaction of substrates with the heme edge of horseradish peroxidase.

Incubation of horseradish peroxidase with phenylhydrazine and H2O2 markedly depresses the catalytic activity and the intensity, but not position, of the Soret band. Approximately 11-13 mol of phenylhydrazine and 25 mol of H2O2 are required per mol of enzyme to minimize the chromophore intensity. The enzyme retains some activity after such treatment, but this activity is eliminated if the enzyme is isolated and reincubated with phenylhydrazine. The prosthetic heme of the enzyme does not react with phenylhydrazine to give a sigma-bonded phenyl-iron complex, as it does in other hemoproteins, but is converted instead to the delta-mesophenyl and 8-hydroxymethyl derivatives. The loss of activity is due more to protein than heme modification, however. The inactivated enzyme reacts with H2O2 to give a spectroscopically detectable Compound I. The results imply that substrates interact with the heme edge rather than with the activated oxygen of Compounds I and II and specifically identify the region around the delta-meso-carbon and 8-methyl group as the exposed sector of the heme. Horseradish peroxidase, in contrast to cytochrome P-450, generally does not catalyze oxygen-transfer reactions. The present results indicate that oxygen-transfer reactions do not occur because the activated oxygen and the substrate are physically separated by a protein-imposed barrier in horseradish peroxidase.

Chemical Phenomena↗
PubMed1979

Photoactivation of the nematicidal compound alpha-terthienyl from roots of marigolds (Tagetes species). A possible singlet oxygen role.

The nematicidal compound alpha-terthienyl from roots of Tagetes species generates upon irradiation with near ultraviolet light reactive oxygen species on which the in vitro nematicidal activity depends. This system was studied by following the inhibition of glucose-6-phosphate dehydrogenase by photoactivated alpha-terthienyl and protection of the enzyme activity in the absence of oxygen and by various additions. Addition of mannitol, benzoate, superoxide dismutase or catalase did not have any effect nor did H2O2. This suggests that OH., O-.2, and H2O2 are not the reactive oxygen species involved. The enzyme was protected against photoactivated alpha-terthienyl in air-saturated solutions by singlet oxygen quenchers such as histidine, methionine, tryptophan, bovine serum albumin, and NaN3. Furthermore, inactivation of the enzyme was about 3.5 times faster in D2O than in H2O. When alpha-terthienyl in CH2Cl2 was irradiated in the presence of the olefin adamantylideneadamantane, a stable dioxetane was formed which decomposed to adamantanone when heated above its melting point. These results indicate a singlet oxygen-mediated process.

Animals↗
PubMed2004

Phytochemical analysis and in vitro antimicrobial activity of two Satureja species essential oils.

The phytochemical GC[sol ]MS analysis and in vitro antimicrobial activity of the essential oils of the aerial parts of Satureja montana L. and Satureja cuneifolia Ten., collected in Croatia were performed. The major compound of S. montana oil was the phenolic monoterpene carvacrol (45.7%). Other important compounds were the monoterpenic hydrocarbons p-cymene (12.6%), gamma-terpinene (8.1%) and the oxygen-containing compounds carvacrol methyl ether, borneol, thymol and thymol methyl ether. The volatile oil of S. cuneifolia was characterized as beta-cubebene (8.7%), limonene (8.3%), alpha-pinene (6.9%), spathulenol and beta-caryophyllene. The antimicrobial effects of S. montana and S. cuneifolia oils were found to have a broad spectrum activity against multidrug-resistant pathogens by the broth microdilution method. These oils were active against all the test strains, with the exception of Pseudomonas aeruginosa. Compared with S. cuneifolia, savory oil exhibited greater antimicrobial activity. The maximum activity of savory oil was observed against Escherichia coli, methicillin-resistant Staphylococcus aureus and against the yeast (Candida albicans). The essential oil of S. cuneifolia was also found to inhibit the growth of medically important pathogens such as S. aureus and E. coli. Fungicidal activity for both oils against C. albicans and S. cerevisiae was also observed.

Anti-Infective Agents↗
PubMed2004

Effect of 13-epi-sclareol on the bacterial respiratory chain.

13-epi-sclareol is a labdane-type diterpene isolated from the resinous exudates of the medicinal plant species Pseudognaphalium cheiranthifolium (Lam.) Hilliard et Burtt. and P. heterotrichium (Phil.) A. Anderb. This compound has antibacterial activity only against Gram-positive bacteria, showing a bactericidal and lytic action. The interaction of 13- epi-sclareol with the bacterial respiratory chain was analyzed. The compound inhibited oxygen consumption of intact Gram-positive cells, but not with Gram-negative bacteria. The compound inhibited NADH oxidase and cytochrome c reductase activities, while coenzyme Q reductase and the cytochrome c oxidase activities were not affected. These results suggest that the target site of 13-epi-sclareol is located between coenzyme Q and cytochrome c. Using cytoplasmic membrane fractions, the results of the analysis of the enzyme activities associated with the respiratory chain complexes were the same for both Gram-positive and Gram-negative bacteria, indicating that the compound has no access to the cytoplasmic membrane of intact Gram-negative bacteria. Thus, the Gram-negative envelope may act as a physical barrier that prevents the access of this compound to the site of action.

Anti-Bacterial Agents↗
PubMed2003

Chemical composition and in vitro evaluation of antioxidant effect of free volatile compounds from Satureja montana L.

As a part of an investigation of natural antioxidants from Dalmatian aromatic plants, in this paper we report a study of the antioxidant activity related to the chemical composition of savory free volatile compounds. Twenty-one compounds were identified in the essential oil without fractionation, representing 97.4% of the total oil. The major compound was phenolic monoterpene thymol (45.2%). Other important compounds were monoterpenic hydrocarbons p-cymene (6.4%) a nd gamma-terpinene (5.9%)and oxygen-containing compounds carvacrol methyl ether (5.8%), thymol methyl ether (5.1%), carvacrol (5.3%), geraniol (5.0%) and borneol (3.9%). The evaluation of antioxidant power was performed in vitro by the beta-carotene bleaching and thiobarbituric acid (TBA) methods. As determined with both methods, the total savory essential oil as well as different fractions or pure constituents containing hydroxyl group exhibited relatively strong antioxidant effect. The hydrocarbons, when isolated as CH fraction, showed the poorest effectiveness in spite the fact that this fraction contained gamma-terpinene, alpha-terpinene, p-cymene and terpinolene which previously were identified as potential antioxidants.

Antioxidants↗
PubMed2003

Effects of butyltin compounds on mitochondrial respiration and its relation to hepatotoxicity in mice and Guinea pigs.

Because the mechanisms responsible for the difference in toxicity between different experimental animal species remain unclear, the effects of tributyltin chloride (TBTC) and dibutyltin dichloride (DBTC) on mitochondrial respiration were compared among the livers of mice and guinea pigs in vitro and in vivo. Further, the levels of these butyltin compounds and their derivatives in the mitochondrial fractions of the hepatocytes were investigated in these animal species. Administration of TBTC and DBTC to mice resulted in the obvious elevation of serum enzymatic activities, as well as the inhibition of succinate-linked State 3 respiration in hepatic mitochondria at 24 h after administration. On the other hand, these metal compounds failed to induce such hepatotoxicity or to inhibit mitochondrial respiration in guinea pigs. There was no significant difference between mice and guinea pigs in the IC50 (metal concentration observed in 50% inhibition of mitochondrial respiration) of TBTC and DBTC against the succinate-linked State 3 respiration of hepatic mitochondria in vitro, although the mitochondrial respiration of succinate-linked State 3 was inhibited in the liver of mice treated with the metals in vivo. The levels of total butyltin compounds in the mitochondrial fractions of hepatocytes were higher in the mice than in the guinea pigs, and the main butyltin compound in the mitochondrial fractions was DBTC in both species at 24 h after TBTC or DBTC administration. The amount of sulfhydryl groups, which were capable of binding with DBTC, in mice hepatic mitochondria was twice as large as that in guinea pigs, and the affinity of DBTC for the isolated hepatic mitochondria was higher in mice than in guinea pigs in vitro. These results suggested that the induction of hepatotoxicity by TBTC and DBTC in vivo was closely associated with the depression of mitochondrial respiration and that the difference in susceptibility to the metal-induced mitochondrial damages between mice and guinea pigs might result from the high affinity of butyltin compounds, in particular DBTC, for hepatic mitochondria in mice containing higher levels of sulfhydryl groups, compared with guinea pigs.

Administration, Oral↗
PubMed1980

[Toxic, anaphylactoid, and sensitizing properties of mercaptoquinolinates, metals of the 8th and 3d group].

A study was made of sensitizing, toxic and anaphylactoid action of eitht compounds of metals belonging to groups VIII and III of the periodic system. It was established that the activity depends on the nature of the central atom in the electronic structure of a complex salt ligand. The mechanism of histamine release was shown to be similar to that of specific antigen and to be related to preservation of the respiratory processes, of the microtubular and cell cyclic nucleotide systems. The sensitizing action of the compounds was shown by the reactions of the immediate and delayed types. Moreover, its realization did not require the presence of high molecular carriers, thus indicating that the latter is formed in the body.

Allergens↗
PubMed1998

S-Transnitrosation reactions are involved in the metabolic fate and biological actions of nitric oxide.

S-Nitrosothiols are a group of potent, bioactive compounds that form through the reaction of nitric oxide (NO) with thiols in the presence of oxygen. These compounds are naturally occurring in vivo, stabilize NO and potentiate its biological effects. S-Nitrosoglutathione is the most abundant intracellular S-nitrosothiol, and the kinetics for its formation favors de novo synthesis. In this analysis, we studied the formation of S-nitrosothiols by S-transnitrosation, or exchange of -NO for -H between sulfur atoms; we synthesized S-nitroso-glutathionyl-Sepharose 4B beads (SNO-4B) as a reagent with which to measure S-transnitrosation reactions. We detected a maximum of 1.57 +/- 0.24 pmol NO/bead (n = 5) after S-nitrosation of the beads with acidified nitrite. The stability of the S-NO bond was dependent on temperature, but not pH over the 5 to 9 range (except at pH 9 at 37 degrees ), with an estimated t1/2 of 30 hr at 22 degrees C and of approximately 2 wk at 4 degrees C. We demonstrated that SNO-4B transfers -NO to glutathione and to cysteine rapidly and in a pH-dependent manner. The initial rate of transfer of -NO from SNO-4B to glutathione at room temperature was 0.53, 3.03 and 5.14 microM/min at pH 5.0, 7.4 and 9.0, respectively (P < .05). Under the same conditions, the initial rate of -NO transfer to cysteine was 0. 72, 3.71 and 4.69 microM/min at pH 5.0, 7.4 and 9.0, respectively (P < .05). There was no appreciable S-transnitrosation between SNO-4B and bovine serum albumin. We further demonstrated that SNO-4B evokes significant vasodilator and platelet inhibitory responses in plasma-free systems and activates platelet soluble guanylyl cyclase. These data suggest a mechanism by which to explain the metabolic fate and distribution of NO among thiol pools in the vasculature, and implicate S-transnitrosation at the cell surface in NO signal transduction.

Animals↗
PubMed2002

Novel FMN-containing rotenone-insensitive NADH dehydrogenase from Trypanosoma brucei mitochondria: isolation and characterization.

A rotenone-insensitive NADH dehydrogenase has been isolated from the mitochondria of the procyclic form of African parasite, Trypanosoma brucei. The active form of the purified enzyme appears to be a dimer consisting of two 33-kDa subunits with noncovalently bound FMN as a cofactor. Hypotonic treatment of intact mitochondria revealed that the NADH dehydrogenase is located in the inner membrane/matrix fraction facing the matrix. The treatment of mitochondria with increasing concentrations of digitonin suggested that the NADH dehydrogenase is loosely bound to the inner mitochondrial membrane. The NADH:ubiquinone reductase activity is insensitive to rotenone, flavone, or dicumarol; however, it was inhibited by diphenyl iodonium in a time- and concentration-dependent manner. Maximum inhibition by diphenyl iodonium required preincubation with NADH to reduce the flavin. More complete inhibition was obtained with the more hydrophobic electron acceptors, such as Q(1) or Q(2), as compared to the more hydrophilic ones, such as Q(0) or dichloroindophenol. Kinetic analysis of the enzyme indicated that the enzyme followed a ping-pong mechanism. The enzyme conducts a one-electron transfer and can reduce molecular oxygen forming superoxide radical.

Animals↗