High pressure liquid chromatographic analysis ofin vivo metabolites ofN(substituted phenyl)-N′-(1,3,5-trimethyl pyrazole-4-yl)thioureas in rats

Abstract

The aim of this study was to investigate the in vivo metabolism of N-(substituted phenyl)-N'-(1,3,5-trimethylpyrazole-4-yl)thioureas (substrate) as model compounds in rats via HPLC. The substrates, N-(4-fluoro/chlorophenyl)-N'-(1,3,5-trimethylpyrazole-4-yl)thioureas (T2 and T3), and their possible metabolites were synthesized and the structures of the compounds were elucidated both by spectral and elemental analysis. Substrates were dissolved in 5% gum arabic and administered 100 mg/kg intraperitoneally (i.p.) in a volume of 0.1 ml/100 g. Blood samples were withdrawn before and at 30 min, 1, 2, 4, 8, 12 and 24 h post-dose. Chromatographic separation of the substrate and its metabolites was performed using a Hichrom chromasil C18 column (150 mm x 4.6 mm i.d., 5 microm particle size). The optimal composition of the mobile phase was achieved by using different mixtures of pure methanol and water. From the biotransformation of these thiourea compounds, N-dealkylation metabolites N-(4-fluoro/chloro-phenyl)-N'-(3,5-dimethylpyrazole-4-yl)thioureas (TI and T4) were identified together with unchanged substrate (T2 and T3) in the plasma by comparing them to reference standards via HPLC UV/DAD.

Synthesis and Profiling of a Novel Potent Selective Inhibitor of CHK1 Kinase Possessing Unusual N-trifluoromethylpyrazole Pharmacophore Resistant to Metabolic N-dealkylation

“…SCH900776 contains the N-methylpyrazole motif, which is one of the most frequent pharmacophores used in medicinal chemistry (15). However, this moiety has been shown to undergo oxidative demethylation (16) and the resulting metabolite can be the source of undesirable off-target effects (as shown in this study) and/or its formation can cause (at least partly) decreased bioavailability of the parent compound. To overcome these limitations, we have synthesized compound MU380, a fluorinated analogue of SCH900776 possessing highly unusual N-trifluoromethylpyrazole motif, which was envisioned not to undergo metabolic oxidative dealkylation and thereby provide greater robustness to the compound.…”