Rapid and sensitive silver-lipopolysaccharide staining using PhastSystem in fast horizontal polyacrylamide gel electrophoresis

A rapid and sensitive silver-lipopolysaccharide staining method has been developed by using PhastSystem. The total time of the procedure (including time of Phastgel electrophoresis) is within 2 h. It is at least 10 times faster than the previous reported methods and the sensitivity is also increased.     

Synthesis of spiro-fused (C5)-isoxazolino-(C4)-pyrazolones (1-oxa-2,7,8-triazaspiro[4,4]-2,8-dien-6-ones) via 1,3-dipolar cycloaddition and cycloelimination

An efficient and selective method for the synthesis of spiro-fused (C5)-isoxazolino-(C4)-pyrazolones (C) is reported. The process consists of utilizing the Baylis-Hillman reaction-or a quicker, stepwise MAC procedure-to give I followed by 1,3-dipolar cycloaddition and Swern oxidation to give beta-ketoesters H, which were condensed with hydrazine derivatives to provide hydrazones that underwent cycloelimination. These novel spiro-fused (C5)-isoxazolino-(C4)-pyrazolones were confirmed by spectroscopic analysis as well as single-crystal X-ray of 5. We also concluded that all condensations/cycloeliminations, except with hydrazine itself, were more effective with catalysts or higher reaction temperatures. For example, TiCl(4) was an efficient catalyst for hydrazone formation and cycloelimination with methylhydrazine, while phenyl-, benzyl-, and (4-methoxyphenyl)hydrazine reacted effectively without catalyst in refluxing xylene.     

Porphyrins with exocyclic rings. 14. Synthesis of tetraacenaphthoporphyrins, a new family of highly conjugated porphyrins with record-breaking long-wavelength electronic absorptions

The Soret band for porphyrins is usually observed in the near-ultraviolet at approximately 400 nm, and few examples of "nonexpanded" porphyrins with this major absorption band at values above 500 nm have previously been reported in the literature. Ring fusion with aromatic ring systems such as naphthalene, anthracene, or phenanthrene generally only produces minor bathochromic shifts to this diagnostic absorption band. In this paper, the synthesis of a series of tetraacenaphthoporphyrins and their metal chelates is reported. The compact nature of the acenaphthylene ring system allows the introduction of meso substituents using the Lindsey methodology. meso-Tetraphenylporphyrin 10a shows the presence of a Soret band at 556 nm, while p-methoxy and p-nitro substituents in 10f and 10g, respectively, further shift this band to 560 and 570 nm. Addition of TFA produces the corresponding dications with slightly higher wavelength Soret bands at 565, 573, and 588 nm. These values compare to 525 nm for the dication of tetraacenaphthylene 8, which lacks the meso-aryl substituents, indicating that steric crowding and its resulting distortion of the macrocyclic conformation is responsible for a significant albeit minor portion of these shifts. The nickel(II), copper(II), and zinc chelates of 10a produce Soret bands at 528, 545, and 558 nm, respectively, demonstrating that the trend for increasing red shifts in metalloporphyrins across the periodic table is retained for this series. The lead(II) chelate 19d gave an additional "hyper" shift that brought the Soret band to 604 nm. A similar red shift could be achieved by introducing four phenylethynyl substituents at the meso positions, and this highly conjugated porphyrin (20) also showed a Soret band at 604 nm, while the corresponding dication afforded this absorption band at 629 nm. The essentially additive "hyper" shift due to lead chelation brought the Soret band for the related lead(II) complex 22d to 642 nm. These effects are by far the largest ever observed for true porphyrins and demonstrate that the Soret band can be fined tuned to virtually any part of the visible spectrum.     

Determination of four nitroimidazole residues in poultry meat by liquid chromatography-mass spectrometry

A multi-residue liquid chromatography-mass spectrometry (LC-MS) assay method is described for the determination of four nitroimidazoles in poultry muscle. The extraction procedure is based on liquid-liquid extraction with ethyl acetate followed by an evaporation step. A deuterated internal standard is used. The LC separation was made on a C18 bonded silica column with an aqueous formic acid (0.2%) solution-methanol-acetonitrile (81:13:6) mobile phase. Following electrospray ionization, the protonated molecular ion [M+H]+ is obtained for each compound. Monitoring several ions for each nitroimidazole provides the specificity required for confirmatory assay. Validation of the method was performed to estimate linearity, intra-day and inter-day repeatability, accuracy and detection limit. The present method is capable of identifying nitroimidazole residues in muscle at levels below 5 microg/kg.     

Fractional Brownian dynamics in proteins

Correlation functions describing relaxation processes in proteins and other complex molecular systems are known to exhibit a nonexponential decay. The simulation study presented here shows that fractional Brownian dynamics is a good model for the internal dynamics of a lysozyme molecule in solution. We show that both the dynamic structure factor and the associated memory function fit well the corresponding analytical functions calculated from the model. The numerical analysis is based on autoregressive modeling of time series.     

Molecular and crystal structure of 1-methylmorpholinium 6-methyl-4-phenyl-3-cyano-5-ethoxycarbonyl-1,4-dihydro-2-pyridineselenolate

The structure of 1-methylmorpholinium 6-methyl-4-phenyl-3-cyano-5-ethoxycarbonyl-1,4-dihydro-2-pyridineselenolate was studied using x-ray diffraction analysis. It was found that the 1,4-dihydropyridine ring has a boat conformation, and the plane of the pseudoaxial phenyl substituent is perpendicular to the bottom of this boat. In the anion, the C–Se bond length, which is 1.882(2) Å, indicates that the negative charge is formally located on the Se atom. The anions and cations of the salt in the crystal are linked by intermolecular hydrogen bonds.A. N. Nesmeyanov Institute of Heteroorganic Compounds, Russian Academy of Sciences, Moscow 117813, Russia. T. G. Shevchenko Lugansk State Pedagogical Institute, Lugansk 348011, Ukraine. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 785–789, June, 1998.     

Evaluation of an Economical Sunlamp that Emits a Near Solar UV Power Spectrum for Conducting Photoimmunological and Sunscreen Immune Protection Studies

Expense and inconvenience have restricted the use of the filtered xenon are lamp (solar simulator) as a UV source for conducting large-scale animal studies. Because sunscreen immunoprotective levels are significantly affected by the UV power spectrum of the source it is imperative that a solar simulating source be used for accurate measurements of sunscreen protection levels that are relevant to human UV exposures from sunlight. However, relatively inexpensive sunlamps, e. g. the UVA-340, that emit a UV power spectrum similar to that of a solar simulator are available. Unlike FS-type UVB sunlamps, which have a significant amount of effective immunosuppressive nonsolar UV energy at wavelengths below 295 nm, the immunosuppression effectiveness spectrum of UVA-340 sunlamps was nearly identical to that of a solar simulator. The purpose of this study was to evaluate this sunlamp for conducting photoimmunological and sunscreen immune protection studies. Groups of C3H mice were exposed to a range of UVA-340 sunlamp doses (0.25 KJ/m² to 20.0 KJ/m²) to establish a dose-response curve and determine the minimum immune suppression dose (MISD) for induction of local-type suppression of contact hypersensitivity (CH). The MISD, defined as the lowest UV dose given to produce ～50% suppression of the CH response in mice, was determined to be 1.0 kJ/m² for UVA-340 sunlamps. Immune protection tests on four marketed sunscreen lotions (sun protection factors [SPF] 4, 8, 15 and 30) were then conducted with UVA-340 sunlamps using MISD as the endpoint. The immune protection factors for these sunscreens were equivalent to the level of protection predicated by their labeled SPF. These results are similar to those we have previously obtained using a solar simulator. We conclude from these data that the immunosuppressive effects of UVA-340 sunlamps are similar to those of a solar simulator; however, further studies are needed to determine if UVA-340, or similar, sunlamps are a viable alternative to the solar simulator for conducting large-scale animal experiments that require a relevant UV solar spectrum.     

Benzolactams. 4. Reaction of 3',4'- or 4',5'-dialkoxy-substituted 1-(2'-Bromobenzyl)-2-ethoxycarbonyl-1,2,3,4-tetrahydroisoquinolines with alkyllithium. 1,2 and 1,4 additions of alkyllithium to benzolactams

Treatment of 1-(2'-bromo-3',4'-dialkoxybenzyl)-1,2,3, 4-tetrahydroisoquinoline carbamates, 1a,c, with excess alkyllithium gave 8-oxoberbines, 2a,c, which were successively attacked in situ with another molecule of alkyllithium to give 1,2 and/or 1,4 addition products. A primary alkyllithium, such as MeLi or BuLi, gave a 1,2 addition product, 8-methyleneberbine 9a or 8-butylideneberbine 3a. t-BuLi preferred 1,4 addition, followed by elimination of the alkoxy group, to give 9-tert-butyl-8-oxoberbine 6a or 7c. s-BuLi gave a mixture of 1,2 and 1,4 addition products, 1-[2'-(2' '-methylbutyryl)benzyl]-1,2,3,4-tetrahydroisoquinoline 4a and 9-s-butyl-8-oxoberbine 5a. Similar treatments of carbamate 1b having no alkoxy group at its 3' position gave 1,2 addition products, 8-butylideneberbine 3b, 1-[2'-(2' '-methylbutyryl)benzyl]-1,2,3, 4-tetrahydroisoquinoline 4b, and 1-(2'-pivaloylbenzyl)-1,2,3, 4-tetrahydroisoquinoline 6b, in all cases. Reactions of 1a with s-BuMgCl and isoPrMgCl also gave the 1,4 adduct, 5a, and its 9-isoPr analogue, 12a. Treatment of 9a with excess NaBH(4) in AcOH gave (+/-)-coralydine (10b).     

Kinetics of the hydroxylation of N-picryl-4-[4-(dimethylamino)styryl]pyridinium salts by molecular oxygen in acetonitrile

The reactions of N-picryl-4-[4-(dimethylamino)styryl]pyridinium salts with molecular oxygen in the presence of 4-[4-(dimethylamino)styryl]pyridine (DASP) in acetonitrile proceeds with the formation of DASP picrate. The reactions are first-order relative to the salt cation, molecular oxygen, and the catalyst (DASP). L. M. Litvinenko Institute of Physical Organic and Coal Chemistry, National Academy of Sciences of Ukraine, 70 R, Lyuksemburg ul., Donetsk 340114, Ukraine. Translated from Teoreticheskaya i éksperimental'naya Khimiya, Vol. 34, No. 5, pp. 286–289, September–October, 1998.     

Nitropyrazoles

The double Vilsmeier formylation of theC-methyl group in pyrazole derivatives has been shown to occur when a nitro-group is in the adjacent position of the ring. A method for the synthesis ofC-(diformylmethyl)nitropyrazoles based on this reaction has been developed.For the previous communication, see Ref. 1; for Part 2, see Ref.2 Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1273–1276, July, 1993.