Immunoassay testing for barbiturates using alternative matrices in postmortem tissues from cats and dogs.

The barbiturate drug pentobarbital is commonly used by veterinarians for the euthanasia of domestic animals. During the veterinary forensic autopsy, it is sometimes necessary to determine whether the animal was chemically euthanized with pentobarbital. The use of a human immunochromatographic test for barbiturate screening utilizing dog or cat urine has been previously validated; however, the use of alternative matrices for this purpose is yet to be explored when urine is not available. Postmortem heart, liver, spleen, skeletal muscle, blood and/or urine samples from 20 dogs and 26 cats with a reported chemical euthanasia status were processed using two different methods, bead homogenization and sonication, and screened for barbiturates using a human immunochromatographic test. There was 100% agreement of the immunochromatographic test results using the sonication method with the reported euthanasia status of both dogs and cats. Using the bead homogenization method, agreement with the reported euthanasia status was 93.3% and 96.7% for dogs and cats, respectively, due to invalid test results from four dog and two cat samples. A subset of liver samples (10 canine and 10 feline) was analyzed via gas chromatography-mass spectrometry, and there was 100% agreement between the immunochromatographic test results and gas chromatography-mass spectrometry results for both cats and dogs. Overall, our results support the use of a variety of alternative matrices for barbiturate screening in cats and dogs.

Design, synthesis, and preliminary evaluation of a potential synthetic opioid rescue agent.

BACKGROUND: One of the most prominent opioid analgesics in the United States is the high potency agonist fentanyl. It is used in the treatment of acute and chronic pain and as an anesthetic adjuvant. When used inappropriately, however, ingestion of just a few milligrams of fentanyl or other synthetic opioid can cause opioid-induced respiratory depression (OIRD), often leading to death. Currently, the treatment of choice for OIRD is the opioid receptor antagonist naloxone. Recent reports, however, suggest that higher doses or repeated dosing of naloxone (due to recurrence of respiratory depression) may be required to reverse fully fentanyl-induced respiratory depression, rendering this treatment inadequate. To combat this synthetic opioid overdose crisis, this research aims at identifying a novel opioid reversal agent with enhanced efficacy towards fentanyl and other synthetic opioids. METHODS: A series of naltrexone analogues were characterized for their ability to antagonize the effects of fentanyl in vitro utilizing a modified forskolin-induced cAMP accumulation assay. Lead analogue 29 was chosen to undergo further PK studies, followed by in vivo pharmacological analysis to determine its ability to antagonize opioid-induced antinociception in the hot plate assay. RESULTS: A series of potent MOR antagonists were identified, including the highly potent analogue 29 (IC50 = 2.06 nM). Follow-up PK studies revealed 29 to possess near 100% bioavailability following IP administration. Brain concentrations of 29 surpassed plasma concentrations, with an apparent terminal half-life of ~ 80 min in mice. In the hot plate assay, 29 dose-dependently (0.01-0.1 mg/kg; IP) and fully antagonized the antinociception induced by oxycodone (5.6 mg/kg; IP). Furthermore, the dose of 29 that is fully effective in preventing oxycodone-induced antinociception (0.1 mg/kg) was ineffective against locomotor deficits caused by the KOR agonist U50,488. CONCLUSIONS: Methods have been developed that have utility to identify enhanced rescue agents for the treatment of OIRD. Analogue 29, possessing potent MOR antagonist activity in vitro and in vivo, provides a promising lead in our search for an enhanced synthetic opioid rescue agent.

Design, synthesis and biological evaluation of novel scaffold benzo[4,5]imidazo [1,2-a]pyrazin-1-amine: Towards adenosine A2A receptor (A2A AR) antagonist.

Antagonists of adenosine receptor are under exploration as potential drug candidates for treatment of neurological disorders, depression, certain cancers and potentially used as a cancer immunotherapy. Herein, we describe design and synthesis of novel scaffold benzo[4,5]imidazo [1,2-a]pyrazin-1-amine (6) derivatives. All the compounds were evaluated for A2A AR antagonist activity and displayed encouraging results (IC50 9-300 nM) of A2A AR antagonist binding affinity in biochemical assay. Compound 27 exhibits good activity in A2A AR antagonist cAMP functional assay (IC50 31 nM) and further this compound shows T-cell activation at the IL-2 production assay (EC50 165 nM). Molecular docking studies were carried out to rationalize the observed binding affinity of compound 27.

Selective molecular separation of lignin model compounds by reduced graphene oxide membranes from solvent-water mixture.

Selective separation of lignin depolymerization products is key to fractionating and isolating high-value aromatic compounds from the depolymerization process. The primary aim of this study was to synthesis graphene oxide (GO) membranes for selective separations of lignin oligomeric units from polar organic solvent-water media. GO membranes were synthesized on a polymeric substrate by a shear assisted casting of aqueous GO dispersion using a wire-wound rod. Deposited GO was then reduced to different extents by controlled thermal incubation, and the impact on membrane performance was investigated. The extent of reduction of GO was established by extensive characterization with FTIR, XPS, Raman Spectroscopy, XRD, and contact angle measurements. Impressive performance with the rejection of over 70% for the model compound trimer BMP (2,6-bis[(2-hydroxy-5-methyl phenyl) methyl]-4-methylphenol) was achieved compared to only 20% rejection for the dimer GGE (guaiacylglycerol-ß-guaiacylether) with isopropanol-water (90-10% by volume) as a solvent. This corresponds to an encouraging selective separation with selective permeation of dimer (GGE) 3.5 times higher compared to trimer (BMP). rGO membranes exhibited a stable performance over 84 h of operation at a shear rate of 1.1 Pa in a cross-flow mode of operation. Selective separation of GO can be effectively modulated by controlling the O/C ratio by the extent of reduction of GO; indeed, the retention of trimeric compounds increased with increasing GO reduction. The remarkable performance of GO membranes could enable energy-efficient fractionation of lignin oligomeric compounds from polar organic solvents.

Rhodopseudomonas palustris-based conversion of organic acids to hydrogen using plasmonic nanoparticles and near-infrared light.

The simultaneous elimination of organic waste and the production of clean fuels will have an immense impact on both the society and the industrial manufacturing sector. The enhanced understanding of the interface between nanoparticles and photo-responsive bacteria will further advance the knowledge of their interactions with biological systems. Although literature shows the production of gases by photobacteria, herein, we demonstrated the integration of photonics, biology, and nanostructured plasmonic materials for hydrogen production with a lower greenhouse CO2 gas content at quantified light energy intensity and wavelength. Phototrophic purple non-sulfur bacteria were able to generate hydrogen as a byproduct of nitrogen fixation using the energy absorbed from visible and near-IR (NIR) light. This type of biological hydrogen production has suffered from low efficiency of converting light energy into hydrogen in part due to light sources that do not exploit the organisms' capacity for NIR absorption. We used NIR light sources and optically resonant gold-silica core-shell nanoparticles to increase the light utilization of the bacteria to convert waste organic acids such as acetic and maleic acids to hydrogen. The batch growth studies for the small cultures (40 mL) of Rhodopseudomonas palustris demonstrated >2.5-fold increase in hydrogen production when grown under an NIR source (167 ± 18 µmol H2) compared to that for a broad-band light source (60 ± 6 µmol H2) at equal light intensity (130 W m-2). The addition of the mPEG-coated optically resonant gold-silica core-shell nanoparticles in the solution further improved the hydrogen production from 167 ± 18 to 398 ± 108 µmol H2 at 130 W m-2. The average hydrogen production rate with the nanoparticles was 127 ± 35 µmol L-1 h-1 at 130 W m-2.

Multienzyme immobilized polymeric membrane reactor for transformation of lignin model compound.

We have developed a multienzyme functionalized membrane reactor for bioconversion of lignin model compound involving enzymatic catalysis. Layer-by-layer approach was used to immobilize three different enzymes (glucose oxidase, peroxidase and laccase) into pH-responsive membranes. This novel membrane reactor couples the in situ generation of hydrogen peroxide (by glucose oxidase) to oxidative conversion of a lignin model compound, guaiacylglycerol-B-guaiacylether (GGE). Preliminary investigation of the efficacy of these functional membranes towards GGE degradation is demonstrated under convective flow mode. Over 90% of the initial feed could be degraded with the multienzyme immobilized membranes at a residence time of approximately 22 seconds. GGE conversion product analysis revealed formation of oligomeric oxidation products with peroxidase, which might be potential hazard to membrane bioreactors. These oxidation products could be further degraded by laccase enzymes in the multienzymatic membranes explaining the potential of multienzyme membrane reactors. The multienzyme incorporated membrane reactors were active for about a month time of storage at 4 °C, and retention of activity was demonstrated after repetitive use.

Layer-by-Layer-Assembled Laccase Enzyme on Stimuli-Responsive Membranes for Chloro-Organics Degradation.

Functionalized membranes provide versatile platforms for the incorporation of biocatalysts and nanostructured materials for efficient and benign environmental remediation. The existing techniques for remediating chloro-organics in water consist of both physical and chemical means mostly using metal oxide-based catalysts, despite associated environmental concerns. To offer bioinspired remediation as an alternative, we herein demonstrate a layer-by-layer approach to immobilize laccase enzyme onto pH-responsive functionalized membranes for the degradation of chloro-organics in water. The efficacy of these bioinspired membranes toward dechlorination of 2,4,6-trichlorophenol (TCP) is demonstrated under a pressure-driven continuous flow mode (convective flow) for the first time to the best of our knowledge. Over 80% of the initial TCP was degraded at an optimum flow rate under an applied air pressure of about 0.7 bar or lower. This corresponds to degradation of a substantial amount of the initial substrate in only 36 s residence time, whereas it takes hours for degradation in a batch reaction. This, in fact, demonstrates an energy efficient flow-through system with potentially large-scale applications. Comparison of the stability of the enzyme in the solution phase versus immobilized on the membrane phase showed a loss of some 65% of enzyme activity in the solution phase after 22 d, whereas the membrane-bound enzyme lost only a negligible percentage of the activity in a comparable time span. Finally, the membrane was exposed to rigorous cycles of TCP degradation trials to study its reusability. The primary results reveal a loss of only 14% of the initial activity after 4 cycles of use in a period of 25 d, demonstrating its potential to be reused. Regeneration of the functionalized membrane was also validated by dislodging the immobilized enzyme, followed by immobilization of fresh enzyme onto the membrane.

Flavin-sensitized electrode system for oxygen evolution using photo-electrocatalysis.

Fabrication of bio-electrode systems decorated with redox active biomolecules, flavins, is demonstrated. Exploiting the photochemistry and electrochemistry of flavins, we explored the photo-electrochemical activity of flavin-functionalized electrode systems to assess their potential utility for sustainable energy production. As model systems, lumiflavin and flavin adenine dinucleotide were immobilized on carbon electrodes by dropcasting and covalent grafting techniques. Activity of these bio-electrodes towards generation of O2 from H2O in 0.5 M potassium phosphate buffer at pH 7.1 was demonstrated. Irradiation of the electrode system with visible light led to increased activity of the electrodes with a 3-fold enhancement of oxidation of H2O.

Studies of the di-iron(VI) Intermediate in ferrate-dependent oxygen evolution from water.

Molecular oxygen is produced from water via the following reaction of potassium ferrate (K(2)FeO(4)) in acidic solution: 4[H(3)Fe(VI)O(4)](+) + 8H(3)O(+) → 4Fe(3+) + 3O(2) + 18H(2)O. This study focuses upon the mechanism by which the O-O bond is formed. Stopped-flow kinetics at variable acidities in H(2)O and D(2)O are used to complement the analysis of competitive oxygen-18 kinetic isotope effects ((18)O KIEs) upon consumption of natural abundance water. The derived (18)O KIEs provide insights concerning the identity of the transition state. Water attack (WA) and oxo-coupling (OC) transition states were evaluated for various reactions of monomeric and dimeric ferrates using a calibrated density functional theory protocol. Vibrational frequencies from optimized isotopic structures are used here to predict (18)O KIEs for comparison to experimental values determined using an established competitive isotope-fractionation method. The high level of agreement between experimental and theoretic isotope effects points to an intramolecular OC mechanism within a di-iron(VI) intermediate, consistent with the analysis of the reaction kinetics. Alternative mechanisms are excluded based on insurmountably high free energy barriers and disagreement with calculated (18)O KIEs.

Indium(III) catalysed substrate selective hydrothiolation of terminal alkynes.

In(OTf)(3) is reported as the first catalyst having the ability to selectively catalyse both Markovnikov and anti-Markovnikov hydrothiolation of terminal alkynes under identical reaction conditions depending upon the nature of the thiol employed.

Microwave-promoted catalyst- and solvent-free aza-Diels-Alder reaction of aldimines with 6-[2-(dimethylamino)vinyl]-1,3-dimethyluracil.

A microwave-promoted aza-Diels-Alder reaction between 6-[2-(dimethylamino)vinyl]-1,3-dimethyluracil and aldimines has been developed for the construction of dihydropyrido[4,3-d]pyrimidines. Urea is effectively employed as an environmentally benign source of ammonia in the absence of any catalyst or solvent. The key step in the reaction is in situ generation and trapping of the reactive aldimine formed from urea and aldehyde by the diene system of the uracil. The reaction is clean, and excellent yields are obtained in a matter of a few minutes.

Indium catalyzed tandem hydroamination/hydroalkylation of terminal alkynes.

The first direct intermolecular hydroamination/hydroalkylation of terminal alkynes catalyzed by In(OTf)(3) under one-pot conditions leading to the formation of conjugated ketimines in good yields is described.

Unexpected deviation from diene behaviour of uracil amidine: towards synthesis of some pyrido[2,3-d]pyrimidine derivatives.

Condensation products obtained from the treatment of uracil amidine with preformed or in situ generated suitably substituted olefins unexpectedly undergo intramolecular cyclisation during silica gel chromatography to generate pyrido[2,3-d]pyrimidines. Various reaction conditions are studied and the altered nature of the uracil amidine molecule is further explored by reacting it with different suitably substituted alkenes.

N,N-diphenylbenzamide.

In the title compound, C(19)H(15)NO, the neutral molecules are held together in the crystal structure by very weak C-H...O interactions, giving rise to a linear chain-like structure. The structure of the molecule has been optimized using density functional theory at the B3LYP/6-31G(d) level and this is compared with the molecular structure in the solid state. The two structures show significant differences in the relative orientations of the aromatic rings, which is interesting for further supramolecular study. Apart from the crystal structure analysis, powder X-ray diffraction, UV-visible and thermogravimetric analyses of the compound have been carried out.

Study on changes in optical properties of phenylbenzothiazole derivatives on metal ion binding.

The UV-visible and fluorescence properties of hydroxy substituted benzothiazole derivatives change on interactions with zinc(II), cadmium(II) and mercury(II) ions. The binding of 2-(2'-hydroxyphenyl)benzothiazole is specific to zinc(II) over cadmium(II) and mercury(II). Similar type of interactions of zinc(II), cadmium(II) and mercury(II) with 2-(2',3',4'-trihydroxyphenyl)benzothiazole is observed in their UV-visible absorptions, whereas 2-(4'-hydroxyphenyl)benzothiazole shows interactions with mercury(II) over the other two ions.

1-Benzyl-sulfanyl-2-[(2-chloro-phen-yl)diazen-yl]benzene.

The title compound, C(19)H(15)ClN(2)S, a divalent organosulfur compound belonging to the class of ortho-mercaptoazo compounds, is non-ionic in nature. The azo group in the mol-ecule is moved away from the S atom to attain the stable trans-azo configuration. Here the S atom is not electron deficient, so no intra-molecular N⋯S inter-action exists. Due to steric reasons, the mol-ecule is non-planar: the chlorophenyl and benzyl rings are oriented at dihedral angles of 3.21 (8) and 78.18 (5)°, respectively, with respect to the thiophenyl ring. There are no hydrogen bonds and the crystal structure is stabilized by van der Waals inter-actions.

Aromatic N-oxide bridged copper(II) coordination polymers: Synthesis, characterization and magnetic properties.

The complexes [Cu2(o-NO2-C6H4COO)4(PNO)2] (1), [Cu2(C6H5COO)4(2,2'-BPNO)] n (2), [Cu2(C6H5COO)4(4,4'-BPNO)] n (3), [Cu(p-OH-C6H4COO)2(4,4'-BPNO)2·H2O] n (4), (where PNO = pyridine N-oxide, 2,2'-BPNO = 2,2'-bipyridyl-N,N'-dioxide, 4,4'-BPNO = 4,4'-bipyridyl-N,N'-dioxide) are prepared and characterized and their magnetic properties are studied as a function of temperature. Complex 1 is a discrete dinuclear complex while complexes 2-4 are polymeric of which 2 and 3 have paddle wheel repeating units. Magnetic susceptibility measurements from polycrystalline samples of 1-4 revealed strong antiferromagnetic interactions within the {Cu2}4+ paddle wheel units and no discernible interactions between the units. The complex 5, [Cu(NicoNO)2·2H2O] n ·4nH2O, in which the bridging ligand to the adjacent copper(II) ions is nicotinate N-oxide (NicoNO) the transmitted interaction is very weakly antiferromagnetic.

Solvent induced reactivity of 3,5-dimethylpyrazole towards zinc (II) carboxylates.

The reactions of 3,5-dimethylpyrazole with zinc(II)acetate dihydrate and varieties of aromatic carboxylic acids led to formation of mono-nuclear zinc complexes of composition [Zn(HDMP)2(RCO2)2] (R = C6H5, p-CH3-C6H4, p-NO2-C6H4 etc. HDMP = 3,5-dimethylpyrazole) in methanol, whereas the same reactants in dimethylformamide (DMF) gave binuclear 3,5-dimethylpyrazolato bridged zinc carboxylate complexes containing monodentate 3,5-dimethylpyraozole ligands with composition [Zn2(mu-DMP)2(HDMP)2(RCO2)2]. The mononuclear complexes can be converted to the corresponding binuclear complexes by simply dissolving in DMF. The reaction of zinc(II)acetate dihydrate with p-nitrobenzoic acid and 3,5-dimethylpyrazole in different solvents gave solvated mononuclear complexes of the corresponding solvent. All these solvated complexes having the core [Zn(HDMP)2(p-NO2-C6H4CO2)2] contain two structurally independent molecules in the asymmetric unit (Z' = 2).

N-oxides in metal-containing multicomponent molecular complexes.

Syntheses and structures of three-component rare cocrystals of 4-nitrobenzoic acid, aromatic N-oxides, and aqua complexes of manganese and zinc and their transformation to metal complexes as well as coordination polymers are presented.