Discovery of Novel Quinoline-Based Proteasome Inhibitors for Human African Trypanosomiasis (HAT).

Human African Trypanosomiasis (HAT) is a vector-borne disease caused by kinetoplastid parasites of the Trypanosoma genus. The disease proceeds in two stages, with a hemolymphatic blood stage and a meningo-encephalic brain stage. In the latter stage, the parasite causes irreversible damage to the brain leading to sleep cycle disruption and is fatal if untreated. An orally bioavailable treatment is highly desirable. In this study, we present a brain-penetrant, parasite-selective 20S proteasome inhibitor that was rapidly optimized from an HTS singleton hit to drug candidate compound 7 that showed cure in a stage II mouse efficacy model. Here, we describe hit expansion and lead optimization campaign guided by cryo-electron microscopy and an in silico model to predict the brain-to-plasma partition coefficient Kp as an important parameter to prioritize compounds for synthesis. The model combined with in vitro and in vivo experiments allowed us to advance compounds with favorable unbound brain-to-plasma ratios (Kp,uu) to cure a CNS disease such as HAT.

Staphylococcus aureus Pathogenicity in Cystic Fibrosis Patients-Results from an Observational Prospective Multicenter Study Concerning Virulence Genes, Phylogeny, and Gene Plasticity.

Staphylococcus aureus and cystic fibrosis (CF) are closely interlinked. To date, however, the impact of S. aureus culture in CF airways on lung function and disease progression has only been elucidated to a limited degree. This analysis aims to identify bacterial factors associated to clinical deterioration. Data were collected during an observational prospective multi-center study following 195 patients from 17 centers. The average follow-up time was 80 weeks. S. aureus isolates (n = 3180) were scanned for the presence of 25 virulence genes and agr-types using single and multiplex PCR. The presence of specific virulence genes was not associated to clinical deterioration. For the agr-types 1 and 4, however, a link to the subjects' clinical status became evident. Furthermore, a significant longitudinal decrease in the virulence gene quantity was observed. Analyses of the plasticity of the virulence genes revealed significantly increased plasticity rates in the presence of environmental stress. The results suggest that the phylogenetic background defines S. aureus pathogenicity rather than specific virulence genes. The longitudinal loss of virulence genes most likely reflects the adaptation process directed towards a persistent and colonizing rather than infecting lifestyle.

Clinical evaluation of a newly developed chairside test to determine periodontal pathogens.

BACKGROUND: The subgingival microbiota as well as determination of markers such as associated pathogens is still in the focus of dental research. The aim of this controlled clinical trial was to determine clinical applicability of a newly developed chairside bacterial test (CST) for the most relevant periodontal pathogens. METHODS: Within 125 participants (100 with periodontitis, 25 healthy) two sulcus fluid samples each were collected and pooled for further analysis. Samples were analyzed with CST and results (positive signals for every pathogen/control) were visually detected by eye. As a reference quantitative polymerase chain reaction (qPCR) was performed. RESULTS: The detection limit of CST revealed 1.2 × 104 for Treponema denticola (T.d.) and Tannerella forsythia (T.f.), 2.5 × 104 for Porphyromonas gingivalis (P.g.), 5.3 × 103 for Prevotella intermedia (P.i.), and 5.8 × 104 for Aggregatibacter actinomycetemcomitans (A.a.). Based on this maximum potential of positive detections, the sensitivities of CST in reference to qPCR were: T.d. (91.3%); T.f. (86.3%); P.g. (83.8%); P.i. (85.7%), and A.a. (100%). In regard to the clinical diagnosis, the CST assay and the qPCR method reached a sensitivity of 87.82% and 94%, respectively. The specificity for both methods was 100%. CONCLUSION: This newly developed CST can detect five typical periodontal pathogens with a somewhat lower sensitivity towards qPCR that can be classified as "good."

A Ruthenium Catalyst for Olefin Metathesis Featuring an Anti-Bredt N-Heterocyclic Carbene Ligand.

A ruthenium complex bearing an "anti-Bredt" N-heterocyclic carbene was synthesized, characterized and evaluated as a catalyst for olefin metathesis. Good conversions were observed at room temperature for the formation of di- and tri-substituted olefins by ring-closing metathesis. It also allowed for the ring-opening metathesis polymerization of cyclooctadiene, as well as for the cross-metathesis of cis-1,4-diacetoxy-2-butene with allyl-benzene, with enhanced Z/E kinetic selectivity over classical NHC-based catalysts.

Targeted microbubbles: a novel application for the treatment of kidney stones.

Kidney stone disease is endemic. Extracorporeal shockwave lithotripsy was the first major technological breakthrough where focused shockwaves were used to fragment stones in the kidney or ureter. The shockwaves induced the formation of cavitation bubbles, whose collapse released energy at the stone, and the energy fragmented the kidney stones into pieces small enough to be passed spontaneously. Can the concept of microbubbles be used without the bulky machine? The logical progression was to manufacture these powerful microbubbles ex vivo and inject these bubbles directly into the collecting system. An external source can be used to induce cavitation once the microbubbles are at their target; the key is targeting these microbubbles to specifically bind to kidney stones. Two important observations have been established: (i) bisphosphonates attach to hydroxyapatite crystals with high affinity; and (ii) there is substantial hydroxyapatite in most kidney stones. The microbubbles can be equipped with bisphosphonate tags to specifically target kidney stones. These bubbles will preferentially bind to the stone and not surrounding tissue, reducing collateral damage. Ultrasound or another suitable form of energy is then applied causing the microbubbles to induce cavitation and fragment the stones. This can be used as an adjunct to ureteroscopy or percutaneous lithotripsy to aid in fragmentation. Randall's plaques, which also contain hydroxyapatite crystals, can also be targeted to pre-emptively destroy these stone precursors. Additionally, targeted microbubbles can aid in kidney stone diagnostics by virtue of being used as an adjunct to traditional imaging methods, especially useful in high-risk patient populations. This novel application of targeted microbubble technology not only represents the next frontier in minimally invasive stone surgery, but a platform technology for other areas of medicine.

Cyclic alkyl amino carbene (CAAC) ruthenium complexes as remarkably active catalysts for ethenolysis.

An expanded family of ruthenium-based metathesis catalysts bearing cyclic alkyl amino carbene (CAAC) ligands was prepared. These catalysts exhibited exceptional activity in the ethenolysis of the seed-oil derivative methyl oleate. In many cases, catalyst turnover numbers (TONs) of more than 100,000 were achieved, at a catalyst loading of only 3 ppm. Remarkably, the most active catalyst system was able to achieve a TON of 340,000, at a catalyst loading of only 1 ppm. This is the first time a series of metathesis catalysts has exhibited such high performance in cross-metathesis reactions employing ethylene gas, with activities sufficient to render ethenolysis applicable to the industrial-scale production of linear α-olefins (LAOs) and other terminal-olefin products.

Ru-Based Z-Selective Metathesis Catalysts with Modified Cyclometalated Carbene Ligands.

A series of cyclometalated Z-selective ruthenium olefin metathesis catalysts with alterations to the N-heterocyclic carbene (NHC) ligand were prepared. X-Ray crystal structures of several new catalysts were obtained, elucidating the structural features of this class of cyclometalated complexes. The metathesis activity of each stable complex was evaluated, and one catalyst, bearing geminal dimethyl backbone substitution, was found to be comparable to our best Z-selective metathesis catalyst to date.

Synthesis of highly cis, syndiotactic polymers via ring-opening metathesis polymerization using ruthenium metathesis catalysts.

The first example of ruthenium-mediated ring-opening metathesis polymerization generating highly cis, highly tactic polymers is reported. While the cis content varied from 62 to >95% depending on the monomer structure, many of the polymers synthesized displayed high tacticity (>95%). Polymerization of an enantiomerically pure 2,3-dicarboalkoxynorbornadiene revealed a syndiotactic microstructure.

Highly active ruthenium metathesis catalysts exhibiting unprecedented activity and Z-selectivity.

A novel chelated ruthenium-based metathesis catalyst bearing an N-2,6-diisopropylphenyl group is reported and displays near-perfect selectivity for the Z-olefin (>95%), as well as unparalleled TONs of up to 7400, in a variety of homodimerization and industrially relevant metathesis reactions. This derivative and other new catalytically active species were synthesized using an improved method employing sodium carboxylates to induce the salt metathesis and C-H activation of these chelated complexes. All of these new ruthenium-based catalysts are highly Z-selective in the homodimerization of terminal olefins.

Concise syntheses of insect pheromones using Z-selective cross metathesis.

Very short synthetic routes to nine cis-olefin-containing pheromones containing a variety of functionality, including an unconjugated (E,Z) diene, are reported. These lepidopteran pheromones are used extensively for pest control, and were easily prepared using ruthenium-based Z-selective cross metathesis, highlighting the advantages of this method over less efficient ways to form Z olefins.

Stereoselective access to Z and E macrocycles by ruthenium-catalyzed Z-selective ring-closing metathesis and ethenolysis.

The first report of Z-selective macrocyclizations using a ruthenium-based metathesis catalyst is described. The selectivity for Z macrocycles is consistently high for a diverse set of substrates with a variety of functional groups and ring sizes. The same catalyst was also employed for the Z-selective ethenolysis of a mixture of E and Z macrocycles, providing the pure E isomer. Notably, an ethylene pressure of only 1 atm was required. These methodologies were successfully applied to the construction of several olfactory macrocycles as well as the formal total synthesis of the cytotoxic alkaloid motuporamine C.

Ambiphilic molecules for trapping reactive intermediates: interrupted Nazarov reaction of allenyl vinyl ketones with Me2PCH2AlMe2.

The addition of the ambiphilic molecule Me(2)AlCH(2)PMe(2) (1) to the allenyl vinyl ketone 2 gave a trapped Nazarov reaction product. Under kinetic control, the addition of the phosphine was on the methylated carbon, contrary to expected steric and electronic considerations. Computational data pointed to hydrogen bonding between the phosphine and the methyl group guiding the regiochemistry of this reaction. This product rearranged to provide the expected, regioisomeric Nazarov product. With additional 1 this compound yielded a Michael-addition product via a retro-Nazarov process.

Substituent-controlled reactivity in the Nazarov cyclisation of allenyl vinyl ketones.

Alkyl substitution α to the ketone of an allenyl vinyl ketone enhances Nazarov reactivity by inhibiting alternative pathways involving the allene moiety and through electron donation and/or steric hindrance. This substitution pattern also accelerates Nazarov cyclisation by increasing the population of the reactive conformer and by stabilising the oxyallyl cation intermediate. Furthermore, α substitution by an alkyl group does not alter the regioselectivity of interrupted Nazarov reactions when the oxyallyl cation intermediate is intercepted by addition of an oxygen nucleophile, or by [4+3] cyclisation with acyclic dienes. The regioselectivity of the Nazarov process for allenyl vinyl ketones was determined to be a result of an electronic bias in the oxyallyl cation intermediate. Computational data are consistent with this observation.

Nazarov cyclizations of an allenyl vinyl ketone with interception of the oxyallyl cation intermediate for the formation of carbon-carbon bonds.

Treatment of an allenyl vinyl ketone with BF(3) x Et(2)O leads to a cyclic oxyallyl cation by a Nazarov reaction, and when this reaction is conducted in the presence of an acyclic diene, [4 + 3] and [3 + 2] products are obtained efficiently with high regio- and stereoselectivity. The proportion of [4 + 3] to [3 + 2] product depends on the substitution on the diene. Cyclic dienes react with the oxyallyl cation by forming only one carbon-carbon bond, but the site of bond formation can be affected by steric hindrance. Electron-rich alkenes intercept the allyl cation by forming one carbon-carbon bond, or two carbon-carbon bonds through [3 + 2] cyclization. In some instances, further treatment of the initial products with BF(3) x Et(2)O leads to equilibrated products in good yield.

Miscibility and alignment effects of mixed monolayer cyanobiphenyl liquid-crystal-capped gold nanoparticles in nematic cyanobiphenyl liquid crystal hosts.

Against the rule: Liquid crystal hosts (5CB and 8CB) are doped with different thiol decorated gold nanoparticles (see figure). The "simple" hexanethiol and dodecanethiol capped nanoparticles (Au1 and Au2) are more compatible to the nematic cyanobiphenyl liquid crystals than nanoparticles capped simultaneously with alkylthiols and a nematic cyanobiphenyl thiol (Au3 and Au4).This study focuses on the miscibility of liquid crystal (LC) decorated gold nanoparticles (NPs) in nematic LCs. To explore if LC functional groups on the gold NP corona improve the compatibility (miscibility) with structurally related LC hosts, we examined mixtures of two LC hosts, 5CB and 8CB, doped at 5 wt % with different types of gold NPs. Four alkanethiol-capped NPs were synthesized; two homogeneously coated with alkanethiols (Au1 with C(6)H(13)SH and Au2 with C(12)H(25)SH), and two that were additionally capped at a different ratio with a mesogenic cyanobiphenyl end-functionalized alkanethiol HS10OCB (C(6)H(13)SH + HS10OCB for Au3 and C(12)H(25)SH + HS10OCB for Au4). Investigating these mixtures in the bulk for settling of the NPs, and in thin films using polarized optical microscopy (POM) between untreated glass slides as well as POM studies and electro-optic tests in planar ITO/polyimide test cells, reveal that the alkanethiol capped NPs Au1 and Au2 are more compatible with the two polar cyanobiphenyl hosts in comparison to the NPs decorated with the cyanobiphenyl moieties. All NPs induce homeotropic alignment in 5CB and 8CB between untreated glass slides, with Au1 and Au2 showing characteristic birefringent stripes, and Au3 and A4 exhibiting clear signs of aggregation. In rubbed polyimide cells, however, Au3 and Au4 fail to induce homeotropic alignment and show clear signs of macroscopic aggregation.

Synthesis of 5-hydroxycyclopent-2-enones from allenyl vinyl ketones via an interrupted Nazarov cyclization.

Treatment of an allenyl vinyl ketone with trifluoroacetic acid leads to Nazarov cyclization, and the intermediate carbocation is trapped efficiently by trifluoroacetate. Hydrolysis of the ester with methanol and basic alumina provides, in good to excellent overall yield, a 5-hydroxycyclopent-2-enone in which the alcohol is predominantly trans to a substituent at C-4.