Quantitative determination of itazigrel in rodent diet by reversed-phase HPLC and evaluation of its stability at 20 degrees C

A simple, accurate and precise procedure for the quantitation of itazigrel (a potent lipophilic inhibitor of collagen and arachidonic acid-induced aggregation being studied for its effects on peripheral vascular disease) from granulated rodent diet is presented. The drug was extracted from rodent diet using methanol + water (80:20) following dissolution of the diet in water. Samples of the supernatant were injected into the HPLC and the eluent was monitored with a fluorescent detector (lambda ex = 320 and lambda em = 430) to achieve analytical specificity. Interday coefficients of variation of the calibration curve slope were +/- 6% on standards between 0 and 1000 micrograms/g. Potency and homogeneity of the drug spiked diet prepared over a 1 year interval at 70, 200 and 600 micrograms/g was 99.3 +/- 2.5%, 100 +/- 1.8%, and 101 +/- 1.9% of label, respectively. Samples prepared for chromatography were stable for 24 h at 20 degrees C, and drug in diet was stable for 102 days when protected from light and stored at 20 degrees C.     

Ring-strain effects on the oxidation potential of enediynes and enediyne complexes

The metal-enediyne complexes [(eta 5-C5H5)Fe[eta 5-1,2-C5H3C identical to C(CH2)nC identical to]] (4, n = 4; 5, n = 5) and [(eta 5-C5H5)-Fe[eta 5-1,2-C5H3(C identical to C Me)2]] (6) were prepared from 1,2-diethynylferrocene (3). Complexes 4 and 5 were characterized in the solid state by X-ray crystallographic analysis. The structures of 4 and 6 were determined by computation using ab initio methods. A correlation was observed between ring-strain and increased ease of electrochemical oxidation along the series 6 (+0.164 V) to 5(+0.152 V) to 4 (+0.123 V). A similar trend in ionization potentials was identified in both the gas phase and in solution by computational methods.     

Electronic structures and spectra of cyanoethylene derivatives

Results of two different types of molecular orbital calculations of severalπ-orbital systems containing nitrile groups are reported and compared. The bidentate ligandbis-(methylmercapto) maleonitrile and related molecules are included. Electronic spectra of these molecules are reported and assigned in terms of the calculated energies.     

Ionic liquid-immobilized catalytic system for biomimetic dihydroxylation of olefins

A biomimetic catalytic system for dihydroxylation of olefins consisting of OsO4, N-methylmorpholine, and a flavin has been immobilized in an ionic liquid. This immobilized catalytic system is highly efficient for dihydroxylation with 30% aqueous H2O2 and it can be reused (at least 5 times) without loss of activity.     

Hydrotris(pyrazolyl)borate metallacycles: conversion of a late-metal metallacyclopentene to a stable metallacyclopentadiene-alkene complex

The bis(ethene) complex [(Tp)Ir(C(2)H(4))(2)] (3) undergoes reaction with dimethyl acetylenedicarboxylate (DMAD) in acetonitrile solvent at 60 degrees C to give the trispyrazolylborate metallacyclopent-2-ene complex [(Tp)Ir (CH(2)CH(2)C(CO(2)Me)=C(CO(2)Me))(NCMe)] (4). Spectroscopic analysis of a room-temperature reaction between 3 and DMAD in acetonitrile-d(3) provides evidence for the formation of an eta(2)-alkene/eta(2)-alkyne intermediate on the path to 4. The reaction of 3 with DMAD in THF solvent leads to the formation of the THF-ligated metallacyclopent-2-ene complex [(Tp)Ir(CH(2)CH(2)C(CO(2)Me)=C(CO(2)Me))(THF)] (5), which undergoes further reaction with DMAD at 60 degrees C in benzene to give [(Tp)Ir(C(CO(2)Me)=C(CO(2)Me)C(CO(2)Me)=C(CO(2)Me))(eta(2)-CH(2)=CH(2))] (6). Complex 4 was structurally characterized by X-ray crystallography.     

Synchronization by irregular inactivation

Many natural and technological systems have on/off switches. For instance, mitosis can be halted by biochemical switches which act through the phosphorylation state of a complex called mitosis promoting factor. If switching between the on and off states is periodic, chaos is observed over a substantial portion of the on/off time parameter plane. However, we have discovered that the chaotic state is fragile with respect to random fluctuations in the on time. In the presence of such fluctuations, two uncoupled copies of the system (e.g., two cells) controlled by the same switch rapidly synchronize.     

Highly Stable and Inert Complexation of Indium(III) by Reinforced Cyclam Dipicolinate and a Bifunctional Derivative for Bead Encoding in Mass Cytometry

H₂cb-te2pa, a cross-bridged cyclam functionalized by two picolinate arms, was used for the formation of an incredible inert In^III chelate. The inertness of the complex was evaluated by UV/Vis experiments in several competitive media and was highlighted by the comparison with [In(dota)]⁻ and [In(dtpa)]²⁻ (H₄dota = 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid, H₅dtpa = diethylenetriamine pentaacetic acid), which are currently used in biological applications. For the first time, a bifunctional analogue of H₂cb-te2pa was prepared by C-functionalization to keep its coordination properties intact. However, this strategy leads to the formation of two diastereoisomers as evidenced and studied by NMR experiments and DFT calculations. Kinetic studies proved nevertheless that both isomers of the complex are equally inert. They were therefore used without distinction for their covalent grafting on polystyrene beads. The so-called metal-encoded beads were tested for imaging mass cytometry. The detection of ¹¹⁵In allows the generation of images with high quality, proving the great potential of the bifunctional [In(cb-te2pa)]⁺ derivatives for single-cell analysis by mass cytometry.