In vitro analysis of cell metabolism using a long-decay pH-sensitive lanthanide probe and extracellular acidification assay.

Metabolic perturbations play a critical role in a variety of disease states and toxicities. Therefore, knowledge of the interplay between the two main cellular ATP generating pathways, glycolysis and oxidative phosphorylation, is particularly informative when examining such perturbations. Here we describe a new fluorescence-based screening assay for the assessment of glycolytic flux and demonstrate the value of such analysis in assessing the cellular "energy budget." The assay employs a long-decay pH-sensitive lanthanide probe to monitor extracellular acidification (ECA) in standard 96- or 384-well plates on a time-resolved fluorescence plate reader. The simple mix-and-measure procedure and fluorescence lifetime-based pH sensing allow the use of standard adherent cell culture techniques, providing high sample throughput and excellent assay performance. The assay also facilitates multiplexed or parallel analysis with existing oxygen consumption and ATP assays, thereby providing a detailed multiparametric assessment of cell metabolism. Data on cellular CO(2) production can also be obtained by comparing sealed and unsealed samples. The utility of the approach in assessing perturbed cell metabolism is demonstrated using a panel of metabolic effectors with known mechanisms of action. More complex metabolic stimuli, such as G protein-coupled receptor (GPCR) activation and perturbed ion homeostasis, are also examined.

Determination of the composition of acetylglycerol mixtures by (1)H NMR followed by GC investigation.

Commercially available partly acetylated glycerols (mono- and diacetins) are a mixture of glycerol, 1- and 2-acetylglycerol, 1,2- and 1,3-diacetylglycerol, and triacetin. No exact analysis method is available. Comparisons of (1)H NMR measurements obtained using deuterated dimethyl sulfoxide (DMSO-d6) and DMSO-d6/15% D2O are sufficient to identify and determine quickly all the components. Advantages compared with the commonly used NMR solvent CDCl3 for fatty acid glycerides include the solubility of all the components and a highly informative OH signal pattern in a region between 4.36 and 5.26 ppm almost free of other signals. 2-Acetylglycerol (2-acetin) is shown to disproportionate even at 50 degrees C into a mixture of glycerol and acetylglycerol thereby making it difficult to quantify by liquid chromatography (LC) and gas chromatography (GC) methods. Complete (1)H chemical shift data for all five components allow for the identification of the components in the mixture and thus the determination of the composition. The NMR method with DMSO-d6 as solvent was used for acetins, propionins, and butyrins. Semipreparative high-performance liquid chromatography (HPLC) on an RP18 column led to moderately pure 1-monoacetin and a mixture of diacylated species. Electron impact mass spectra show for all the components very characteristic fragmentation patterns with loss of AcOCH2 radicals, in contrast to the well-known pattern of longer-chained fatty acid derivatives that show preferred first-step loss of acyl-O radicals.

Stereoconservative Negishi arylation and alkynylation as an efficient approach to enantiopure 2,2'-diarylated 1,1'-binaphthyls.

Negishi arylation and alkynylation of easily synthesized chiral 2,2'-diodo-1,1'-binaphthyl rapidly proceeds in refluxing THF utilizing controlled microwave irradiation, affording enantiopure 2,2'-diarylated 1,1'-binaphthyls in good to excellent yields.

Long wavelength absorbing carbostyrils as test cases for different TDDFT procedures and solvent models.

The vertical excitation energies of 3,4-dicyano-6-methoxy and 3,4-dicyano-6,7-dimethoxy carbostyril have been computed with different approximations for the time-dependent density functional theory (TD-DFT) procedure and with different implementations of the continuum solvation model COSMO. Different DFT functionals were tested in TD-DFT and Tamm-Dancoff approximations (TDA) for the excitation energies in the gas phase. TDA-B3LYP showed the best agreement with the experimental data. Then TDA-B3LYP computations were performed combined with the COSMO model of solvation comparing a linear response (LR) and a post-configuration interaction (CI) implementation of the fast solvent reorganization. The post-CI solvent model overestimates the π→π* transitions and strongly underestimates the n→π* transition. The TDA approximation in combination with the linear response implementation of the COSMO solvation model perfectly computes the experimental results. TDA-LR is the most reliable method for the computation of the vertical excitation energies in a solvent. Comparison with explicit solvent calculations shows there is only a minor effect on the energies of the electronic interaction of the solute with the solvent.

On- and off column enantiomerization of 4,4'-bisquinolin-2-ones: A comparison of Auto-, DHPLcy2k and DCXplorer calculated thermodynamic data generated by dynamic high, performance liquid chromatography with theoretically calculated data.

Fast semipreparative HPLC enantioseparation of four axially chiral biscarbostyrils (4,4'-bisquinoline-2-ones) using ULMO as a pi-acidic Pirkle type chiral stationary phase leads to two racemizing pairs (1,2; k(obs) 1.6x10(-4) and 3.0x10(-4)s(-1) at 28 degrees C) and two stable ones (3,4). 3 was stabilized by a crown ether linkage from pos. 6 to 6', and 4 had sterically demanding bromo substituents in pos. 3 and 3'. On-column generated temperature-dependent chromatograms of 1 and 2 were fitted with Auto-DHPLCy2k and DCXplorer. For cpd 2 both programs delivered similar DeltaG values of 90 and 93kJ/mol, well comparable with the 99kJ/mol calculated with the B3LYP/6-31G (d) procedure. At temperatures of high conversion DCXplorer delivered inconsistent series of rate constants for the more tailing and less resolved tetramethoxy derivative 1. We connect this problem with an almost impossible halfwidth calculation of tailing peak pairs which are weakly resolved. However, this problem could be observed only in the case of tetramethoxy derivative 1. Stochastic generated data of Auto-DHPLCy2k could be used at a lower percentage of conversion only while the theoretical plate model did not deliver useful data at temperatures of very low conversion but fitted well high conversion chromatogram series of 1 and 2.

Structure-activity relationships and molecular docking of novel dihydropyrimidine-based mitotic Eg5 inhibitors.

Dihydropyrimidine-based compounds belong to the first discovered inhibitors of the human mitotic kinesin Eg5. Although they are used by many research groups as model compounds for chemical genetics, considerably less emphasis has been placed on the improvement of this type of inhibitor, with the exception of two recent studies. Dihydropyrimidines can be divided into class I (analogues that bind in the S configuration) and class II type inhibitors, which bind in the R configuration. Herein we report the synthesis and optimization of novel class II type dihydropyrimidines using a combination of in vitro and docking techniques.

Synthetic LXR agonist attenuates plaque formation in apoE-/- mice without inducing liver steatosis and hypertriglyceridemia.

Liver X receptors (LXRs) are important regulators of cholesterol and lipid metabolism. LXR agonists have been shown to limit the cellular cholesterol content by inducing reverse cholesterol transport, increasing bile acid production, and inhibiting intestinal cholesterol absorption. Most of them, however, also increase lipogenesis via sterol regulatory element-binding protein-1c (SREBP1c) and carbohydrate response element-binding protein activation resulting in hypertriglyceridemia and liver steatosis. We report on the antiatherogenic properties of the steroidal liver X receptor agonist N,N-dimethyl-3beta-hydroxy-cholenamide (DMHCA) in apolipoprotein E (apoE)-deficient mice. Long-term administration of DMHCA (11 weeks) significantly reduced lesion formation in male and female apoE-null mice. Notably, DMHCA neither increased hepatic triglyceride (TG) levels in male nor female apoE-deficient mice. ATP binding cassette transporter A1 and G1 and cholesterol 7alpha-hydroxylase mRNA abundances were increased, whereas SREBP1c mRNA expression was unchanged in liver, and even decreased in macrophages and intestine. Short-term treatment revealed even higher changes on mRNA regulation. Our data provide evidence that DMHCA is a strong candidate as therapeutic agent for the treatment or prevention of atherosclerosis, circumventing the negative side effects of other LXR agonists.

Modeling the chromatographic enantioseparation of aryl- and hetarylcarbinols on ULMO, a brush-type chiral stationary phase, by 3D-QSAR techniques.

The enantiomers of a series of chiral aryl- and hetaryl-carbinols were separated on a chiral stationary phase (ULMO) based on (S,S)-3,5-dinitrobenzoylated 1,2-diphenylethane-1,2-diamine. In all cases, the homochiral analogs of (S)-1-phenylethanol (mostly also S-enantiomers) were retained more. Log alpha values were modeled with the aid of the 3D-QSAR techniques CoMFA (comparative molecular field analysis) and CoMSIA (comparative molecular similarity indices analysis) as well as a descriptor based on normal mode eigenvalues (EVA). Partial least-squares analysis with two (CoMSIA) or three (CoMFA, EVA) latent variables on a set of 22 training analytes gives cross-validated correlation coefficients q(2) = 0.85-0.91 and conventional correlation coefficients r(2) = 0.94-0.99. The quantitative structure-enantioselective retention relationships derived thereby were used to predict the separation factors of the test set, containing also hetaryl-carbinols, e.g., furan and thiophene analogs, with good accuracy.