Use of (1)H NMR to facilitate solubility measurement for drug discovery compounds.

The use of (1)H NMR experiments to determine the solubility of potential drug candidates using a panel of solubilizing agents is proposed as an alternative to an HPLC-UV method. The advantages of using this approach will be discussed and results comparing the two methodologies will be presented. This effort highlights the importance of a simple method for determining a suitable formulation for discovery compounds for studies using a minimal amount of material in support of early in vivo studies.

Probing natural product biosynthetic pathways using Fourier transform ion cyclotron resonance mass spectrometry.

Two natural products, diazepinomicin (1) and dioxapyrrolomycin (2), containing stable isotopic labels of (15)N or deuterium, were used to demonstrate the utility of Fourier transform ion cyclotron resonance mass spectrometry for probing natural product biosynthetic pathways. The isotopic fine structures of significant ions were resolved and subsequently assigned elemental compositions on the basis of highly accurate mass measurements. In most instances the mass measurement accuracy is less than one part per million (ppm), which typically makes the identification of stable-isotope labeling unambiguous.

Synthesis and structure-activity relationships of ring-opened 17-hydroxywortmannins: potent phosphoinositide 3-kinase inhibitors with improved properties and anticancer efficacy.

The phosphoinositide 3-kinase (PI3K) signaling pathway is frequently up-regulated in human cancer and is a promising target for the treatment of cancer. Wortmannin and its analogues are potent inhibitors of PI3K but suffer from inherent defects such as instability, insolubility, and toxicity. Opening of the reactive furan ring of 17-hydroxywortmannin with amines gives compounds with improved properties such as greater stability and aqueous solubility and a larger therapeutic index.

Enantiomeric separation and determination of absolute stereochemistry of asymmetric molecules in drug discovery: building chiral technology toolboxes.

The application of Chiral Technology, or the (extensive) use of techniques or tools for the determination of absolute stereochemistry and the enantiomeric or chiral separation of racemic small molecule potential lead compounds, has been critical to successfully discovering and developing chiral drugs in the pharmaceutical industry. This has been due to the rapid increase over the past 10-15 years in potential drug candidates containing one or more asymmetric centers. Based on the experiences of one pharmaceutical company, a summary of the establishment of a Chiral Technology toolbox, including the implementation of known tools as well as the design, development, and implementation of new Chiral Technology tools, is provided.

Integrity profiling of high throughput screening hits using LC-MS and related techniques.

Integrity profiling of HTS hits is valuable for verification of the hit identity and purity. This provides early discovery researchers with more confident SAR theories. Methodology for integrity profiling of HTS hits must be high throughput, consume little material, and selectively provide structure-based data.

Tigecycline MIC testing by broth dilution requires use of fresh medium or addition of the biocatalytic oxygen-reducing reagent oxyrase to standardize the test method.

Tigecycline is a broad-spectrum glycylcycline antibiotic with activity against not only susceptible gram-positive and gram-negative pathogens but also strains that are resistant to many other antibiotics. In the process of determining quality control (QC) limits for the American Type Culture Collection reference strains for tigecycline, a number of inconsistencies in MICs were encountered which appeared to be related to the age of the Mueller-Hinton broth (MHB) medium used in the MIC testing. The objective of this study was to determine the cause of the discrepant MIC results between fresh and aged MHB.

In vitro permeability of poorly aqueous soluble compounds using different solubilizers in the PAMPA assay with liquid chromatography/mass spectrometry detection.

Purpose: This study compares the use of UV-VIS detection with liquid chromatography/mass spectrometry (LC/MS) detection for the PAMPA (Parallel Artificial Membrane Permeability Assay) permeability determination of compounds in the drug discovery stage. LC/MS detection offers a selective and sensitive method for the determination of the PAMPA permeability for compounds that do not contain a UV chromophore or possess a low UV extinction coefficient. To enhance the reliability of our permeability measurements for compounds with low aqueous solubility, we demonstrated the use of LC/MS detection as a means for facilitating the study of solubilizing agents to enhance aqueous solubility that normally would interfere with UV-VIS detection.

Use of a linear gradient flow program for liquid chromatography-mass spectrometry protein-binding studies.

A rapid screening method to measure drug-protein binding using an immobilized human serum albumin (HSA) column was developed. This method utilizes a linear gradient flow-rate to accelerate the elution of strong binders to the HSA column. Post-column addition of a pressure relief valve enables mass spectrometric detection at relatively high mobile phase flow-rates (i.