WCAIR has supported enhancement of the current DDU team to support all activities within the DDU that need (bio)analytical support. This includes the following:
- Providing support and expertise for analytical systems used by synthetic medicinal chemists in the process of their work, including nuclear magnetic resonance (NMR) spectrophotometers and liquid chromatographic mass spectrometry (LCMS) systems. The key function here is helping the chemists do their work.
- Providing bioanalytical support for DMPK activities. This involves either quantifying concentrations of drug molecules and their metabolites and / or qualifying metabolites (metabolite identification) from both animal tissues (in vivo testing) and in cell cultures/extracts and/or artificial cell component mimic systems (in vitro testing).
- Run tests to measure the physicochemical properties of compounds to support synthetic chemistry activities, and supply expert advice to projects on these measurements. These tests include measurements of solubility, lipophilicity (fat solubility) and acid dissociation constants (pKa). These measurements help chemists to design molecules to have the correct properties to make sure they reach the required location within an organism.
- Check the purity of compounds to ensure compounds of the required standard are tested. This uses expertise in both NMR and LCMS.
- Perform bespoke assays in the support of work within the DDU. For example the stability of compounds in cell culture media to ensure the compound is stable enough during the duration of a test for the compound to interact with parasites within the cells. These assays often require novel approaches to the analytical method used.
A few of the projects that are ongoing or planned include:
- NMR screening. An important tool in the drug discovery process is the use of NMR to investigate the binding of small molecules (“fragments”) to target proteins. The information obtained can be used to build up suitable dug molecules from fragments that bind to the protein. Currently the methodology used requires significant amounts of protein (>10 mg), which can be difficult to obtain. Work has begun to see how this can be reduced to enable its use on more projects.
- Improving the current solubility screening method. The current primary screening method employed at the DDU adds increasing amounts of compound dissolved in an organic solvent to an aqueous test solution and looks for light scattering (nephelometry). Although this technique is good for spotting very poorly soluble compounds it tends to over-estimate their solubility, which means compounds with incorrect properties may be selected. A new method is being developed to analyse how much compound is in solution after 24 hours using LCMS, which gives more accurate solubility measurements, helping our chemists to better select the most soluble compounds to develop.
- Accurate solubility. Although a new screening method is being developed (see above) it is still necessary to determine accurate solubility results from solid samples (rather than samples dissolved in an organic solvent). The current method is being extensively modified to improve reproducibility and quality control of the process.