A series of 2-(quinazolin-4-ylamino)-[1,4] benzoquinone derivatives that function as potent covalent-binding, irreversible inhibitors of the kinase domain of vascular endothelial growth factor receptor-2 (VEGFR-2) has been prepared by ceric ammonium nitrate oxidation of substituted (2,5-dimethoxyphenyl)(6,7-disubstituted-quinazolin-4-yl)amines and by displacement of the chlorine atom of substituted 2-chloro-5-(6,7-disubstituted-quinazolin-4-ylamino)-[1,4]benzoquinones with various amines, anilines, phenols, and alcohols. Enzyme studies were conducted in the absence and presence of glutathione and plasma. Several of the compounds inhibit VEGF-stimulated autophosphorylation in intact cells. Kinetic experiments were performed to study the reactivity of selected inhibitors toward glutathione. Reactivities correlated with LUMO energies calculated as averages of those of individual conformers weighted by the Boltzmann distribution. These results and molecular modeling were used to rationalize the biological observations. The compounds behave as non-ATP-competitive inhibitors. Unequivocal evidence, from mass spectral studies, indicates that these inhibitors form a covalent interaction with Cys-1045. One member of this series displays antitumor activity in an in vivo model.

Ion mobility-mass spectrometry (IM-MS) data is interpreted as evidence that gas-phase bradykinin fragment 1-5 (BK1-5, RPPGF) [M ϩ H] ϩ ions exist as three distinct structural forms, and the relative abundances of the structural forms depend on the solvent used to prepare the matrix-assisted laser desorption ionization (MALDI) samples. Samples prepared from organic rich solvents (90% methanol/10% water) yield ions having an ion mobility arrival-time distribution (ATD) that is dominated by a single peak; conversely, samples prepared using mostly aqueous solvents (10% methanol/90% water) yield an ATD composed of three distinct peaks. The BK1-5 [M ϩ H] ϩ ions were also studied by gas-phase hydrogen/deuterium (H/D) exchange ion-molecule reactions and this data supports our interpretation of the IM-MS data. Plausible structures for BK1-5 ions were generated by molecular dynamics (MD). Candidate MD-generated structures correlated to measured cross-sections suggest a compact conformer containing a ␤-turn whereas a more extended, open form does not contain such an interaction. This study illustrates the importance of intra-molecular interactions in the stabilization of the gas-phase ions, and these results clearly illustrate that solution-phase parameters (i.e., MALDI sample preparation) greatly influence the structures of gas-phase ions. tudies of peptide and protein structure play a major role in modern molecular biophysics and drive development of new, more specific and sensitive techniques. Gas-phase techniques for sequencing peptides and proteins are well established, and significant progress has been made in developing similar techniques for characterization of secondary (2°) and tertiary (3°) structures of gas-phase peptides/proteins [1][2][3][4][5]. Such studies increase our understanding of intra-molecular interactions and drive development of sequencing algorithms, but the relevance of gas-phase structure, structure in the absence of solvent [6], to solution-phase structure is still an open issue. The most important role of solvent is charge stabilization, and in the gas phase, charge stabilization occurs by intramolecular interactions [7]. Rapid progress is being made in the development of techniques that allow selective solvation (in terms of number of solvent molecules) of gas-phase peptide/protein ions [8], and these studies may serve to further our understanding of how solvent affects structure and function. In addition, gas-phase studies could enhance our understanding of intra-molecular interactions (i.e., hydrogen bonding, van der Waals interactions and hydrophobic forces), as well as how such interactions influence conformations in the solution phase or low dielectric environments (i.e., gas phase, membranes, and/or multimeric complexes).Bradykinin (amino acid sequence RPPGFSPR) has been extensively studied using both experimental and computational techniques. Bradykinin is an excellent model peptide for structural studies because the presence of arginine (R) at both the N-and C-terminus can potent...

ABSTRACT:RRx-001 has shown promise as a novel cancer therapeutic agent. The disposition of RRx-001 was evaluated in vitro and after intravenous administration to rats. At both 24 and 168 h after a single intravenous administration of 14 C-RRx-001 (10 mg/kg), the majority of radiolabel was in the blood.

1. Quizartinib absorption, metabolism and excretion were characterized in six healthy men receiving a single oral dose of 60 mg (≈100 μCi) of [C]-quizartinib. Blood, plasma, urine and faeces were collected ≤336 h postdose. 2. Four hours postdose, maximum mean ± SD blood radioactivity concentrations were 296 ± 67.4 ng equivalents/g. A mean ± SD of 1.64 ± 0.482% and 76.3 ± 6.23% of the dose was recovered in urine and faeces, respectively, within 336 h postdose. 3. Radio-detector high-performance liquid chromatography (radio-HPLC) and liquid chromatography-mass spectrometry (LC-MS) showed two main radioactive peaks in plasma, unchanged quizartinib and mono-oxidative metabolite, AC886. Five additional metabolites in plasma were identified by LC-MS, but low levels prevented radio-HPLC detection. Although unchanged quizartinib was the main radioactive component in faeces (mean, 4.0% of administered dose), 15 metabolites representing a mean of 1.0-3.5% of administered dose were found. Quizartinib was predominantly metabolized by phase I biotransformations (oxidation, reduction, dealkylation, deamination, hydrolysis and combinations thereof). 4. This study indicated that quizartinib was rapidly and orally bioavailable, extensively metabolized, with AC886 as the major circulating metabolite, and predominantly eliminated in faeces. Quizartinib was well tolerated in the subjects.