Qualitative and quantitative analysis of mixtures of sulfonamides. IX

In our final paper in this series we first discuss a determination of the sodium content.A rapid quantitative estimation of a mixture of sulfonamides is possible after separation of the components by means of paper chromatography without their removal from the paper. The linear relationship between the area of a spot on the chromatogram and the logarithm of the amount of compound present forms the basis of this method.     

Isomerizationi of small ring lithium dialkylamides

Lithiu N-butylcycloprpylamide ($\text{1}$) and lithium N-propylcyclobutylamide ($\text{2}$) rearrrange in ethereal solvents by nucleophilic eliminative rings fission processes; amide $\text{1}$ is highly reactive whereas amide $\text{2}$ is somewhat stable.     

Untargeted Metabolomics Strategies—Challenges and Emerging Directions

Metabolites are building blocks of cellular function. These species are involved in enzyme-catalyzed chemical reactions and are essential for cellular function. Upstream biological disruptions result in a series of metabolomic changes and, as such, the metabolome holds a wealth of information that is thought to be most predictive of phenotype. Uncovering this knowledge is a work in progress. The field of metabolomics is still maturing; the community has leveraged proteomics experience when applicable and developed a range of sample preparation and instrument methodology along with myriad data processing and analysis approaches. Research focuses have now shifted toward a fundamental understanding of the biology responsible for metabolomic changes. There are several types of metabolomics experiments including both targeted and untargeted analyses. While untargeted, hypothesis generating workflows exhibit many valuable attributes, challenges inherent to the approach remain. This Critical Insight comments on these challenges, focusing on the identification process of LC-MS-based untargeted metabolomics studies—specifically in mammalian systems. Biological interpretation of metabolomics data hinges on the ability to accurately identify metabolites. The range of confidence associated with identifications that is often overlooked is reviewed, and opportunities for advancing the metabolomics field are described.

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Graphical Abstract ?

     

Toward fully synthetic glycoproteins by ultimately convergent routes: a solution to a long-standing problem

A method is disclosed for the convergent synthesis of multiply glycosylated peptides. The approach centers on a convergent technique for generating masked, complex glycopeptide-containing C-terminal acyl donors. Activation of the latent donor in situ and use directly in segment coupling with a second peptide bearing a complex carbohydrate produces a completely unprotected, bifunctional glycopeptide. The system demonstrates a minimum level of hydrolysis and epimerization at the C-terminal amino acid residue of the acyl donor during fully convergent segment coupling and is therefore a powerful tool for the synthesis of glycoproteins.     

Discovery of a potent,non-peptide bradykinin B1 receptor antagonist

Bradykinin (BK) plays an important role in the pathophysiological processes accompanying pain and inflammation. Selective bradykinin B1 receptor antagonists have been shown to be anti-nociceptive in animal models and could be novel therapeutic agents for the treatment of pain and inflammation. We have explored chemical modifications in a series of dihydroquinoxalinone sulfonamides to evaluate the effects of various structural changes on biological activity. The optimization of a screening lead compound, facilitated by a homology model of the BK B1 receptor, culminated in the discovery of a potent human BK B1 receptor antagonist. Results from site-directed mutagenesis studies and experiments in an animal pain model are presented.     

The preparation, characterization and X-ray structural analysis of tetrakis[1-methyl-3-(2-propyl)-2(3H)-imidazolethione]zinc(II) tetrafluoroborate and tetrakis[1-methyl-3-(1-butyl)-2(3H)- imidazolethione]zinc(II) tetrafluoroborate

Two compounds, [Zn(mipit)₄][BF₄]₂ (1) and [Zn(mnbit)₄][BF₄]₂ (2) have been synthesized and characterized via standard solid and solution state methods including single crystal X-ray crystallography (mipit: 1-methyl-3-(2-propyl)-2(3H)-imidazolethione and mnbit: 1-methyl-3-(1-butyl)-2(3H)-imidazolethione). Compound 1 crystallizes in monoclinic space group P2₁/n with a = 11.804(2) ?, b = 16.710(3) ?, c = 25.763(5) ?, γ = 90.14(3)° and Z = 4, whereas compound 2 crystallizes in tetragonal space group $${\rm I}\bar{4}$$ with a = b = 11.6517(16) ?, c= 16.820(3) ?, and Z = 2. Both complexes are high melting, colorless water soluble 2:1 electrolyte solids that state have flattened tetrahedral ZnS₄ coordination geometry. The isopropyl analog is slightly more distorted than the n-butyl analog, and the degree of distortion is not directly related to the steric bulk of the ligand.