A formal synthesis of psymberin

A formal synthesis of psymberin (irciniastatin A) is presented. Notable features of the synthesis include the chemo-, regio-, and stereoselective oxidation of a 1,3-disubstituted allene, a configuration-dependent spirodiepoxide opening, the efficient syntheses of functionalized trans-2,6-disubstituted pyrans, and the union of a highly functionalized aldehyde with a pentasubstituted aryl homoenolate to give a dihydroisocumarin. [structure: see text]     

Accurate and sensitive determination of sildenafil,tadalafil, vardenafil,and avanafil in illicit erectile dysfunction medications and human urine by LC with quadrupole‐TOF‐MS/MS and their behaviors in simulated gastric conditions

The widespread use of phosphodiesterase‐5 inhibitors has attracted broad attention of counterfeiters to develop illicit erectile products with inaccurate amounts, unknown toxicity, and purity of active ingredients. Correspondingly, intake of these products endangers consumer health and needs to be screened for precautionary actions to reduce this risk. Therefore, in this study, a sensitive and rapid analytical method has been developed for simultaneous determination of selected phosphodiesterase‐5 inhibitors present in illicit erectile medications and human urine. Quantification of the analytes was performed by liquid chromatography coupled with quadrupole‐time‐of‐flight tandem mass spectrometry system. The chromatographic separation was successfully achieved with a run period of 8 min. Low detection limits were obtained in the range of 1.63–9.81 ng/g with relative standard deviations below 7.72% obtained using the replicate measurements of lowest concentration in calibration plots. The analytical performance of the proposed method proved good linearity, low detection limits, good accuracy and precision with high percent recoveries for human urine samples. Developed method was successfully applied to real samples including four different brands of illicit erectile medications. The results obtained revealed the presence of high levels of sildenafil in analyzed samples. The behaviors of selected phosphodiesterase‐5 inhibitors were also studied in simulated gastric conditions.     

Spectral Imaging to Measure Heterogeneity in Membrane Lipid Packing

Physicochemical properties of the plasma membrane have been shown to play an important role in cellular functionality. Among those properties, the molecular order of the lipids, or the lipid packing, is of high importance. Changes in lipid packing are believed to compartmentalize cellular signaling by initiating coalescence and conformational changes of proteins. A common way to infer membrane lipid packing is by using membrane‐embedded polarity‐sensitive dyes, whose emission spectrum is dependent on the molecular order of the immediate membrane environment. Here, we report on an improved determination of such spectral shifts in the emission spectrum of the polarity‐sensitive dyes. This improvement is based on the use of spectral imaging on a scanning confocal fluorescence microscope in combination with an improved analysis, which considers the whole emission spectrum instead of just single wavelength ranges. Using this approach and the polarity‐sensitive dyes C‐Laurdan or Di‐4‐ANEPPDHQ, we were able to image—with high accuracy—minute differences in the lipid packing of model and cellular membranes.     

Identification of Chemical Forms of Lead, Cadmium and Nickel in Sewage Sludge of Waste Water Treatment Facilities

 Lead, cadmium and nickel levels in sewage sludge of a waste water treatment facility were determined by slotted tube atom trap (STAT)-flame atomic absorption spectrometry after using different extraction reagents. In addition, a sequential extraction procedure was applied to the same samples and the results were compared. It was found that Pb and Cd were relatively mobile as organically bound, carbonate or adsorbed on the Fe–Mn oxides and the concentrations in the extracts were higher than 50%. However, the percentage of Ni bound to these phases was found to be very low. Received October 23, 2001; accepted August 2, 2002     

Volatile constituents of aerial parts of three endemic Centaurea species from Turkey: Centaurea amanicola Hub.-Mor., Centaurea consanguinea DC. and Centaurea ptosimopappa Hayek and their antibacterial activities

The volatile constituents of the aerial parts of Centaurea amanicola Hub.-Mor., Centaurea consanguinea DC. and Centaurea ptosimopappa Hayek were extracted by hydrodistillation and analysed by GC and GC-MS. Altogether 94 components were identified. Sesquiterpenoids, fatty acids and carbonylic compounds were the most abundant components in the oils. Hexadecanoic acid and (Z,Z )-9,12-octadecadienoic acid were the main fatty acids in all the examined samples, that showed different patterns of composition. The study on the biological activity of the oils showed an action mainly against the Gram-positive pathogens.     

On locally finite minimal non-solvable groups

In the present work we consider infinite locally finite minimal non-solvable groups, and give certain characterizations. We also define generalizations of the centralizer to establish a result relevant to infinite locally finite minimal non-solvable groups.