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PubMed1995

Radiosyntheses of labeled beta-pseudothymidine ([C-11]- and [H-3]methyl) and its biodistribution and metabolism in normal and tumored mice.

In order to develop labeled probes for measuring DNA synthetic rates in vivo we investigated [H-3]- and [C-11]methyl labeled beta-pseudothymidine (2a), and report on their radiosyntheses from methyl iodide. We find methylation is rapid and regioselective on N-1 of the acylurea moiety of 2'-deoxy-beta-D-pseudouridine (1a), in the presence of N,N-diisopropylethylamine and N,N-dimethylformamide at 60 degrees C. Although yields are low (11% [C-11]-decay corrected and 4.4% [H-3]), the method is simple and high specific activity tritiated methyl iodide can be used. In contrast to the rapid degradative de-glycosylation of thymidine in blood, beta-pseudothymidine is stable. However, based on biodistribution and metabolite studies, the anticipated uptake of [H-3]methyl-beta-pseudothymidine into mouse DNA of proliferating tissues (e.g. spleen, thymus and duodenum) and implanted tumors was not observed.

Animals↗

PubMed1992

Photobleaching of 1,3-diphenylisobenzofuran by novel phthalocyanine dye derivatives.

As part of a wider programme to identify novel photosensitizers for photodynamic therapy, the ability of a number of phthalocyanine dyes, including some novel copper phthalocyanine derivatives with a range of water solubilities, to produce potentially cytotoxic species in solution was examined. The experiments were performed in dimethylformamide using 1,3-diphenylisobenzofuran (DPIBF) as the scavenger. The study revealed that all the dyes tested produced DPIBF photobleaching on illumination in vitro, but with widely different (greater than 12x) rates. The possible correlation of DPIBF photobleaching rates with a number of the dyes' properties is discussed.

Benzofurans↗

PubMed1993

Liposome-delivered Zn(II)-2,3-naphthalocyanines as potential sensitizers for PDT: synthesis, photochemical, pharmacokinetic and phototherapeutic studies.

The aim of this investigation is to report the synthesis and fundamental photochemical properties of naphthalocyanines with potential interest for photodynamic therapy (PDT), as well as their pharmacokinetics and phototherapeutic effects in a tumor model. Four zinc naphthalocyanines (ZnNc), unsubstituted ZnNc 1, tetraacetylamido-substituted ZnNc 2, tetraamino-substituted ZnNc 3 and tetramethoxy-substituted ZnNc 4 absorbing around 760-770 nm, were synthesized. The dye-sensitized photo-oxidation of 1,3-diphenylisobenzofuran via 1O2 was studied in dimethylsulfoxide (DMSO). Quantum yields for this photoreaction are 0.135-0.164 and are relatively independent of the kind of substituent. In addition, the photoinduced electron transfer studied in N,N-dimethylformamide-water in the presence of methylviologen and mercaptoethanol is only slightly influenced by the kind of substituent. The pharmacokinetic properties of ZnNc 1 in hamsters bearing a transplanted rhabdomyosarcoma were studied using dipalmitoylphosphatidylcholine liposomes. Experimental PDT of rhabdomyosarcoma was carried out using liposome-delivered ZnNc 1-4. The phototherapeutic effect was evaluated by tumor photonecrosis, the mean tumor diameter during the observation period and the percentage of cured animals. The best effect was found after PDT with ZnNc 2 (50% of the treated animals were cured). A slightly lower effect was observed after application of ZnNc 4 (40% cured animals). No effect at all was noted after PDT with ZnNc 3 and a very low efficiency was found after treatment with ZnNc 1 as photosensitizer. Obviously, the photodynamic effect depends on the biological characteristics as well as on the nature of the substituents.

Animals↗

PubMed2005

Acute and chronic effects of carrier solvents in aquatic organisms: a critical review.

Recognising the scientific and regulatory need for testing relatively hydrophobic or 'difficult substances', the OECD currently recommends that selected organic solvents may be used in aquatic toxicity testing in order to help achieve more effective dispersion of the toxicant. The OECD recommends a maximum solvent concentration of 100 microl l(-1) (with specific gravity equivalents to 100 microl l(-1) in parentheses) for acetone (79 mg l(-1)), dimethylformamide (95 mg l(-1)), dimethylsulfoxide (1.10 mg l(-1)), ethanol (78.9 mg l(-1)), methanol (79.2 mg l(-1)) and triethylene glycol (1.12 mg l(-1)). While this recommendation is supported by historical data, we have recently observed evidence that some solvents may affect the reproduction of certain fish species, and also impact biomarkers of endocrine disruption. This review presents available data on the effects of solvents in aquatic organisms, supplemented by relevant information from mammalian studies (e.g. effects on liver enzyme induction potentially altering the metabolism of sex hormones). In conclusion, it is recommended that maximum effort should be given to avoiding the use of carrier solvents wherever possible, for example through the use of saturation columns or other physical methods (e.g. stirring or ultrasonification). Where solvent use is necessary, however, it is recommended that in reproduction studies with aquatic organisms, the maximum solvent concentration should not exceed 20 microl l(-1) of dilution water.

Amphibians↗

PubMed2004

Direct electrochemistry and electrocatalysis of heme-proteins entrapped in agarose hydrogel films.

Three heme-proteins, including myoglobin (Mb), hemoglobin (Hb) and horseradish peroxidase (HRP), were immobilized on edge-plane pyrolytic graphite (EPG) electrodes by agarose hydrogel. The proteins entrapped in the agarose film undergo fast direct electron transfer reactions, corresponding to FeIII = e- --> FeII. The formal potential (E degrees'), the apparent coverage (Gamma), the electron transfer coefficient (alpha) and the apparent electron transfer rate constant (ks) were calculated by integrating cyclic voltammograms or performing nonlinear regression analysis of square wave voltammetric (SWV) experimental data. The E degrees's are linearly dependent on solution pH (redox Bohr effect), indicating that the electron transfer was proton-coupled. Ultraviolet visible (UV-Vis) and reflection-absorption infrared (RAIR) spectra suggest that the conformation of proteins in the agarose film are little different from that proteins alone, and the conformation changes reversibly in the range of pH 3.0-10.0. Atomic force microscopy (AFM) images of the agarose film indicate a stable and crystal-like structure formed possibly due to the synergistic interaction of hydrogen bonding between N,N-dimethylformamide (DMF), agarose hydrogel and heme-proteins. This suggests a strong interaction between the heme-proteins and the agarose hydrogel. DMF plays an important role in immobilizing proteins and enhancing electron transfer between proteins and electrodes. The mechanisms for catalytic reduction of hydrogen peroxide and nitric oxide (NO) by proteins entrapped in agarose hydrogel were also explored.

Absorption↗

PubMed2005

Benzene analysis in workplace air using an FIA-based bacterial biosensor.

A bacterial biosensor based on flow injection analysis (FIA) has been developed for the determination of benzene in workplace air samples. Benzene can be used by the bacteria Pseudomonas putida ML2 as a sole carbon source, and its aerobic degradation can be measured using a dissolved oxygen electrode. The bacterial cells were immobilised between two cellulose acetate membranes and fixed onto a Clark dissolved oxygen probe, which was inserted into a custom-made flow cell. The applicability of the biosensor for the analysis of air samples containing benzene was investigated. Air samples were collected from a controlled exposure room using charcoal adsorption tubes, and benzene extracted with solvent desorption using dimethylformamide (DMF). The biosensor displayed a linear detection range between 0.025 and 0.15 mM benzene based on standard solutions containing a maximum of 2% DMF, with a response time of 6 min. This linear detection range allows the analysis of air containing between 3 and 16 ppm benzene based on a 60-min sampling period. DMF proved to be compatible for use with the biosensor, causing minimal interference with the sensor response and causing no toxic effects on the bacterial cells. The FIA system was easily transported to an in situ location, and a correlation was obtained between the biosensor and gas chromatography (GC) results for the preliminary air samples investigated. Moreover, the biosensor displayed no interference to other benzene related compounds in the BTEX range. The results from this work have shown that the biosensor has potential applications for the analysis of benzene in workplace air samples, with the added advantages over the conventional GC methods of low operation costs, ease of use, and portability for in situ measurements.

Air Pollutants, Occupational↗

PubMed2005

Synthesis, properties, and photodynamic inactivation of Escherichia coli using a cationic and a noncharged Zn(II) pyridyloxyphthalocyanine derivatives.

The photodynamic effect of a cationic Zn(II) N-methylpyridyloxyphthalocyanine (ZnPc 2) and a noncharged Zn(II) pyridyloxyphthalocyanine (ZnPc 1) has been compared in both homogeneous media bearing photooxidizable substrates and in vitro using a typical Gram-negative bacterium Escherichia coli. Absorption and fluorescence spectroscopic studies were analyzed in different media. Fluorescence quantum yields (varphiF) of 0.23 for ZnPc 1 and 0.22 for ZnPc 2 were calculated in N,N-dimethylformamide (DMF). The singlet molecular oxygen, O2(1Deltag), production was evaluated using 9,10-dimethylanthracene (DMA) in DMF yielding values of PhiDelta=0.56 for ZnPc 1 and 0.59 for ZnPc 2. A faster decomposition of L-tryptophan (Trp), which was used as biological substrate model, was obtained using ZnPc 2 as a sensitizer with respect to ZnPc 1. In biological medium, the E. coli cultures were treated with 10 microM of sensitizer for different times at 37 degrees C in the dark. Both ZnPcs 1 and 2 are rapidly bound to E. coli cells in 5 min and the amount of cell-bound sensitizer is not appreciably changed incubating the cultures for longer times. The recovered ZnPc 2 after one washing step is approximately 3 times higher than 1, reaching a value of approximately 3 nmol/10(6) cells. After irradiation with visible light, a higher photoinactivation of cells was found for ZnPc 2. Thus, a approximately 4.5 log (99.997%) decrease of cell survival was obtained after 30 min of irradiation. On the other hand, a very low photodamage was found for cells treated with ZnPc 1 (approximately 0.5 log). Also, these results were established by stopping of growth curves for E. coli. In the structure of ZnPc 2, the cationic centers are isolated from the phthalocyanine ring by an ether bridge, which also provides a higher mobility of the charges facilitating the interaction with the outer membrane of the Gram-negative bacteria. These studies show that cationic ZnPc 2 is an efficient phototherapeutic agent with potential applications in photodynamic inactivation of bacteria.

Anthracenes↗

PubMed2006

Chemo-enzymatic synthesis of 1,4-oxazepanyl sugar as potent inhibitor of chitinase.

N-acetyl glucosamine 1 is selectively converted into 2 without protection of the other hydroxyl groups by allylation of the anomeric alkoxide in N,N-dimethylformamide containing lithium bromide. We use cell density cultures to produce the allylated derivative of penta-N-acetyl-chitopentaose by using 2 as the initial acceptor for the synthesis of 3 in vivo. Upon periodate oxidation, 3 is transferred to 4. Compound 4 is quickly subjected to sodium borohydride reduction and NH3 amination, which afforded the target compound 5. In 5-binding chitinase assay, it indicates that the chitinase is obviously inactivated by 5 with IC50 = 4.7 micromol/L.

Carbohydrate Conformation↗

PubMed2006

Synthesis of 6-chloroisoquinoline-5,8-diones and pyrido[3,4-b]phenazine-5,12-diones and evaluation of their cytotoxicity and DNA topoisomerase II inhibitory activity.

The substituted chloroisoquinolinediones and pyrido[3,4-b]phenazinediones were synthesized, and the cytotoxic activity and topoisomerase II inhibitory activity of the prepared compounds were evaluated. Chloroisoquinolinediones have been prepared by the reported method employing 6,7-dichloroisoquinoline-5,8-dione. The cyclization to pyrido[3,4-b]phenazinediones was achieved by adding the aqueous sodium azide solution to the dimethylformamide solution of corresponding chloroisoquinoline-5,8-dione. The cytotoxicity of the synthesized compounds was evaluated by a SRB (Sulforhodamine B) assay against various cancer cell lines such as A549 (human lung cancer cell line), SNU-638 (human stomach cancer cell), Col2 (human colon cancer cell line), HT1080 (human fibrosarcoma cell line), and HL-60 (human leukemia cell line). Almost all the synthesized pyrido[3,4-b]phenazinediones showed greater cytotoxic potential than ellipticine (IC(50)=1.82-5.97 microM). In general, the cytotoxicity of the pyrido[3,4-b]phenazinediones was higher than that of the corresponding chloroisoquinolinediones. The caco-2 cell permeability of selected compounds was 0.62 x 10(-6)-35.3 x 10(-6)cm/s. The difference in cytotoxic activity among tested compounds was correlated with the difference in permeability to some degree. To further investigate the cytotoxic mechanism, the topoisomerase II inhibitory activity of the synthesized compounds was estimated by a plasmid cleavage assay. Most of compounds showed the topoisomerase II inhibitory activity (28-100%) at 200 microM. IC(50) values for the most active compound 6a were 0.082 microM. However, the compounds were inactive for DNA relaxation by topoisomerase I at 200 microM.

Caco-2 Cells↗

PubMed2006

Synthesis and antitumor activity of indolylpyrimidines: marine natural product meridianin D analogues.

Marine indole alkaloid meridianin D analogues have been synthesized starting from the appropriate 3-cyanoacetyl indole. A facile two-step conversion of 3-cyanoacetyl indole to the corresponding cyano meridianin D analogue by treatment with dimethylformamide-dimethylacetal and further cyclization of the resulting enaminonitrile with aminoguanidine is described. Then, alkaline hydrolysis of cyano meridianin D afforded the carboxylic acid analogue. The treatment of acid with 75% H(2)SO(4) afforded the desired 6-debromomeridianin D. Simply treatment of cyano meridianin D analogue with hydrazine hydrate afforded the amidrazone analogue. The biological evaluation indicated that cyano analogue showed good cytotoxic activity with IC(50) values of 0.85 and 2.65microg (against MCF7 and HeLa, respectively), but acid and amidrazone analogues showed high cytotoxicity with IC(50) values of 0.75 and 0.25microg, respectively (against MCF7).

Animals↗

PubMed2006

Synthesis and efficacy of 1-[bis(4-fluorophenyl)-methyl]piperazine derivatives for acetylcholinesterase inhibition, as a stimulant of central cholinergic neurotransmission in Alzheimer's disease.

The cholinergic hypothesis of Alzheimer's disease (AD) has spurred the development of numerous structural classes of compounds with different pharmacological profile aimed at increasing central cholinergic neurotransmission. Thus proving a symptomatic treatment for this disease are cholinomimetics with the pharmacological profile of acetyl cholinesterase (AchE) inhibitors. The novel bioactive 1-[bis(4-fluorophenyl)-methyl]piperazine derivatives were synthesized under mild conditions using different aryl/alkyl halides and heterocyclic alkyl halides with 1-[bis(4-fluorophenyl)-methyl]piperazine in the presence of powdered potassium carbonate in N,N-dimethylformamide. All the synthesized compounds were characterized by spectroscopic techniques, elemental analysis and were screened for their efficacy as AchE inhibitor. Some derivatives in this class showed good inhibition against AchE as compared to neostigmine as standard.

Acetylcholinesterase↗

PubMed2004

Golgi endomannosidase inhibitor, alpha-D-glucopyranosyl-(1 --> 3)-1-deoxymannojirimycin: a five-step synthesis from maltulose and examples of N-modified derivatives.

Acid-catalysed O-acetylation of D-maltulose furnished the corresponding per-O-acetylated fructopyranose derivative that, after in situ deprotection at O-2 by reaction with triphenylphosphane dibromide, gave open-chain 2,3,4,6-tetra-O-acetyl-alpha-D-glucopyranosyl-(1 --> 4)-1,3,5-tri-O-acetyl-6-bromo-6-deoxy-D-fructose. Standard deprotection employing sodium methoxide in methanol at -30 degrees C, followed by treatment of the resulting free 6-bromodeoxymaltulose with sodium azide in N,N-dimethylformamide, allowed access to 6-azidodeoxymaltulose. Hydrogenation over Pearlman's catalyst, accompanied by intramolecular reductive amination, yielded the desired title compound. This route allows access to preparative quantities and to a range of novel analogues with improved biostability.

1-Deoxynojirimycin↗

PubMed2005

Parallel solid-phase synthesis of mucin-like glycopeptides.

The glycopeptide, Ac-Pro-Thr(alpha-D-GalNAc)-Thr(alpha-D-GalNAc)-Thr(alpha-d-GalNAc)-Pro-Leu-Lys-NH(2) (1), which features three consecutive O-glycosylated Thr residues and mimics a portion of mucin 2, has been prepared by solid-phase synthesis. Seven related, partially glycosylated peptides (2-8) were synthesized as well. This suite of molecules allowed a systematic analysis of synthetic protocols. N(alpha)-(9-Fluorenylmethoxycarbonyl)-O-(3,4,6-tri-O-acetyl-2-azido-2-deoxy-alpha-D-galactopyranosyl)-L-threonine pentafluorophenyl ester [Fmoc-L-Thr(Ac(3)-alpha-D-GalN(3))-OPfp] was used as a building block that coupled efficiently when used in a relatively low molar excess, that is, approximately 1.5 equiv, with N,N-dimethylformamide (DMF) as the solvent. For conversion of the azido group to the N-acetyl function, direct treatment with thioacetic acid was preferred over a two-step procedure involving reduction with dithiothreitol (DTT) followed by N-acetylation. Effective O-deacetylation of 1-8 in solution was achieved by treatment with sodium methoxide (10-15 mM; approximately 5 equiv) in methanol. On-resin deacetylation techniques were also examined, using sodium methoxide (6-10 mM) in DMF-methanol (17:3) (for 4 and 11) or hydrazine (70 mM) in methanol (for 8). The more convenient on-resin technique in DMF-methanol gave yields similar to solution conditions, and promises to be widely useful for solid-phase glycopeptide synthesis. HPLC profiles showed that free glycopeptides elute earlier than the corresponding O-acetylated derivatives, and that retention times vary systematically with the number of sugar moieties. (1)H NMR studies carried out in water showed an increase in conformational organization of glycopeptides with increased density of glycosylation.

Amino Acid Sequence↗

PubMed2003

Evaluation of liquid chromatography column retentivity using macromolecular probes. III. Partition properties of C18 phases traced by polymers.

Application of polymeric probes was proposed for evaluation of partition properties of the high performance liquid chromatographic stationary phases. The approach was tested with selected silica gel C-18 column packings. Polystyrene (PS) and poly(n-butyl methacrylate) (PnBMA) narrow molar mass standards of low polarity were applied to avoid adsorption of macromolecules on silanols and other polar groups present within column packings. Polar eluent components further reduced contingency of silanophilic interactions. The major eluent component was dimethylformamide (DMF), a thermodynamically poor solvent for polymer probes, which strongly promoted enthalpic partition of macromolecules in favor of the C18 bonded phase. Methyl ethyl ketone (MEK) and diethyl malonate (DEM) were also tested as the partition promoting eluent components. With polystyrenes, MEK was rather inefficient as a partition promoter while DEM was similarly active as DMF. A thermodynamically good solvent for polymer probes, viz. tetrahydrofuran (THF) was added to eluent to reduce and control the extent of partition. The differences in elution behavior of column tested indicate their unlike partition properties.

Chromatography, High Pressure Liquid↗

PubMed2003

Association behaviour of lignins and lignin model compounds studied by multidetector size-exclusion chromatography.

SEC elution curves of spruce milled wood lignin (MWL) and guaiacyl lignin polymer models (G-DHPs) in N,N-dimethylformamide (DMF) exhibited a bimodal elution profile. Light scattering measurements indicated that these elution profiles were due to association effects between the molecules. This became apparent from the determination of high molar masses in the range 10(5)-10(8) g/mol. To study this effect, MWL and DHP were fractionated by precipitation in tetrahydrofuran (THF). The THF-insoluble fractions were found to be the fractions corresponding to the apparent high molar mass part of the DMF elution profiles. The THF-soluble fractions proved to be the less-associated fractions, with lower apparent molecular mass. The individual fractions proved to be rather stable in DMF. Accordingly, the bimodal elution profiles of the starting materials were not the result of an equilibrium between associated and molecular dispersed molecules but of different structures exhibiting a specific and stable association pattern. The different fractions were further characterised by SEC in THF after acetylation to determine molar masses in molecular disperse solutions.

Chromatography, Gel↗

PubMed2004

Determination of chlorophyll in plant samples by liquid chromatography using zinc-phthalocyanine as an internal standard.

Chlorophyll analysis at high precision and accuracy is limited by the lack of suitable, commercially available internal standards for HPLC analysis. Here, the commercially available dye zinc-phthalocyanine is presented as a new internal standard to quantify chlorophylls in vegetable foods and to detect chlorophyll degradation products. The technique was applied to chlorophyll analysis of a selection of vegetable foods. Pigments were extracted with N,N-dimethylformamide from the vegetables and purified by solid phase extraction. Chlorophyll a, a', b, b', corresponding pheophytins, and zinc-phthalocyanine were separated by HPLC using a C18 reverse-phase column and fluorescence detection.

Chlorophyll↗

PubMed2004

Nonaqueous capillary electrophoresis using a titania-coated capillary.

In this work, an ordered mesoporous titania film was introduced to coat a capillary by means of the sol-gel technique. Its electroosmotic flow (EOF) property was investigated in a variety of nonaqueous media (methanol, formamide and N,N'-dimethylformamide and mixtures of methanol and acetonitrile). The titania-coated capillary exhibited a distinctive EOF behavior, the direction and magnitude of which were strongly dependent on various parameters such as the solvent composition, apparent pH (pH*) and the electrolytes. The nonaqueous capillary electrophoresis separation of several alkaloids was investigated in the positively charged titania-coated capillary. Comparison of separation between coated and uncoated capillaries under optimal nonaqueous conditions was also carried out.

Alkaloids↗

PubMed2004

Optimization and validation of a gas chromatographic method for analysis of (RS,SR)-diastereoisomeric impurity in formoterol fumarate.

A gas chromatographic method for the determination of formoterol (RS,SR)-diastereoisomer, a process impurity, in formoterol fumarate was optimized and validated. The method involves silylation of formoterol fumarate with N-(trimethylsilyl)imidazole in N,N-dimethylformamide at room temperature in an autosampler vial to produce trimethylsilyl derivatives of the enantiomers prior to GC analysis. The optimized silylation and separation conditions, respectively, produced good yield and resolution of the analytes. The method appears to be convenient and fast, and permits accurate determination of (RS,SR)-diastereoisomer in formoterol fumarate with adequate precision (R.S.D. = 3.0%, n = 9) and sensitivity (DL < 0.01%) when compared with the official liquid chromatographic limit test method of Pharmeuropa. The method was successfully applied to quality control of commercial formoterol fumarate for their (RS,SR)-diastereoisomer contents.

Adrenergic beta-Agonists↗