Development of novel β2-adrenergic receptor agonists for the stimulation of glucose uptake - The importance of chirality and ring size of cyclic amines

β2-Adrenergic receptor (β2AR) agonists have been reported to stimulate glucose uptake (GU) by skeletal muscle cells and are therefore highly interesting as a possible treatment for type 2 diabetes (T2D). The chirality of compounds often has a great impact on the activity of β2AR agonists, although this has thus far not been investigated for GU. Here we report the GU for a selection of synthesized acyclic and cyclic β-hydroxy-3-fluorophenethylamines. For the N-butyl and the N-(2-pentyl) compounds, the (R) and (R,R) (3d and 7e) stereoisomers induced the highest GU. When the compounds contained a saturated nitrogen containing 4- to 7-membered heterocycle, the (R,R,R) enantiomer of the azetidine (8a) and the pyrrolidine (9a) had the highest activity. Altogether, these results provide pivotal information for designing novel β2AR agonist for the treatment of T2D.

Synthesis and Electrochemical Study of 1,1′-Thienyl-Substituted Fused Bis-germatranes with a Core 5c-6e Hyperbond

Novel fused bis-germatranes containing three hypercoordinated atoms (two Ge and one N) and substituted at the 1,1′-positions with bromo-thienyl groups [(3-bromo-2-thienyl)-, (3,5-dibromo-2-thienyl)-, and 3-(4-bromo)-2-thienyl] have been synthesized from the corresponding triethoxy(thienyl)germanes and tris(1,3-dihydroxypropan-2-yl)amine. The doubly degenerated HOMO and HOMO-1 in these compounds are localized on the thienyl substituents while a 5c-6e hyperbond of the bis-germatranyl core (C–Ge←N→Ge–C system) is only a lower lying HOMO-2. Square-wave pulse voltammetry in CH3CN/0.1 M Bu4NPF6 shows all three compounds to undergo reversible electrochemical oxidation affecting one thienyl substituent. The DFT B3LYP/Lanl2DZ//HF/6-311G(d,p) calculations of their cation radicals suggest the enhancement and shortening of the N→Ge intramolecular dative bond on the side of the oxidized thienyl unit because of the positive charge and the increased acceptor character of the latter; this is accompanied by the loss of the N→Ge dative bond on the side of the non-oxidized substituent and a substantial pyramidalization of the Ge atom.

High-throughput screening of a Corynebacterium glutamicum mutant library on genomic and metabolic level

Due to impressive achievements in genomic research, the number of genome sequences has risen quickly, followed by an increasing number of genes with unknown or hypothetical function. This strongly calls for development of high-throughput methods in the fields of transcriptomics, proteomics and metabolomics. Of these platforms, metabolic profiling has the strongest correlation with the phenotype. We previously published a high-throughput metabolic profiling method for C. glutamicum as well as the automatic GC/MS processing software MetaboliteDetector. Here, we added a high-throughput transposon insertion determination for our C. glutamicum mutant library. The combination of these methods allows the parallel analysis of genotype/phenotype correlations for a large number of mutants. In a pilot project we analyzed the insertion points of 722 transposon mutants and found that 36% of the affected genes have unknown functions. This underlines the need for further information gathered by high-throughput techniques. We therefore measured the metabolic profiles of 258 randomly chosen mutants. The MetaboliteDetector software processed this large amount of GC/MS data within a few hours with a low relative error of 11.5% for technical replicates. Pairwise correlation analysis of metabolites over all genotypes showed dependencies of known and unknown metabolites. For a first insight into this large data set, a screening for interesting mutants was done by a pattern search, focusing on mutants with changes in specific pathways. We show that our transposon mutant library is not biased with respect to insertion points. A comparison of the results for specific mutants with previously published metabolic results on a deletion mutant of the same gene confirmed the concept of high-throughput metabolic profiling. Altogether the described method could be applied to whole mutant libraries and thereby help to gain comprehensive information about genes with unknown, hypothetical and known functions.

MetaboliteDetector: comprehensive analysis tool for targeted and nontargeted GC/MS based metabolome analysis

We have developed a new software, MetaboliteDetector, for the efficient and automatic analysis of GC/MS-based metabolomics data. Starting with raw MS data, the program detects and subsequently identifies potential metabolites. Moreover, a comparative analysis of a large number of chromatograms can be performed in either a targeted or nontargeted approach. MetaboliteDetector automatically determines appropriate quantification ions and performs an integration of single ion peaks. The analysis results can directly be visualized with a principal component analysis. Since the manual input is limited to absolutely necessary parameters, the program is also usable for the analysis of high-throughput data. However, the intuitive graphical user interface of MetaboliteDetector additionally allows for a detailed examination of a single GC/MS chromatogram including single ion chromatograms, recorded mass spectra, and identified metabolite spectra in combination with the corresponding reference spectra obtained from a reference library. MetaboliteDetector offers the ability to operate with highly resolved profile mass data. Finally, all analysis results can be exported to tab delimited tables. The features of MetaboliteDetector are demonstrated by the analysis of two experimental metabolomics data sets. MetaboliteDetector is freely available under the GNU public license (GPL) at http://metabolitedetector.tu-bs.de.