Discovery of Cycloalkyl[c]thiophenes as Novel Scaffolds for Hypoxia-Inducible Factor-2α Inhibitors

Hypoxia-inducible factors (HIFs) are heterodimeric transcription factors induced in diverse pathophysiological settings. Inhibition of HIF-2α has become a strategy for cancer treatment since the discovery that small molecules, upon binding into a small cavity of the HIF-2α PAS B domain, can alter its conformation and disturb the activity of the HIF dimer complex. Herein, the design, synthesis, and systematic SAR exploration of cycloalkyl[c]thiophenes as novel HIF-2α inhibitors are described, providing the first chemotype featuring an alkoxy-aryl scaffold. X-ray data confirmed the ability of these inhibitors to induce perturbation of key amino acids by appropriately presenting key pharmacophoric elements in the hydrophobic cavity. Selected compounds showed inhibition of VEGF-A secretion in cancer cells and prevention of Arg1 expression and activity in IL4-stimulated macrophages. Moreover, in vivo target gene modulation was demonstrated with compound 35r. Thus, the disclosed HIF-2α inhibitors represent valuable tools for investigating selective HIF-2α inhibition and its effect on tumor biology.

AEgIS at ELENA: outlook for physics with a pulsed cold antihydrogen beam

The efficient production of cold antihydrogen atoms in particle traps at CERN's Antiproton Decelerator has opened up the possibility of performing direct measurements of the Earth's gravitational acceleration on purely antimatter bodies. The goal of the AEgIS collaboration is to measure the value of g for antimatter using a pulsed source of cold antihydrogen and a Moiré deflectometer/Talbot-Lau interferometer. The same antihydrogen beam is also very well suited to measuring precisely the ground-state hyperfine splitting of the anti-atom. The antihydrogen formation mechanism chosen by AEgIS is resonant charge exchange between cold antiprotons and Rydberg positronium. A series of technical developments regarding positrons and positronium (Ps formation in a dedicated room-temperature target, spectroscopy of the n=1-3 and n=3-15 transitions in Ps, Ps formation in a target at 10 K inside the 1 T magnetic field of the experiment) as well as antiprotons (high-efficiency trapping of [Formula: see text], radial compression to sub-millimetre radii of mixed [Formula: see text] plasmas in 1 T field, high-efficiency transfer of [Formula: see text] to the antihydrogen production trap using an in-flight launch and recapture procedure) were successfully implemented. Two further critical steps that are germane mainly to charge exchange formation of antihydrogen-cooling of antiprotons and formation of a beam of antihydrogen-are being addressed in parallel. The coming of ELENA will allow, in the very near future, the number of trappable antiprotons to be increased by more than a factor of 50. For the antihydrogen production scheme chosen by AEgIS, this will be reflected in a corresponding increase of produced antihydrogen atoms, leading to a significant reduction of measurement times and providing a path towards high-precision measurements.This article is part of the Theo Murphy meeting issue 'Antiproton physics in the ELENA era'.

Quantification of dissolved natural organic matter (DOM) mediated phototransformation of phenylurea herbicides in lakes

For many important classes of pesticides including phenylurea herbicides (PUHs) and triazines, photosensitized transformation may be the only relevant elimination process in surface waters. In this study, the dissolved organic matter (DOM) mediated phototransformation of PUHs has been investigated in laboratory and field experiments. The results indicate that, in surface waters, the photosensitized transformation of PUHs may be significant and occurs primarily by an initial one-electron oxidation most likely involving excited triplet states of DOM (3DOM*) constituents. Using isoproturon and diuron as model compounds, it is shown that for a given DOM, quantum yield factors determined in the laboratory at a few selected wavelengths can be used to quantify the overall DOM- mediated phototransformation of a given PUH under sunlight irradiation. Furthermore, it is demonstrated that this process can be modeled for a given surface water, by applying the program GCSOLAR and a simple algorithm for cloud cover for quantification of average daily light intensities. Finally, the model has been successfully applied to predict vertical concentration profiles of isoproturon and diuron in a small lake in Switzerland. To our knowledge, this is the first study in which DOM-mediated phototransformation of organic pollutants has been quantitatively validated in the field.

Determination of phenylurea herbicides in natural waters at concentrations below 1 ng l(-1) using solid-phase extraction, derivatization, and solid-phase microextraction-gas chromatography-mass spectrometry

A procedure is presented which allows the ultratrace level determination of phenylurea herbicides (PUHs) in natural waters. Samples were enriched by solid-phase extraction (SPE) on Carbopack B and alkylated with iodoethane and sodium hydride to yield thermostable products. After derivatization, the aqueous samples were extracted and injected by SPME. The use of iodoethane instead of iodomethane allowed the differentiation between parent compounds and the N-demethylated metabolites. Limits of detection were between 0.3 and 1.0 ng/l for the parent compounds. Standard deviations below 10% were achieved for samples containing more than 4 ng/l in very different matrices including Nanopure water, lake water, and waste water treatment plant (WWTP) effluent. Moreover, the para-hydroxylated metabolite of diuron could be quantified with the same procedure. The presence of further metabolites was assessed qualitatively. Chromatography was stable over a large number of measurements even with dirty samples from WWTP effluent. The precision and sensitivity of the developed analytical method allowed the investigation of the fate of PUHs in lakes, their degradation during drinking water treatment and their transport within the North Sea.

Sorption and desorption behavior of organotin compounds in sediment-pore water systems

Sediments contaminated with organotin compounds (OTs), in particular triorganotins (TOTs), are abundant in areas with high shipping activities. To assess the possible remobilization of these highly toxic compounds from such sediments, a profound understanding of their sorption/desorption behavior is necessary. In this work the extent and reversibility of sorption of OTs to sediments has been investigated using contaminated freshwater harbor sediments and two certified OT containing marine sediments. Experiments conducted with perdeuterated OTs showed that sorption of OTs to sediments is a fast and reversible process involving primarily particulate organic matter (POM) constituents as sorbents. The organic carbon-normalized sediment-water distribution ratios (DOC, expressed in L/kgOC) determined in the laboratory were consistent with in-situ DOCs obtained from OT concentrations measured in sediment and pore water samples from two dated sediment cores. For both butyl- and phenyltin compounds the log DOC values were in the range of 4.7-6.1, and the following sequence was observed: DOC (tri-OT) > or = DOC (di-OT) > or = DOC (mono-OT). However, the differences were much less pronounced than would have been expected for hydrophobic partitioning of the corresponding compounds into POM. These results support our hypothesis from earlier work with dissolved humic acids that OT sorption to sediments occurs primarily by reversible formation of (innerspere) complexes between the tin atom and carboxylate and phenolate ligands present in POM. Because of the high DOC values (i.e. log DOC > or = 4) the diffusion of OTs from deeper sediments to the surface will be rather slow, and thus a major release from undisturbed sediments is not expected. However, because OTs readily desorb, any resuspension of contaminated sediments (e.g., by the tide, storms or dredging activities) will lead to enhanced OT concentrations in the overlaying water column. Furthermore, in contrastto polycyclic aromatic hydrocarbons (PAH) where large fractions may be tightly bound (in)to soot or other carbonaceous materials, OTs will be more readily bioavailable due to the fast and reversible sorption/desorption behavior.

Simultaneous quantification of neutral and acidic pharmaceuticals and pesticides at the low-ng/l level in surface and waste water

A new analytical method is presented that allows simultaneous determination of neutral and acidic pharmaceuticals and pesticides in natural waters. The compounds investigated include frequently used pharmaceuticals, i.e., the anti-epileptic carbamazepine, four analgesic/anti-flammatory drugs (ibuprofen, diclofenac, ketoprofen and naproxen) and the lipid regulator clofibric acid and important pesticides including triazines, acetamides and phenoxy acids. Sample enrichment was achieved in one step with a newly developed solid-phase extraction procedure using the Waters Oasis HLB sorbent. The neutral compounds were analyzed by GC-MS in a first step, and then the acidic compounds after derivatization with diazomethane. Relative recoveries using isotope labeled internal standards were between 71 and 118% and the detection limits were in the range of 1 to 10 ng/l in drinking water, surface water and waste water treatment plant effluents (precision: 1-15%). The developed analytical method proved to be very durable during a 3-month field study and the target analytes were detected in concentrations of 5-3,500 ng/l in waste water treatment plant effluents, river water and lake water.

Simultaneous quantification of acetanilide herbicides and their oxanilic and sulfonic acid metabolites in natural waters

This paper describes a procedure for simultaneous enrichment, separation, and quantification of acetanilide herbicides and their major ionic oxanilic acid (OXA) and ethanesulfonic acid (ESA) metabolites in groundwater and surface water using Carbopack B as a solid-phase extraction (SPE) material. The analytes adsorbed on Carbopack B were eluted selectively from the solid phase in three fractions containing the parent compounds (PCs), their OXA metabolites, and their ESA metabolites, respectively. The complete separation of the three compound classes allowed the analysis of the neutral PCs (acetochlor, alachlor, and metolachlor) and their methylated OXA metabolites by gas chromatography/mass spectrometry. The ESA compounds were analyzed by high-performance liquid chromatography with UV detection. The use of Carbopack B resulted in good recoveries of the polar metabolites even from large sample volumes (1 L). Absolute recoveries from spiked surface and groundwater samples ranged between 76 and 100% for the PCs, between 41 and 91% for the OXAs, and between 47 and 96% for the ESAs. The maximum standard deviation of the absolute recoveries was 12%. The method detection limits are between 1 and 8 ng/L for the PCs, between 1 and 7 ng/L for the OXAs, and between 10 and 90 ng/L for the ESAs.