Pharmacophore Reassignment for Induction of the Immunosurveillance Cytokine TRAIL

Tumor necrosis factor (TNF)‐related apoptosis‐inducing ligand (TRAIL) is an immunosurveillance cytokine that kills cancer cells but demonstrates little toxicity against normal cells. While investigating the TRAIL‐inducing imidazolinopyrimidinone TIC10, a misassignment of its active structure was uncovered. Syntheses of the two isomers, corresponding to the published and reassigned structures, are reported. The ability of each to induce TRAIL expression in macrophages was investigated and it was found that only the compound corresponding to the reassigned structure shows the originally reported activity; the compound corresponding to the published structure is inactive. Importantly, this structural reassignment has furnished a previously unknown antitumor pharmacophore.     

Liquid-phase combinatorial synthesis: In search of small-molecule enzyme mimics

Summary The applications, advantages and recent advances in liquid-phase combinatorial chemistry using poly(ethyleneglycol) as a soluble polymer support are reviewed. Our recent efforts towards the synthesis of peptide-based catalysts on polyethyleneglycol are reported. The screening of libraries of peptides for catalysis is discussed.     

Simultaneous detection of a wide variety of commonly abused drugs in a urine screening program using thin-layer identification techniques.

A single-step extraction method and thin-layer identification techniques capable of testing a wide variety of drugs of abuse are presented. These techniques are well suited for large and/or small drug programs involved in urine testing because they provide substantial economic benefits and improve clinical functioning. The drugs are absorbed on a 6 X 6 cm piece of paper loaded with cation-exchange resin and then eluted from the paper at pH 10.1 using ammonium chloride-ammonia buffer. The simultaneous thin-layer detection of sedatives, hypnotics, narcotic analgesics, central nervous system stimulants and miscellaneous drugs is accomplished by spotting the solution of extracted residue on a 20 X 20 cm Gelman pre-coated silica gel glass microfiber sheet (ITLC Type SA). A two-stage solvent system is used in order to obtain a chromatogram with optimum separation of a wide range of drugs. This system can separate methadone and/or cocaine from propoxyphene, methaqualone, methylphenidate, pentazocine, pipradrol, Doxepin, chlorpromazine, phenazocine, naloxone, naltrexone, imipramine and trimeprazine; amphetamine from phenylpropanolamine and dimethyltryptamine; codeine from dextromethorphan; methamphetamine from dimethyltryptamine, etc. Different detection reagents are then applied in succession to different marked areas of the developed chromatogram. This elegant method of extraction and spraying has enabled us to detect morphine base at a sensitivity level of 0.15 mug/ml, amphetamine sulfate at 1.0 mug/ml, methamphetamine hydrochloride at 0.5 mug/ml, phenmetrazine hydrochloride at 0.5 mug/ml, codeine phosphate at 0.5 mug/ml, methadone hydrochloride at 1.0 mug/ml, secobarbital at 0.36 mug/ml and phenobarbital at 0.5 mug/ml in urine. The minimum volume of urine needed to achieve these sensitivities is 20 ml. The cost of analysis per urine specimen using these techniques for concomitant screening of these drugs is less than US$ 1.     

Solid-phase synthesis of oxazolones and other heterocycles via Wang resin-bound diazocarbonyls

The preparation of Wang resin bound α-diazo-β-ketoesters is described. These highly useful intermediates were used for the synthesis of a series of heterocycle libraries, which were obtained from the resin using TFA cleavage. In addition, a novel route for the synthesis of oxazolones using an N-H insertion strategy is disclosed.     

Polymorphism in Br2 clathrate hydrates

The structure and composition of bromine clathrate hydrate has been controversial for more than 170 years due to the large variation of its observed stoichiometries. Several different crystal structures were proposed before 1997 when Udachin et al. (Udachin, K. A.; Enright, G. D.; Ratcliffe, C. I.; Ripmeester, J. A. J. Am. Chem. Soc. 1997, 119, 11481) concluded that Br2 forms only the tetragonal structure (TS-I). We show polymorphism in Br2 clathrate hydrates by identifying two distinct crystal structures through optical microscopy and resonant Raman spectroscopy on single crystals. After growing TS-I crystals from a liquid bromine-water solution, upon dropping the temperature slightly below -7 degrees C, new crystals of cubic morphology form. The new crystals, which have a limited thermal stability range, are assigned to the CS-II structure. The two structures are clearly distinguished by the resonant Raman spectra of the enclathrated Br2, which show long overtone progressions and allow the extraction of accurate vibrational parameters: omega(e) = 321.2 +/- 0.1 cm(-1) and omega(e)x(e) = 0.82 +/- 0.05 cm(-1) in TS-I and omega(e) = 317.5 +/- 0.1 cm(-1) and omega(e)x(e) = 0.70 +/- 0.1 cm(-1) in CS-II. On the basis of structural analysis, the discovery of the CS-II crystals implies stability of a large class of bromine hydrate structures and, therefore, polymorphism.     

Two-dimensional H2O-Cl2 and H2O-Br2 potential surfaces: an ab initio study of ground and valence excited electronic states

All electron ab initio calculations for the interaction of H2O with Cl2 and Br2 are reported for the ground state and the lowest triplet and singlet Pi excited states as a function of both the X-X and O-X bond lengths (X = Cl or Br). For the ground state and lowest triplet state, the calculations are performed with the coupled cluster singles, doubles, and perturbative triple excitation level of correlation using an augmented triple-zeta basis set. For the 1Pi state the multireference average quadratic coupled cluster technique was employed. For several points on the potential, the calculations were repeated with the augmented quadruple-zeta basis set. The ground-state well depths were found to be 917 and 1,183 cm-1 for Cl2 and Br2, respectively, with the triple-zeta basis set, and they increased to 982 and 1,273 cm-1 for the quadruple-zeta basis set. At the geometry of the ground-state minimum, the lowest energy state corresponding to the unperturbed 1Pi states of the halogens increases in energy by 637 and 733 cm-1, respectively, relative to the ground-state dissociation limit of the H2O-X2 complex. Adding the attractive ground-state interaction energy to that of the repulsive excited state predicts a blue-shift, relative to that of the free halogen molecules, of approximately 1,600 cm-1 for H2O-Cl2 and approximately 2,000 cm-1 for H2O-Br2. These vertical blue-shifts for the dimers are greater than the shift of the band maximum upon solvation of either halogen in liquid water.     

Technological advancements for the detection of and protection against biological and chemical warfare agents

There is a growing need for technological advancements to combat agents of chemical and biological warfare, particularly in the context of the deliberate use of a chemical and/or biological warfare agent by a terrorist organization. In this tutorial review, we describe methods that have been developed both for the specific detection of biological and chemical warfare agents in a field setting, as well as potential therapeutic approaches for treating exposure to these toxic species. In particular, nerve agents are described as a typical chemical warfare agent, and the two potent biothreat agents, anthrax and botulinum neurotoxin, are used as illustrative examples of potent weapons for which countermeasures are urgently needed.     

Development of a FRET assay for monitoring of HIV gp41 core disruption

The fusogenic core assembly of human immunodeficiency virus type 1 (HIV-1) fusion protein gp41 is a critical transformation for viral entry. Molecules that are able to intercept this process are of great therapeutic value as HIV-1 fusion inhibitors. In the search for such molecules, assay systems that can be adapted to high-throughput screens are valuable. Given that gp41 fusogenic transformation is characterized by the hexameric association of heptads located at the N and C terminal regions of the protein ectodomain, the corresponding heptad peptides (CHR and NHR), known to form the six-helix bundle core of gp41 fusion active form, are potentially useful in developing a fluorescence resonance energy transfer (FRET) system for identification of HIV fusion inhibitors. We demonstrate that by strategically placing two FRET probes on these two peptides, we are able to monitor the intermolecular co-association by fluorescence quenching between the fluorescence donor and acceptor. The utility of the system is that it should be adaptable to high-throughput screening (HTS) toward peptide or small-molecule HIV fusion inhibitors targeting the gp41 core. Herein, we report the design, synthesis, and development of a N- and C- terminal peptide FRET pair for screening of gp41 six-helix bundle disruption.     

Emission spectroscopy of atmospheric pressure plasmas for bio-medical and environmental applications

The paper demonstrates several ways of use of the UV-vis optical emission spectroscopy of medium resolution for the diagnostics of atmospheric pressure air and nitrogen plasmas relevant to bio-medical and environmental applications. Plasmas generated by DC discharges (streamer corona, transient spark, and glow discharge), AC microdischarges in porous ceramics, and microwave plasma were investigated. Molecular (OH, NO, CN) and atomic (H, O, N) radicals, and other active species, e.g. N₂ (C, B, A), (B), were identified. The composition of the emission spectra gives insight in the ongoing plasma chemistry. Rotational, i.e. gas, and vibrational temperatures were evaluated by fitting experimental with simulated spectra. Streamer corona, transient spark and microdischarges generate cold, strongly non-equilibrium plasmas (300-550 K), glow discharge plasma is hotter, yet non-equilibrium (1900 K), and microwave plasma is very hot and thermal (∼3000-4000 K). Electronic excitation temperature and OH radical concentration were estimated in the glow discharge assuming the chemical equilibrium and Boltzmann distribution (9800 K, 3 × 10¹⁶ cm⁻³). Optical emission also provided the measurement of the active plasma size of the glow discharge, and enabled calculating its electron number density (10¹² cm⁻³).