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PubMedDate not supplied

Photostability of symphatomimetic agents in commonly used infusion media in the absence and presence of bisulfite.

Previous studies have indicated that epinephrine is photodegraded in sulfite-containing solutions by adrenochrome sulfonate. The present study was undertaken to investigate if the same degradation pattern is found for the symphatomimetic compounds isoprenaline, dopamine, and metaraminol. It was found that isoprenaline and dopamine followed the same degradation pattern as epinephrine--they are photodegraded more rapidly in the presence of bisulfite than in its absence, probably by formation of an aminochrome sulfonate. Metraminol was photostable under the given conditions. The photostability of isoprenaline, dopamine, and epinephrine was further investigated in the infusion media sodium chloride (9 mg/ml), glucose (50 mg/ml), Macrodex (dextran 70, 60 mg/ml, sodium chloride 9 mg/ml) and Ringer acetate. The influence of pH, conductivity, viscosity and media concentration were analyzed. In the presence of bisulfite it was found that Ringer acetate had a photodestabilizing effect, while Macrodex had a slight photoprotective effect, on the catecholamines. The pH of the media was shown to be the most important factor, a low pH being protective. Glucose had a destabilizing effect on epinephrine, dopamine, and isoprenaline in the absence of bisulfite.

Dextrans↗
PubMedDate not supplied

[Effect of lipophilic ortho-naphthoquinones on the growth of and production of peroxides by Leptomonas seymouri and Crithidia fasciculata].

The lipophilic o-naphthoquinones CG 8-935, CG 9-442, CG 10-248 and mansonones A, C, E and F inhibit growth of the trypanosomatids Leptomonas seymouri (LS) and Crithidia fasciculata (CF). The most active mansonones were E and F (I50, 0.1-0.4 microM with LS; 0.3-1.2 microM with CF) with cytotoxic activities equal to or higher than quinones CG, as reported previously. Incubation of LS or CF with the CG-quinones and mansonones E and F caused the release of H2O2 and O2-. from the whole cells to the suspending medium, as detected by the microperoxidase and adrenochrome assays, respectively. Lower O2-. and H2O2 production values were obtained with perezone and primine, two p-benzoquinones used as controls. Quinones effect on O2-. and H2O2 production was closely related to their concentration and with mansonones E and F, O2-. production was 4-5-fold higher than H2O2 production. Smaller differences were observed with the CG-quinones. Peroxide production in the assayed organisms was the result of quinone redox-cycling, which involved an anaerobic, reductive phase producing quinols, and an aerobic phase (II), in which quinol oxidation and peroxide production (O2-., H2O2) occurred. With mansonones E and F, and quinone CG, phase II rate was faster than or similar to phase I rate, but with mansonones A and C, the quinols oxidation rate was 8-10-fold slower than the quinones reduction rate. These differences fit in well with a) the quinol oxidation rates, measured in vitro; b) O2-. production by quinols oxidation and c) quinols capability for producing lucigenin chemiluminescence. These results support the assumption that oxyradicals play a relevant role in o-naphthoquinones cytotoxic action, despite the presence of catalase and other protective enzymes in CF and LS. Other effects are not, however, ruled out. CF and LS sensitivity towards the assayed o-quinones was similar or higher than that of Trypanosoma cruzi, thus allowing the use of those organisms for preliminary screening of antichagasic drugs.

Animals↗
PubMed1977

[Interrelationship between the generation of oxygen anion-radicals and the reduction of artificial acceptors and cytochrome P-450 by NADPH-cytochrome c reductase].

The interaction of NADPH-cytochrome c reductase with oxygen, artificial acceptors and cytochrome P-450 is investigated. It is found that generation of oxygen anion-radicals (O2-), determined from the reaction of adrenaline oxidation into adrenochrome, proceeds independently on the reactions of interaction with artificial "anaerobic" acceptors-cytochrome c, dichlorophenolindophenol. Propylgallate competitively inhibits the reaction of adrenaline oxidation by isolated DADPH-cytochrome c reductase and non-competitively suppress the reaction of cytochrome c reduction. In contrast to the process of electron transfer on cytochrome c, there is a direct correlation between the rate of cytochrome P-450 reduction and the rate of adrenaline oxidation in liver microsomes. Hexobarbital increases V of the adrenaline oxidation reaction and does not affect the Km value, while metirapon, a metabolic inhibitor, decreases the Vmax and does not change Km. On the basis of the data obtained it is suggested that the reactions of NADPH-cytochrome c reductase interaction with oxygen and artificial "anaerobic" acceptors are connected with different redox-states of flavoprotein or with different flavine coenzymes, and that the electron transport on cytochrome P-450 and directly on oxygen takes place in interrelated redox-states of flavoprotein.

2,6-Dichloroindophenol↗
PubMed1989

Formation of superoxide radical and hydrogen peroxide enhanced by trinitrotoluene in rat liver, brain, kidney, and testicle in vitro and monkey liver in vivo.

Trinitrotoluene (TNT) increased the formation of adrenochrome from adrenaline and the formation of formaldehyde from methanol in rat liver mitochondria and microsomes in vitro as well as in monkey liver mitochondria and microsomes in vivo. The effects were more prominent at higher TNT concentrations. These findings indicate that TNT enhances the production of superoxide radicals (O2) and hydrogen peroxide (H2O2). The production of O2 was more prominent in systems containing added TNT than in those containing added benzyl viologen. H2O2 production by mitochondria was more pronounced in the liver than in other organs, but its production by microsomes was more pronounced in the brain than in other organs. The results suggest that TNT undergoes cycling reduction which produces oxidative stress.

Animals↗
PubMed1989

Source of superoxide anion radical in aerobic mixtures consisting of NAD[P]H, 5-methylphenazinium methyl sulfate and nitroblue tetrazolium chloride.

The source of superoxide anion radical (O2-.) in aerobic mixtures consisting of NAD[P]H, 5-methylphenazinium methyl sulfate (or its 1-methoxy derivative) and tetrazolium salt was investigated using superoxide dismutase (SOD), Mn(II), ferricytochrome-C, and epinephrine as probes. NAD[P]H + phenazine + O2 was found to reduce nitroblue tetrazolium, iodonitrotetrazolium, and thiazolyl blue in a manner sensitive to agents that dismutase O2-., viz., SOD and Mn(II). It also mediated the reduction of ferricytochrome-C, and augmented the autooxidation of epinephrine to the adrenochrome, without a tetrazolium salt present in the medium. The autooxidation of epinephrine, but not the reduction of ferricytochrome-C, was found to be sensitive to SOD. Nitroblue tetrazolium, either singly or in combination with SOD, did not stimulate the reduction of ferricytochrome-C. The oxidation of NADH, mediated by a catalytically low concentration of phenazine(+O2), was augmented two-fold by SOD. These observations are consistent with, and lend support to, a scheme of redox events (Scheme-3) wherein it is proposed that the source of O2-. in the NAD[P]H + phenazine + tetrazolium(+O2) system is the reduced phenazine, that the tetrazoinyl radical (a one-electron reduction product of tetrazolium) may not reduce O2 to O2-., that the redox reaction between semiquinone radicals of phenazine and O2 is reversible, and that the disproportionation of semiquinone radicals constitutes an important rate-limiting reaction in the expression of phenazine redox couple.

Aerobiosis↗
PubMedDate not supplied

[Effect of naphthoquinone-imines on the production of hydrogen peroxide by Crithidia fasciculata and Leptomonas seymouri].

It has been synthesized a series of 4-aminoisoxazol-1,2-naftoquinones, which inhibit growth and DNA synthesis in Trypanosoma cruzi. This effect was related to quinone induction of oxyradical generation. N-(5-methyl-3-isoxazolyl)-4-amino-1,2-naftoquinone and 2-hydroxy-N-(3,5-dimethyl-1-4-isoxazolyl)-1,4-naftoquinone-4 -imine inhibited also growth of Crithidia fasciculata and Leptomonas symouri, two organisms that may prove useful for the assay of trypanocidal drugs. In order to establish the role of oxyradicals for quinone-imine toxicity, the latter redox-cycling was demonstrated by a) reversible change in their spectra; b) reduction under anaerobic conditions, and c) quinol oxidation by oxygen. Production of H2O2, measured by the microperoxidase method, was maximal with N-(5-methyl-3-isoxazolyl)-4-amine-1,2-naftoquinone (IVD) (0.29-0.26 nmol/min/mg of cell protein), either with C. fasciculata or L. seymouri. Lesser, though significant activities were obtained with 2-hydroxy-N-(5-methyl-3-isoxazolyl)-1,4-naftoquinone-4-imine (IIID) and 2-hydroxy-N-(3-methyl-5-isoxazolyl)-1,4-naftoquinone-4-imine (IIIE) whereas IIIA and IIIC were inactive. O2-. generation, measured by the adrenochrome method, was induced by naftoquinone-imines with a hydroxyl group at C-2 (IIIE, 2-hydroxy-N-(3,5-dimethyl-4-isoxazolyl)-1,4-naftoquinone-4-i mine (IIIC) and 2-hydroxy-N-(3,4-dimethyl-5-isoxazolyl)-1,4-naftoquinone-4-i mine (IIIA), but no by IVD, with a carbonyl group at C-2. Measurement of catalase and superoxide dismutase in both organisms yielded significant activities, but ascorbate peroxidase, guaiacol peroxidase and bencidine peroxidase were inactive.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Two sites of azo reduction in the monooxygenase system.

The mechanism of the azo reduction of sulfonazo III and amaranth by the rat hepatic monooxygenase system was studied. Air strongly inhibited (greater than 95%) the enzymatic reduction of both azo compounds; a 100% CO atmosphere inhibited amaranth reduction (greater than 90%) but only slightly inhibited sulfonazo III reduction (13%). The addition of 50 microM sulfonazo III to microsomal incubations stimulated oxygen consumption, NADPH oxidation, and adrenochrome formation, whereas 100 microM amaranth did not. The reduction potentials of these two azo compounds were also very different (amaranth, E = -0.620 V; sulfonazo III, E = -0.265 V versus normal hydrogen electrode). The organic mercurial mersalyl converted cytochrome P-450 to cytochrome P-420 (68%) and markedly decreased NADPH-cytochrome P-450(c) reductase activity (97%) in microsomal preparations, presumably by inactivating or destroying functional sulfhydryl groups important for the catalytic activity of these enzymes. GSH was used to restore, and NADP+ to protect, the activities of the monooxygenase components from the effects of mersalyl. The data indicate that inactivation of NADPH-cytochrome P-450(c) reductase inhibits sulfonazo III and amaranth reduction, whereas inactivation of cytochrome P-450 inhibits only amaranth reduction. Furthermore, the reduction of sulfonazo III by purified microsomal NADPH-cytochrome P-450(c) reductase was significantly faster than the rate of reduction of amaranth. These studies demonstrate that two distinct sites of azo reduction exist in the monooxygenase system and that not all azo compounds are reduced by cytochrome P-450.

Amaranth Dye↗
PubMedDate not supplied

[Growth and DNA synthesis inhibition and superoxide anion formation by iminoquinones in Trypanosoma cruzi].

Despite its epidemiological importance, chemotherapy of Chagas' disease is still an unsolved problem. Many drugs have been assayed for their trypanocidal action on T. cruzi, but, so far, naftoquinone-imines have not been included in drug screenings. Fernández A.E. et al., prepared a series of 4-(aminomethylisoxazolyl)-1,2-naftoquinones. Some of these, namely, IIIA (2-hydroxy-N-(3,4-dimethyl-5-isoxazolyl)-1,4-naftoquinone-4- imine), IIIC hydroxy-N-3,5-dimethyl-4-isoxazolyl)-1,4-naftoquinone-4-i min e, IIIE (2-hydroxy-N-(3-methyl-5-isoxazolyl)-1,4-naftoquinone-4-i min e), and IVD (5-methyl-3-isoxazolyl)-1,2-naftoquinone-4-imine) were assayed on T. cruzi epimastigotes. Parasite growth and DNA synthesis were inhibited 12-36% and 14-49%, respectively, by 18-19 microM quinones or 44-83% and 37-73%, respectively, by 60-78 microM quinones (Table 1). The assayed compounds (37-100 microM concentration) stimulated oxygen uptake (Figs. 2 and 3) and superoxide anion generation by epimastigotes to 0.20-0.70 nmol/min/mg of cell protein (O2- measured by the adrenochrome method, Table 2). In the presence of quinones, T. cruzi mitochondrial fraction supplemented with 0.42 mM NADH produced O2- at a rate of 1.10-1.45 nmol/min/mg of protein (31 and 75 microM quinone, respectively; Table 3) whereas, under the same experimental conditions, the microsomal fraction supplemented with NADPH produced O2- at rate of 0.85 and 1.03, respectively (same units). The kinetics of O2- generation by the mitochondrial fraction supplemented with quinone IIIC and NADH revealed two interacting sites (Fig. 5). The corresponding Km(s) were 5.2 and 17 microM and the Vm, 13 and 17 nmoles O2-/min/mg of protein, respectively. The quinone interaction with the mitochondrial membranes involved a "quinone reductase" located on the substrate site of the antimycin site, as shown by the 3.6-fold increase of the oxygen uptake rate induced by quinone IIIE in Fig. 2. Apparently, the quinone excess inhibited the reductase since by varying the quinone concentration in the 0-500 microM range, the oxygen uptake versus quinone concentration plots showed a maximum at 100-150 microM quinone (Fig. 3). O2- generation by quinones depended on the latter redox-cycling, as shown by a) the decrease of quinone absorption at 480-500 nm after incubation with T. cruzi epimastigotes for the time necessary to exhaust the reaction mixture oxygen, and b) the reappearance of the quinone absorption band after oxygenation of the anaerobic reaction mixture (Fig. 6).

Animals↗
PubMedDate not supplied

[Effect of ionizing radiation on O2 generation by cytochrome P-450].

A study was made of generation of superoxide anion-radical (O2-) by cytochrome P-450 in a microsomal membrane of rat liver. Using spectrophotometry (by oxidation of adrenaline to adrenochrome) and ESR (with a spin-trap, tiron) the authors showed the ability of O2- generation by P-450 through decomposition of organic peroxides. During the first 24 h following irradiation of rats with doses of 7 and 10 Gy, the generation of O2- by cytochrome P-450 of rat liver microsomes was increased. Mechanisms of the postirradiation modification of O2- generation rate are discussed.

1,2-Dihydroxybenzene-3,5-Disulfonic Acid Disodium ↗
PubMed1986

[Kinetic study of the oxidase reaction of ceruloplasmin].

The effects of ionic strength, buffer composition and pH on the oxidase activity of ceruloplasmin isolated from human donor blood were studied. The steady-state kinetics of ceruloplasmin-catalyzed oxidation of organic substrates (pyrocatechine, adrenaline, rho-phenyldiamine) and Fe(II) was analyzed. The relationship between the initial reaction rate and Fe(II) concentration is described by the Michaelis--Menten kinetics, that for organic substrates--by substrate activation or by a scheme which implicates the existence of two catalytic centers in the enzyme molecule. The inhibition of adrenaline oxidation by its reaction product, adrenochrome, is competitive. The reactions studied were shown to occur via the formation of a ternary complex.

Catalysis↗
PubMed1983

A role for glutathione disulfide as a scavenger of oxygen radicals produced by 2,3-dichloro-1,4-naphthoquinone.

The addition of 2,3-dichloro-1,4-naphthoquinone (CNQ) to isolated mitochondria supplemented with GSSG resulted in a respiratory burst with the production of O2- and H2O2, and a decrease in the level of measurable disulfide. Superoxide generated by the xanthine oxidase system or by CNQ-treated mitochondria caused the reduction of GSSG to GSH. Both disulfide reductions were partially sensitive to exogeneous SOD. GSSG was also shown to interfere with the epinephrine - adrenochrome superoxide assay system. The findings reported herein support the conclusion that GSSG is capable of scavenging O2- and has the potential to scavenge other free radicals by a similar mechanism.

Animals↗
PubMed1984

Electron spin resonance-spin stabilization of semiquinones produced during oxidation of epinephrine and its analogues.

The ESR-spin stabilization approach has been employed to detect and characterize o-semiquinone radicals from the oxidation of epinephrine and related materials (norepinephrine, 3,4-dihydroxynorephedrine, isoproterenol, and adrenalone) in aqueous solutions. Semiquinones were generated by various oxidative procedures--enzymatic oxidation (with horseradish peroxidase/H2O2), chemical oxidation (with Ag2O) and photooxidation--and subsequently kinetically stabilized through complexation with Zn2+ ions. This "spin stabilization" affords high radical concentrations, which has allowed unambiguous identification of the radical intermediates. Where appropriate, spectral assignments have been supported by deuterium substitution experiments and computer simulations of spectra. Two types of free radical have been identified: primary "open chain" semiquinones, formed by one-electron oxidation of the parent catecholamines, and secondary semiquinones, formed subsequent to cyclization reactions. The mechanism of formation of the secondary radicals is discussed, and it is concluded that they are derived from product aminochromes. Thus, oxidation of adrenochrome gives a radical identical to the secondary species observed from oxidation of epinephrine.

Catecholamines↗
PubMed1983

The inhibition of peroxyradical-induced chemiluminescence by melanins.

Model melanins synthesized from adrenochrome, DOPA and pyrocatechol quench the peroxyradical-coupled chemiluminescence initiated by electrolysis, photolysis and redox reactions in several selected systems. Calculations of the selfadsorption (inner filter effect) of melanins that decreases chemiluminescence intensity as well as changes in absorption spectra of photolabile substrate-probes such as cytochrome c and rhodamine, lead to the conclusion that melanins scavenge peroxyradicals and inhibit chemiluminescence. The inhibition effect (beta-value) is much higher than that of most powerful antioxidants in all chemiluminescence systems excluding the luminol-hydrogen peroxide one. Donor-acceptor properties of melanins, pertinent to their antioxidizing activity, are discussed.

Antioxidants↗
PubMed1982

Spectrophotometric and titrimetric determination of certain adrenergic drugs, using organic brominating agents.

New oxidimetric titrants, bromamine T, dibromohydantoin, N-bromophthalimide, and N-bromosuccinimide, were applied to the determination of ephedrine.HCl, norephedrine.HCl, and methyldopa. Direct potentiometric and visual indicator titration methods as well as back-titration procedures have been developed for their determination. Oxidation of ephedrine and norephedrine produces benzaldehyde, which is extracted from pH 11.0 phosphate buffer with ether or hexane and determined spectrophotometrically at 242 nm. Beer's law is obeyed in the concentration range from 0.2 to 2 mg ephedrine.HCl and from 0.15 to 1.9 mg norephedrine.HCl. Methyldopa is determined titrimetrically and spectrophotometrically. In addition, this drug acts as a self-indicator: Solutions change from colorless to red, which gradually disappears with continuous addition of brominating agent and shaking. Phosphate buffer is used to produce adrenochrome, characterized by its pink color which can be measured at 485 nm in a working range from 40 to 650 micrograms.

Bromine↗
PubMed1982

Photooxidation of epinephrine sensitized by methylene blue as an assay for the evaluation of alpha-mercaptopropionylglycine as a free radical scavenger.

Free radicals, which are instable intermediates of some biochemical reactions, are produced everywhere in the living matter. They may induce cell membrane lipid peroxidation, with non reversible letal effects. Alpha-mercaptopropionylglycine capability of scavenging free radicals has been tested. H2O2 has been used as a free radical donor under actinic light, epinephrine oxidation to adrenochrome as a revealing system and methylene blue as sensitizing agent. alpha-MPG at 6 mM concentration showed the maximal inhibition of free radical formation in our system. Higher concentrations were unable to produce further inhibition.

Amino Acids, Sulfur↗
PubMed1993

Preliminary study of the relationship between plasma and erythrocyte magnesium variations and some circulating pro-oxidant and antioxidant indices in a standardized physical effort.

The aim of this preliminary study was to determine the relationship between exercise, magnesium (Mg) status, oxidative stress, and antioxidant defence systems. Some corresponding indices have been evaluated: plasma Mg, ascorbate, uric acid, adrenaline, creatine kinase (CK), thiobarbiturate reactive substances, adrenochrome; and in erythrocytes (RBC): reduced and oxidized glutathione (GSH and GSSG) and Mg. Venous blood samples were withdrawn before and 3 min after completion of a 40 min run. Only two significant changes were observed after effort: plasma Mg decreased (P < 0.009) and plasma adrenaline increased (P < 0.005). There was a non-significant tendency for indices of oxidative stress and antioxidant capacity to increase. The significant correlations between plasma Mg and CK (r = -0.88) and between RBC Mg and plasma ascorbate (r = -0.76) disappeared after the effort. Further research is necessary, with a larger number of subjects and variables, to obtain a better understanding of these interactions.

Adult↗
PubMed1976

A 'black cornea' secondary to topical epinephrine.

We report a case of 'black cornea" secondary to topical epinephrine therapy and present the biochemical analysis of the lesion. The formed pigment is a melanin and not the intermediate substance, adrenochrome, as has been previously reported. The pathogenesis of melanin deposition is reviewed and a hypothesis of epinephrine-melanin binding is suggested.

Cornea↗