Resolution of Historically Discordant Ames Test Negative / Rodent Carcinogenicity Positive N-nitrosamines using a Sensitive, OECD-aligned Design.

The in vitro Bacterial Reverse Mutation (Ames) Test is crucial for evaluating the mutagenicity of pharmaceutical impurities. For N-nitrosamines (NAs) historical data indicated that for certain members of this chemical class the outcomes of the Ames Test did not correlate with their associated rodent carcinogenicity outcomes. This has resulted in negative outcomes in an OECD aligned Ames Test alone (standard or enhanced) no longer being considered sufficient by regulatory authorities to assess potential carcinogenic risk of NAs if present as impurities in drug products.

Detection of low-level PTFE contamination: An application of solid-state NMR to structure elucidation in the pharmaceutical industry.

We report a novel use of solid-state ¹⁹F nuclear magnetic resonance to detect and quantify polytetrafluoroethylene contamination from laboratory equipment, which due to low quantity (up to 1% w/w) and insolubility remained undetected by standard analytical techniques. Solid-state ¹⁹F NMR is shown to be highly sensitive to such fluoropolymers (detection limit 0.02% w/w), and is demonstrated as a useful analytical tool for structure elucidation of unknown solid materials.

NMR screening applied to the fragment-based generation of inhibitors of creatine kinase exploiting a new interaction proximate to the ATP binding site.

Using an in-house fragment NMR library, we identified a set of ligands that bind rabbit muscular creatine kinase, an enzyme involved in key ATP-dependent processes. The ligands docked to the crystal structures of creatine kinase indicated that a phenylfuroic acid could enter into a pocket adjacent to the nucleotide binding site. This fragment served as an anchor to develop in silico a series of potential inhibitors which could partly access the nucleotide binding site.

F-ara-AMP is a substrate of cytoplasmic 5'-nucleotidase II (cN-II): HPLC and NMR studies of enzymatic dephosphorylation.

Intracellular accumulation of triphosphorylated derivatives is essential for the cytotoxic activity of nucleoside analogues. Different mechanisms opposing this accumulation have been described. We have investigated the dephosphorylation of monophosphorylated fludarabine (F-ara-AMP) by the purified cytoplasmic 5'-nucleotidase cN-II using HPLC and NMR.