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At least 613 records · Page 34Linked to original sources
PubMed2002

Biological activity of secondary metabolites produced by a strain of Pseudomonas fluorescens.

Biological activity of secondary metabolites produced by a plant-growth-promoting Pseudomonas fluorescens was evaluated. The strain produced antibiotics phenazine (PHE), 2,4-diacetylphloroglucinol (PHL) and siderophore pyoverdin (PYO) in standard King's B and succinic acid media, respectively. After extraction, PYO was identified by comparing the UV-spectra and moss-green color development after 'diazotized sulfanilic acid' (DSA) spray in TLC. PHE and PHL were identified by comparing standard compounds on TLC and orange-color development immediately after DSA spray. In vitro antibiosis study of the metabolites revealed their antibacterial and antifungal activity against bacterial test organisms Corynebacterium sp., Mycobacterium phlei and M. smegmatis and test fungi Fusarium moniliforme, F. oxysporum, F. semitectum, F. solani and Rhizoctonia solani. A statistically significantly higher plant growth was recorded in siderophore-amended plantlets under gnotobiotic conditions whereas PHE and PHL did not show any plant-growth-promoting activity. These results support the importance of the secondary metabolites produced by the strain P. fluorescens in enhancing plant growth and in controlling fungal and bacterial pathogens.

Anti-Bacterial Agents↗
PubMed1990

Preparative high-performance liquid chromatography of minor products of Streptomyces cinnamonensis.

Analytical and preparative high-performance liquid chromatography of 3 phenazines and furonaphthoquinone derivative on reversed-phase column are described. The mobile phase was methanol and water. The injected amount of the mixture was about 30 mg for a preparative chromatographic run requiring 80 min. Substances were detected directly in the column effluent by UV detection.

Chromatography, High Pressure Liquid↗
PubMed2005

Isolation and taxonomic affiliation of N-heterocyclic aromatic hydrocarbon-transforming bacteria.

The azaarenes (nitrogen-containing heterocyclic aromatic hydrocarbons) are products of incomplete combustion processes and thus are widely distributed with tar and oil products in the environment. Despite their adverse organoleptic, toxic, and carcinogenic characteristics, the biodegradability and fate of multi-ring azaarenes have received little attention. This work demonstrates the presence of genetically diverse azaarene-degrading bacteria in coal tar-contaminated soils. Thirty-eight bacterial strains able to transform the three-ring azaarenes, 5,6- and 7,8-benzoquinoline, phenanthridine, phenazine, or acridine, were isolated. Only seven of these strains grew in liquid medium on the specific azaarene compounds on which they were isolated using plates; and the rest transformed the azaarenes without growth. Taxonomic characterization by 16S ribosomal DNA sequencing revealed that our enrichment technique provided a diversity of 18 different azaarene-transforming bacterial species. Only a few strains were able to mineralize the homocyclic analogue, phenanthrene. Several of the isolates, e.g., Dyadobacter fermentans, Methylopila capsulata, and Agrobacterium tumefaciens, were related to genera relatively unknown with respect to the biodegradation of xenobiotic compounds. These strains can provide further information on the fate of azaarenes in the environment.

Acridines↗
PubMed2001

Cloning and sequencing of a novel human gene which encodes a putative hydroxylase.

Using a conventional two-hybrid technique with MAWD as bait protein, a novel full-length cDNA was isolated and sequenced from a human liver cDNA library. This cDNA consists of 2,575 base pairs and has a predicted open reading frame encoding 255 amino acids. Overall, it is similar to the catalytic enzyme PHZF, catalyzing the hydroxylation of phenazine-1-carboxylic acid to 2-hydroxyphenazine-1-carboxylic acid. Polymerase chain reaction-based mapping with both a monochromosomal hybrid panel and radiation hybrid cell panels placed the gene to human chromosome 10q21.1 near the marker D10S210.

Base Sequence↗
PubMed1991

Methyl viologen as a preferred electron acceptor in metabolic experiments.

Widely used artificial electron acceptors, including dichlorophenol-indophenol, methylene blue, and phenazine ethosulfate, were shown to induce the nonenzymatic decarboxylation of pyruvate. This characteristic rendered these electron acceptors unsuitable for use in metabolic experiments. In contrast, methyl viologen stimulated the pentose phosphate pathway in mouse preimplantation embryos without decarboxylating pyruvate in the process. Furthermore, methyl viologen had no effect on the Embden-Myerhoff pathway and was not overtly toxic to mouse embryos. These features made methyl viologen a preferred artificial electron acceptor for metabolic studies.

Animals↗
PubMed1975

Cytochrome b and photosynthetic sulfur bacteria.

Chromatophores isolated from the purple sulfur bacterium Chromatium and the green sulfur bacterium Chlorobium exhibit absorbance changes in the cytochrome alpha-band region consistent with the presence of a b-type cytochrome. Cytochrome content determined by reduced minus oxidized difference spectra and by heme photochemically active bacteriochlorophyll (reaction-center bacteriochlorophyll). The b-type cytochrome in Chromatium has an alpha-band maximum at 560 nm and a midpoint oxidation-reduction potential of -5 mV at pH 8.0. The b-type cytochrome in Chlorobium has an alpha-band maximum at 564 nm and an apparent midpoint oxidation-reduction potential near -90 mV. Chromatophores isolated from both Chromatium and Chlorobium cells catalyze a photoreduction of cytochrome b that is enhanced in the presence of antimycin A. Antimycin A and 2-n-heptyl-4-hydroxyquinoline-N-oxide inhibit endogenous (but not phenazine methosulfate-mediated) cyclic photophosphorylation in Chromatium chromatophores and non-cyclic electron flow from Na-2S to NADP in Chlorobium chromatophores. These observations suggest that b-type cytochromes may function in electron transport reactions in photosynthetic sulfur bacteria.

Antimycin A↗
PubMed1975

Evidence for energy migration from photosystem I to photosystem II and the effect of magnesium.

1. With Euglena chloroplasts 7722 nm light excites a fluorescence induction pattern, measured at l,u nm, typical of the Photosystem II reduction of Q. 2. Both methylviologen and phenazine methosulfate partially quench this fluorescence rise in the absence of electron transport between Photosystem II and Photosystem I, and in a manner consistent with their known role of stimulating Photosystem I photochemistry. 3. The variable fluorescence excited with 22 nm light is reduced to a greater extent than that excited by 638 nm light upon chlorophyll dilution during division in the dark. 4. These observations are interpreted to indicate that in Euglena chloroplasts light absorbed by Photosystem I is transferred energetically "uphill" to Photosystem II, where it can perform Photosystem II photochemistry. 5. Magnesium ions stimulate the variable fluorescence with both 638 nm and 722 nm light to a similar extent, which argues against the concept of magnesium ion interrupting energy transfer between Photosystem II and Photosystem I.

Chlorophyll↗
PubMed1981

The thermodynamic properties of some commonly used oxidation-reduction mediators, inhibitors and dyes, as determined by polarography.

The oxidation-reduction midpoint potentials (Em) of the following compounds have been measured in the range of pH from 3 to 12 by polarography: methyl viologen; benzyl viologen; 2-hydroxy-1,4-naphthoquinone; 2-hydroxy-1,4-anthraquinone; N,N,N',N',-tetramethyl-p-phenylenediamine; 2,3,5,6-tetramethyl-p-phenylenediamine; phenazine; N-methylphenazonium methosulfate; N-methylphenazonium sulfonate methosulfate; N-ethylphenazonium ethosulfate; pyocyanine; neutral red; safranin; phenol red; chlorophenol red; cresol red; bromocresol purple; 2,5-dibromo-3-methyl-6-isopropylbenzoquinone and 5-n-undecyl-6-hydroxy-4,7-dioxobenzothiazole. Many of these previously assumed to have a simple behavior in this range have proven to be rather more complicated, and several anomalous observations have been reconciled.

Dibromothymoquinone↗
PubMed1983

Effects of redox agents on the Ca2+-activated K+ channel.

The sensitivity to Ca2+ of the Ca2+-dependent K+ channel can be increased by the artificial electron donor system ascorbate + phenazine-methosulphate in a variety of animal cells. In the human erythrocyte the shift from the 'low' to the 'high-affinity' state seems to depend on the reduction of a membrane component accepting 2 electrons and with an standard redox potential (pH 7.5) of about 47 mV. The relevance of this redox modulation under physiological circumstances is unknown at the moment.

Ascorbic Acid↗
PubMed1989

Mutagenicity of the reaction products of carbazole in the presence of nitrogen dioxide and nitrocarbazole.

The mutagenicity of the photochemical reaction products of carbazole in the presence of nitrogen dioxide (NO2) and nitrocarbazole was investigated using a high-pressure mercury lamp (100 W). Samples extracted from the photochemical reaction products of carbazole with NO2 were more mutagenic than those of acridine and phenazine with NO2 for Salmonella typhimurium strain TA98 in the absence of S9 mix with a trend toward detoxification in the presence of the metabolic system. The mutagenicity of the photochemical reaction products of carbazole with NO2 were higher than those of the reaction products of carbazole with a mixture of NO2 and sulfur dioxide (SO2) and no irradiation. Mononitro- and dinitro-carbazole in the samples extracted from the reaction products were analyzed by mass spectrometry. It was suggested that mononitrocarbazole, which seemed to be weakly mutagenic, and dinitrocarbazole were readily formed by the reaction of carbazole with NO2, and that the other high-potency mutagens were formed by the photochemical reaction of carbazole with NO2 with irradiation by light.

Acridines↗
PubMed1993

Micronucleus induction in mouse peripheral blood reticulocytes by 2,7-diaminophenazine and related compounds.

The peripheral blood micronucleus test using acridine orange (AO) supravital staining was performed with phenazine (Pz), 1-aminophenazine (1-APz), 2-aminophenazine (2-APz) and 2,7-diaminophenazine (2,7-DAPz). Male ICR mice and BDF1 mice were treated intraperitoneally once or twice 24 h apart with each chemical. Irrespective of the number of administrations, Pz and 1-APz were not clastogenic in either mouse strain. In the single treatment regime, 2-APz slightly increased micronucleated reticulocytes (MNRETs) 48 h after 200 mg/kg dosing in ICR mice and 72 h after 400 mg/kg dosing in BDF1 mice. The MNRET frequencies were not enhanced after double treatment in either mouse strain. The single treatment with 2,7-DAPz strongly and dose-dependently induced MNRETs in BDF1 mice, and the incidences of MNRETs, which peaked 48 or 72 h after treatment, were much higher than those in ICR mice. In both mouse strains, the frequencies of MNRETs observed after double treatment with 2,7-DAPz were higher than those after single treatment. The MNRET incidence induced 72 h after first 200 mg/kg dosing in BDF1 mice was 2.21%.

Animals↗
PubMed1984

Intracellular parasite killing induced by electron carriers. I. Effect of electron carriers on intracellular Leishmania spp. in macrophages from different genetic backgrounds.

Mouse peritoneal macrophages were infected with Leishmania parasites from different species, then exposed to the electron carriers methylene blue (MB), toluidine blue O (TB), phenazine methosulfate (PMS) and crystal violet (CV). This led to killing of the intracellular parasites with no harm to the macrophages. On a molar basis, the potency of the electron carriers decreased in the following order: CV, TB, MB and PMS. MB and TB were more active against intracellular compared to free parasites, suggesting that the macrophages themselves might play a role in the observed anti-parasite toxicity. Intracellular killing could be achieved by a short pulse (30 min) of electron carrier. No difference could be detected between macrophages from different mouse strains as regards their capacity to kill intracellular parasites upon incubation with electron carriers. When macrophages from the L. major susceptible ('non-healer') BALB/c strain were infected with either L. enriettii (which is nonpathogenic to mice) or L. major, then exposed to an activating, lymphokine-rich supernatant, destruction of only L. enriettii was achieved, whereas L. major survived intracellularly. Incubation with MB, however, led to intracellular destruction of both parasites. Other Leishmania species could also be killed irrespective of the genetic background of the macrophages. These observations suggest that the triggering events in electron carrier- and lymphokine-mediated intracellular parasite killing are different.

Animals↗
PubMed1984

Intracellular parasite killing induced by electron carriers. II. Correlation between parasite killing and the induction of oxidative events in macrophages.

Mouse peritoneal macrophages infected with Leishmania parasites were exposed in vitro to the electron carriers methylene blue (MB), toluidine blue 0 (TB), phenazine methosulfate (PMS) and crystal violet (CV). This led to parasite destruction without harm to the macrophages. The kinetics of intracellular killing depended on both the drug concentration and the duration of exposure; over 80% of the microorganisms were inactivated within 2.5 min of incubation of the parasitized cells with 10(-4) M MB. On a molar basis, the drugs were considerably more active against intracellular compared to free parasites, suggesting that the macrophages themselves play a role in the observed anti-parasite toxicity. Intracellular killing by macrophages exposed to MB, TB and PMS correlated with the stimulation of oxygen uptake and hexose monophosphate shunt activity in the cells. Cytochrome c markedly inhibited MB-induced intracellular parasite destruction as well as completely blocking parasite killing in macrophages activated by lymphokines, pointing to O-2, H2O2 or products derived therefrom as possible mediators of macrophage toxic activity in both instances. Cytochrome c did not protect free parasites from the direct toxicity of the drug, however. Lipopolysaccharide promoted parasite destruction by lymphokine-activated macrophages, but failed to do so for electron carrier-stimulated cells. These observations suggest that intracellular killing induced by electron carriers results from a direct interaction of the drugs with cellular redox systems, leading to the generation of oxygen metabolites toxic for the parasites.

Animals↗
PubMed1989

Effect of artificial electron acceptors on the cytotoxicity of mitomycin C and doxorubicin in human lung tumor cells.

The cytotoxicities of mitomycin C (MMC) and doxorubicin (DOX) have been proposed to depend on intracellular reduction by reduced flavoproteins. We investigated whether MMC- and DOX-induced cytotoxicity could be inhibited by competing for electrons from reduced flavoproteins by the artificial electron acceptors phenazine methosulfate (PMS), menadione (MEN) and methylene blue (MB). In intact SW-1573 human lung tumor cells these compounds proved to be excellent electron acceptors, as judged from their capacity to induce high levels of cyanide-resistant respiration. In addition, PMS, MEN and MB were found to decrease the cytotoxicity of MMC, by 90, 63 and 29%, respectively, at concentrations that were themselves completely nontoxic. In contrast, DOX cytotoxicity was not detectably affected. These results suggest that in SW-1573 cells flavoprotein-mediated bioreduction is required for the cytotoxic effect of MMC, but not for that of DOX.

Carcinoma, Squamous Cell↗
PubMed1989

Drug metabolism components in liver microsomes from Hypostomus punctatus, a Brazilian benthic fish (Cascudo).

1. The major components of hepatic drug biotransformation system were identified in a Brazilian freshwater benthic fish. 2. Cytochrome P-450 difference spectra were obtained adding 0.02 mM phenazine ethosulphate and 2 mM ascorbate to microsomal suspensions. Basal levels of P-450 were high (0.9 nmol/mg of microsomal protein) and were not induced by 3-MC. 3. Microsomal NADPH-cytochrome C reductase activity was determined in presence of 1.3 x 10(-4) M NADPH, 3.3 x 10(-5) M cytochrome C, 1.0 x 10(-4) M EDTA, 66 micrograms of microsomal protein per ml in a 0.3 M Tris-HCl buffer, pH 8.6. Basal levels of NADPH-cytochrome C were 152.7 nmoles/min/mg of microsomal protein.

Animals↗
PubMed2005

Determination of oxidized and reduced nicotinamide adenine dinucleotide in cell monolayers using a single extraction procedure and a spectrophotometric assay.

While many investigations measuring oxidized nicotinamide adenine dinucleotide (NAD+) and reduced nicotinamide adenine dinucleotide (NADH) have been carried out on several mammalian tissues and blood cells, few reports have dealt with monolayers of cultured cells. Here we show a novel method to measure NAD+ and NADH in monolayers of a neuroblastoma cell line. The method was established by modifying a single extraction procedure originally developed for erythrocytes and an enzymatic cycling assay using a dye that absorbs in visible range. The following modifications were made. (i) Addition of 0.05% of a detergent, Triton X-100, to carbonate-bicarbonate extraction buffer enabled us to accurately measure cellular [NADH]/([NAD+]+[NADH]). (ii) Addition of N-ethyldibenzopyrazine ethyl sulfate salt (phenazine ethosulfate) immediately before the incubation suppressed the gradual decline of the sensitivity of the assay. The procedure presented here provides a simple and inexpensive measurement of NAD+ and NADH in cell monolayers.

Animals↗
PubMed2006

Synthesis, characterization, X-ray structure and DNA photocleavage by cis-dichloro bis(diimine) Co(III) complexes.

Complexes of the type [Co(LL)2Cl2]Cl, where LL = N,N'-ethylenediamine (en), 2,2'-bipyridine (bpy), 1,10-phenanthroline (phen), 1,10-phenanthroline-5,6-dione (phendione) and dipyrido[3,2-a:2',3'-c]phenazine (dppz) have been synthesized and characterized by elemental analyses, IR, UV-visible and NMR spectroscopy. Crystal structure of [Co(phendione)2Cl2]Cl x 0.5 HCl x 3.5 H2O has been solved and refined to R = 0.0552. The crystal is monoclinic with space group C2/c; a = 25.730(2) A, b = 12.375(1) A, c = 18.979(2) A, beta = 119.925(1) degrees and Z = 8. The DNA binding characteristics of the complexes, investigated by covalent binding assay, viscosity measurements and competitive binding fluorescence measurements show that the complexes interact with DNA covalently except the complex containing the planar dppz ligand which intercalates within the base pairs of DNA. The complexes containing en, phen and phendione cleave plasmid pBR 322 DNA upon irradiation under aerobic conditions while the complex containing the dppz ligand cleaves DNA upon irradiation under inert atmosphere. Molecular modeling studies show that the minimized structure of [Co(phendione)2Cl2]+, maintained the octahedral structure while binding to the N7 of guanines and the ligand fits into the major groove without disrupting the helical structure of the B-DNA.

2,2'-Dipyridyl↗
PubMed2006

Functional characterization of a novel hydrocarbonoclastic Pseudomonas sp. strain PUP6 with plant-growth-promoting traits and antifungal potential.

A novel hydrocarbonoclastic bacterium was isolated from rice rhizospheric soil using an enrichment culture technique. Detailed taxonomic studies identified the organism, designated strain PUP6, as a member of the genus Pseudomonas. The bacterium grew in minimal medium amended with n-alkane members of hydrocarbons, n-dodecane (C12H26), n-hexadecane (C16H34), n-octadecane (C18H38), n-octacosane (C28H58); and petroleum fractions such as crude oil and lubricating oil when provided as sole carbon and energy source. Degradation of these n-alkane hydrocarbons and oils in minimal salts medium by strain PUP6 was estimated using gas chromatography with a flame ionization detector. In addition to its hydrocarbonoclastic properties, this bacterium exhibits a broad spectrum of fungal antibiosis against various phytopathogenic fungi. An antifungal metabolite produced by strain PUP6 was isolated, characterized and identified as phenazine-1-carboxamide on the basis of nuclear magnetic resonance and mass spectroscopic analyses. Strain PUP6 also produced plant-growth-promoting siderophores, indoleacetic acid (IAA), phosphate solubilizing enzymes, and fungal cell wall degrading enzymes such as protease and chitinase. This study can be considered as the first report on n-alkane hydrocarbon and oil degradation by a rhizosphere soil bacterium that exhibits biofertilizing and biocontrol traits. Due to its innate multiple functional traits beyond its role in degradation of hydrocarbons, strain PUP6 may be used as plant-growth-promoting rhizobacterium and biocontrol agent against phytopathogenic fungi.

Alkanes↗