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At least 703 records · Page 39Linked to original sources
PubMed2004

Total synthesis of petrobactin and its homologues as potential growth stimuli for Marinobacter hydrocarbonoclasticus, an oil-degrading bacteria.

A modular synthesis was developed to access petrobactin, a catechol-containing siderophore isolated from Marinobacter hydrocarbonoclasticus. A range of petrobactin homologues with differing dihydroxybenzamide motifs and in one case an increased number of carbons in the polyamine backbone were also synthesized. As such, these systems represent new isomeric probes to study iron transport properties in M. hydrocarbonoclasticus. The synthesis of petrobactin and its homologues and the first biological study of how these agents influence the growth of Mycobacterhydrocarbonoclasticus are reported. New synthetic methods were developed to overcome issues (imide formation) encountered in earlier syntheses. Both the (1)H and (13)C NMR of petrobactin were consistent with the recently revised structure showing that petrobactin in fact contains a 3,4-dihydroxybenzene motif rather than a 2,3-dihydroxybenzene motif. The preliminary biological studies suggested that using the native petrobactin 1b for M. hydrocarbonoclasticus-specific growth stimulation may be a poor strategy for oil-spill cleanup.

Alteromonadaceae↗
PubMed2006

Ground-state interactions of spermine-substituted naphthalimides with mononucleotides.

Water soluble spermine, spermine-naphthalimide, and pyridinium-substituted 1,8-naphthalimide derivatives have been synthesized as nucleotide-specific binding agents. Both mono- and bifunctionalized spermine compounds were studied. The photophysical properties of each compound were studied by using time-resolved and steady-state fluorescence and absorption spectroscopies. The fluorescence decay of the mononaphthalimides was adequately fit to a single exponential decay, and in all cases, the lifetime (2.4 ns) was independent of the imide substitutent. In the case of the bisnaphthalimide, emission from both the monomer and ground-state dimer forms was observed. The fluorescence quantum yield of the monomer (0.03) was significantly smaller than that of the mononaphthalimides (0.27). The dimer emission was red-shifted relative to that of the monomer. The singlet-state lifetime of the dimer was found to be 20 ns. In all cases, only absorption from the triplet excited state was observed, indicating no evidence of a naphthalimide radical anion from dimer excitation. The ground-state interactions of the naphthalimides with four nucleotides were investigated. Nucleotide selectivity was evaluated by determining their individual binding constants (Keq). The association constants were measured by using absorption, time-resolved fluorescence, and combined time-resolved and steady-state fluorescence. The equilibrium binding constant was largest for association of the spermine-substituted mononaphthalimide with adenosine monophosphate (Keq=550 M-1) or guanosine monophosphate (Keq=440 M-1). The dimer form of the disubstituted spermine also showed binding constants in excess of 200 M-1 with the purine nucleotides. The association constant for binding of the pyridinium-substituted naphthalimide showed little dependence on the structure of the nucleotide.

Imides↗
PubMed2006

Ceric ammonium nitrate promoted oxidation of oxazoles.

The ceric ammonium nitrate promoted oxidations of 4,5-diphenyloxazoles and oxazoles with various substitution patterns have been investigated. This transformation results in the formation of the corresponding imide in good yield and tolerates a wide variety of functional groups and substituents on the oxazole moiety. [reaction: see text].

Cerium↗
PubMed2006

Characterization of a selective and potent antagonist of human P2X(7) receptors, AZ11645373.

BACKGROUND AND PURPOSE: The ATP-gated P2X(7) receptor has been shown to play a role in several inflammatory processes, making it an attractive target for anti-inflammatory drug discovery. We have recently identified a novel set of cyclic imide compounds that inhibited P2X(7) receptor-mediated dye uptake in human macrophage THP-1 cells. In this study the actions and selectivity of one of these compounds, AZ11645373, were characterized. EXPERIMENTAL APPROACH: We measured membrane currents, calcium influx, and YOPRO-1 uptake from HEK cells expressing individual P2X receptors, and YOPRO1 uptake and interleukin-1beta release from THP-1 cells in response to ATP and the ATP analogue benzoylbenzoyl ATP (BzATP). KEY RESULTS: AZ11645373 up to 10 microM, had no agonist or antagonist actions on membrane currents due to P2X receptor activation at human P2X(1), rat P2X(2), human P2X(3), rat P2X(2/3), human P2X(4), or human P2X(5) receptors expressed in HEK cells. AZ11645373 inhibited human P2X(7) receptor responses in HEK cells in a non-surmountable manner with K (B) values ranging from 5 - 20 nM, with mean values not significantly different between assays. K (B) values were not altered by removing extracellular calcium and magnesium. ATP-evoked IL-1beta release from lipopolysaccharide-activated THP-1 cells was inhibited by AZ11645373, IC(50) = 90 nM. AZ11645373 was > 500-fold less effective at inhibiting rat P2X(7) receptor-mediated currents with less than 50% inhibition occurring at 10 microM. CONCLUSIONS AND IMPLICATIONS: AZ11645373 is a highly selective and potent antagonist at human but not rat P2X(7) receptors and will have much practical value in studies of human cells.

Adenosine Triphosphate↗
PubMed1971

Separation and structural analysis of vinyl- and isovinyl-azobilirubin derivatives.

The coupling reaction of bilirubin with the diazonium salts of ethyl anthranilate or of aniline yields two isomeric azopigments. These can be separated by t.l.c. as their methyl esters. The mass spectra of each pair of azopigments are very similar, showing that they are isomers. Proton-magnetic-resonance spectrometric studies show that they differ in the positions of the substituents on the pyrrolenone end ring; in one compound the methyl and vinyl groups are interposed compared with the other compound. These azo compounds were used as reference standards for determination of the site of conjugation in bilirubin monoglucuronide prepared enzymically. Analysis showed that conjugation occurs at the carboxyethyl side chain of both sides of the bilirubin molecule. During the preparation of the ethyl anthranilate reference compounds a series of minor azopigments were isolated by t.l.c. Analysis of the mass spectra of many of these showed that three side reactions can occur: (1) methylation of the imide carbonyl group; (2) addition of methanol or water to the vinyl substituent; (3) transmethylation of the ethoxycarbonyl group.

Alkenes↗
PubMed2000

Ferroceneacetyl naphthalene diimide as a new electrochemical ligand for DNA sensing.

New electrochemically active DNA ligand 1 was synthesized by the connection of ferroceneacetic acid at the terminal amino moieties of two imide substituents of naphthalene diimide. Electrochemical experiments in aqueous solution containing DMSO showed that the selectivity for double stranded DNA of 1 has increased from that of ligand 2 previously reported. The peak current of 1 shifted toward the negative side from that of 2, thereby shortening the time required for gene detection.

DNA↗
PubMed1994

The cytotoxic activity of cyclic imido alkyl ethers, thioethers, sulfoxides, sulfones and related derivatives.

Cyclic imides such as N-substituted alkyl ethers, thioethers, sulfoxides, sulfones and related derivatives were potent agents against human single cell tumors and selected solid tumor growths, eg adenocarcinoma of the colon and glioma. These agents in the L1210 lymphoid leukemia tumor model preferentially inhibited DNA synthesis. The regulatory enzyme sites in the purine pathway were targets of the agents. Other sites of inhibition were DNA polymerase alpha and thymidylate synthetase activities. d(NTP) pool levels were also reduced by the agents over 60 min.

Animals↗
PubMed2004

Mapping molecular conformation and orientation of polyimide surfaces for homeotropic liquid crystal alignment by nonlinear optical spectroscopy.

Surface-specific sum-frequency vibrational spectroscopy and second-harmonic generation were used to study the structures of polyimide (PI) surfaces for homeotropic liquid crystal (LC) alignment and the molecular orientation of LC adsobates on these surfaces. The imide ring was perpendicular to the surface with one of CO bonds protruding out of the surface and the other pointing into the bulk rather than flat on the surface. The ester CO bond in the side chain was sticking out of the surface with a tilt angle of about 45 degrees -55 degrees from the surface normal, indicating that the rigid side chain core was, more or less, along the surface normal. The part of alkyl chain on the top of the side chain followed the orientation of the side chain core and protruded out of the surface with some gauche defects. The cyano biphenyl LC molecules were adsorbed on the PI preferentially with the terminal cyano group facing the PI surface.

Biophysical Phenomena↗
PubMed1988

Nearest neighbor analysis of outer membrane proteins of nontypeable Haemophilus influenzae.

The arrangement of outer membrane proteins on the surface of nontypeable Haemophilus influenzae was investigated with cleavable and noncleavable bis-imidate cross-linking agents. Whole organisms were subjected to cross-linking agents, and oligomers of proteins were detected by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, two-dimensional gel electrophoresis, and immunoblot assay, using monoclonal antibodies to outer membrane proteins. The major outer membrane protein (P2) formed dimers and trimers detected by all three methods. Oligomers of other outer membrane proteins were not detected. These data indicate that P2 exists as a trimer on the outer membrane and suggest that other outer membrane proteins exist as monomers on the outer membrane.

Antibodies, Monoclonal↗
PubMed2006

Stable photoinduced charge separation in nanostructured films containing a 1,4,5,8-naphthalenetetracarboxylic diimide and cytochrome c.

Photoinduced electron transfer between 1,4,5,8-naphthalenetetracarboxylic diimides (NDI) and the redox protein cytochrome c (cyt c) was studied in solution and in spin-coated thin films. The NDI derivatives employed in this study were N,N'-bis(butyl)-1,4,5,8-naphthalenetetracarboxylic diimide (BNDI) and N,N'-bis(2-phosphonoethyl)-1,4,5,8-naphthalenetetracarboxylic diimide (PNDI). Irradiation of the NDI in solution with UV light (365 nm), in the presence of cyt c, resulted in the reduction of the heme iron from the Fe3+ to the Fe2+ state. When PNDI and cyt c were co-deposited by spin-coating on quartz, glass, and silicon substrates, photoactive films were obtained. Exposition of the films to a UV lamp or natural sun light resulted in photoreduction of the protein, generating a stable charge-separated state. Thin films containing segregated layers of BNDI and cyt c were also prepared. Irradiation of these films, however, resulted in protein degradation. The results can be explained through the formation of imide radicals, which transfer an electron to cyt c in the co-deposited films. In the case of segregated films, protein photodegradation suggests the formation of singlet oxygen within the films.

Biophysics↗
PubMed1989

Phase I clinical investigation of amonafide.

Amonafide (benzisoquinolinedione, NSC 308847) is a new synthetic imide antineoplastic agent with DNA intercalative properties that has been evaluated in a phase I clinical trial. The drug was administered as a single intravenous (IV) infusion over 30 to 120 minutes repeated every 28 days. Ninety-five courses of therapy at doses ranging from 18 to 1,104 mg/m2 were administered to 38 patients with refractory solid tumors. Granulocytopenia was dose limiting. Leukopenia was seen in 13 of 31 courses at doses of 690 mg/m2 or greater. Life-threatening granulocytopenia (less than or equal to 250 microliters) was noted in 1/6 patients treated at 800 mg/m2, 1/8 patients treated at 918 mg/m2, and 2/5 patients treated at 1,104 mg/m2. No definite relationship between myelotoxicity and prior treatment status was noted. Rate-of-infusion dependent, nonhematologic toxicities included diaphoresis, flushing, dizziness, and tinnitus, all of which were ameliorated by increasing the duration of drug infusion to 120 minutes. In addition, nausea and vomiting (grades 1 and 2) were seen in 29/56 courses at doses greater than or equal to 519 mg/m2, but were easily controlled by phenothiazine antiemetics. Amonafide plasma and urine concentrations were determined by high-pressure liquid chromatography (HPLC). Plasma concentrations declined biexponetially with a terminal harmonic mean terminal half-life (t 1/2) of 5.5 h. The mean apparent volume of distribution at steady-state and total body clearance were 532 L/m2 and 84 L/h/m2, respectively. Less than 5% of the total dose of amonafide was excreted unchanged in the urine. Antitumor activity has been noted in one patient with non-small-cell lung cancer (one complete response exceeding 29 months duration) and in one patient with prostatic cancer (complete pain relief and improvement in bone scan for 9 months). The recommended dose for phase II trials with this schedule of amonafide is 918 mg/m2 with dose escalation to amonafide is 918 mg/m2 with dose escalation to myelotoxicity.

Adenine↗
PubMed1975

Identification of drugs and other toxic compounds from their ultraviolet spectra. Part II: Ultraviolet absorption properties of thirteen structural groups.

The ultraviolet absorption spectra of 13 different chemical classes of drugs and toxic organic compounds were studied. A classification system has been developed in which compounds with the same conjugated molecular system and auxochrome substituents are grouped together. Each of these groups has characteristic absorption spectra, showing similarities in the number of major bands, position of maximum absorbance, pH effects, and solvent effects. The absorption maxima and molecular absorptivities are tabulated for approximately 100 compounds, and characteristic spectra of each designated group are illustrated. Classes of drugs included in this study are pyridine derivatives, hydrazines, pyridylamine derivatives, variously substituted phenols, barbiturates, ureides, imides, hydantoins, and conjugted ketones (enones).

Amines↗
PubMed1975

Cross-linked hemoglobins as potential plasma protein extenders.

Reaction of hemoglobin solutions with members of a class of diimidate esters leads to the formation of cross-linked intermolecular or intramolecular complexes depending on the relative concentration of hemoglobin and the length of the carbon chain of the imidate esters. The products have a life-span in the circulation of rabbits significantly greater than that of unmodified hemoglobin and it is suggested that they may serve as plasma protein extenders.

Amino Acids↗
PubMed1990

Photoinduced DNA cleavage by naphthalimide hydroperoxide-specific strand scission at -GG- site of DNA.

We have prepared a series of naphthalene hydroperoxides (1-3) which possess hydroperoxy group at gamma-position of imide carbonyl. Upon photoirradiation (greater than 350 nm) hydroperoxides (1-3) decomposed with efficient generation of hydroxyl radical, which was confirmed by esr spin trapping technique using dimethylpyrroline oxide as a spin trapper. All these hydroperoxides induced DNA strand scission upon photoirradiation (greater than 350 nm), especially hydroperoxide 3 cleaved plasmid phi X 174 DNA (Form I) to give nicked (Form II) and linear (Form III) DNA even at 1 microM concentration. Further, it was observed that 3 exclusively cleaved DNA at the 5'-G site of -GG-sequence.

Base Sequence↗
PubMed1980

[Paramagnetic diethyleneimides of urethane phosphoric acids as antitumor agents].

Under study were paramagnetic diethylene imides of urethan phosphoric acids containing three type groups showing carcinostatic activity. There was found small toxicity and a wide spectrum of the antitumor effect of the compounds, also the correlation between the chemical structure and carcinostatic effect was investigated. The nitroxyl radical was shown to participate in the antitumor effect manifestation.

Animals↗