High-performance liquid chromatographic quantitation of cyclooxygenase and lipoxygenase metabolites of arachidonic acid from rat polymorphonuclear leukocytes

10-Ethyl-10-deaza-aminopterin (10-EdAM) is a novel folic acid antimetabolite currently being tested in phase II clinical trials. We have developed an isocratic high-performance liquid chromatographic method for the quantification of 10-EdAM and metabolites in plasma. Solid-phase extraction was used for sample clean-up. Adequate accuracy was obtained without the use of an internal standard. Fluorometric detection with excitation at 243 nm and emission at 488 nm was used for accurate quantification of samples containing small amounts of drug or metabolites (2.0-4.0 nM, depending on the compound). Ultraviolet detection at 350 nm was only applicable for the analysis of plasma concentrations of 10-EdAM exceeding 50 nM. The usefulness of the assay was demonstrated by the results obtained in a pharmacokinetic study. The assay could separate the parent compound from seven identified and two unknown products.     

A short large scale synthesis of (±) sarkomycin esters

(±) Sarkomycin ethyl ester has been prepared in four steps from ethyl acrylate.     

Dynamics of Arabidopsis thaliana soluble proteome in response to different nutrient culture conditions

In an effort to determine the best extraction procedure compatible with the high-reproducible 2-DE, different methods of soluble protein extraction from Arabidopsis cell culture suspensions grown in Gamborg B5 medium were tested. A reference 2-DE map was established for this soluble extract revealing 1184 spots. The most abundant protein spots were excised, trypsin-digested, and mass spectra obtained via MALDI-TOF and/or LC coupled to ESI-MS. Three hundred and thirty one proteins were identified and their functions were defined based on sequence comparisons and classified in different protein families. In order to analyze the impact of culture medium on the Arabidopsis proteome, we performed the 2-DE map from Arabidopsis cell suspensions cultured in another growth medium Murashige and Skoog (M-S) and 327 major spots were identified. Using PDQuest imaging analysis, significant increases in the amount of several housekeeping enzymes, stress/defense proteins, and heat shock proteins were found in M-S medium. Modified expression of certain proteins and detection of new isoforms involved in nitrate assimilation, nitrogen, and sulfur metabolism were also observed in the M-S medium. This study provides the first 2-DE maps of the soluble proteome of Arabidopsis cell suspensions. The comparative analysis of the Arabidopsis proteome in respect to different nutrient supplies shows that the culture medium may significantly influence the expression pattern of major soluble proteins in Arabidopsis cells. This work also constitutes an important step for further proteomic analysis concerning cell responses to abiotic or biotic stresses.     

Pharmacomodulation of a ligand targeting the HBV capsid hydrophobic pocket

Hepatitis B virus (HBV) is a small enveloped retrotranscribing DNA virus and an important human pathogen. Its capsid-forming core protein (Cp) features a hydrophobic pocket proposed to be central notably in capsid envelopment. Indeed, mutations in and around this pocket can profoundly modulate, and even abolish, secretion of enveloped virions. We have recently shown that Triton X-100, a detergent used during Cp purification, binds to the hydrophobic pocket with micromolar affinity. We here performed pharmacomodulation of pocket binders through systematic modifications of the three distinct chemical moieties composing the Triton X-100 molecule. Using NMR and ITC, we found that the flat aromatic moiety is essential for binding, while the number of atoms of the aliphatic chain modulates binding affinity. The hydrophilic tail, in contrast, is highly tolerant to changes in both length and type. Our data provide essential information for designing a new class of HBV antivirals targeting capsid–envelope interactions.

Small-molecule binding to the Hepatitis B virus core protein hydrophobic pocket, a possible strategy for targeting viral particle assembly.     

Monohalomethyllithium XCH2Li: stabilization of a potential synthetic reagent

The preparation of monohalomethyllithium XCH₂Li is achieved by Bromine-lithium exchange from the corresponding Bromohalomethane in the presence of $\text{one equivalent of lithium bromide}$ at ?110° in THF-Ether-Pentane solutions. This reagent, on coupling with various carbonyl compounds leads to halohydrins, epoxides and α-halomethyl ketones with high yields.     

Synthesis of 9- and 27-armed tetrakis(diperoxotungsto)phosphate-cored dendrimers and their use as recoverable and reusable catalysts in the oxidation of alkenes, sulfides, and alcohols with hydrogen Peroxide

A series of 3- and 9-armed dendrons, functionalized at the focal position to quaternary ammonium salts, were synthesized and characterized. The reaction of these ammonium dendrons with the heteropolyacid H(3)PW(12)O(40) in the presence of hydrogen peroxide led to a family of 9- and 27-armed air-stable polyoxometalate (POM)-cored dendrimers containing a catalytically active trianionic POM species [PO(4)[WO(O(2))(2)](4)](3-) in the core. These POM-cored dendrimers are air-stable, efficient, recoverable, and reusable catalysts for the selective oxidation of alkenes to epoxides, sulfides to sulfones, and alcohols to ketones, in an aqueous/CDCl(3) biphasic system with hydrogen peroxide as the primary oxidant. A study of the countercation effects showed that the dendritic structure increased the stability of the POM species and facilitated the recovery of the catalyst up to the eighth cycle, whereas the increased bulkiness around the POM center led to a negative kinetic dendritic effect. Within the 9-armed POM-cored dendrimer series, the reaction kinetics were susceptible to the nature of the peripheral endgroups. Indeed, the 9-armed n-propyl-terminated POM-cored dendrimer was identified as the most active catalyst. In addition, the results obtained with POM-cored dendrimers versus tetraalkylammonium POMs ([[n-(C(8)H(17))(3)NCH(3)](+)](3)[PO(4)[WO(O(2))(2)](4)](3-) and [[nC(18)H(37)(75 %) + nC(16)H(33)(25 %)](2)N(CH(3))(2)](+)](3)[PO(4)[WO(O(2))(2)](4)](3-)) clearly reveal that the dendritic structures are more stable than their nondendritic counterparts. After the reactions were complete, the dendrimer catalysts were easily recovered and recycled without a discernable lost of activity, whereas attempts to recover tetraalkylammonium POMs gave unsatisfactory results. A significant advantage of the dendritic structures is that they enable the recovery and recyclability of the POM catalyst, in contrast to the other tetraalkylammonium POMs.     

From simple monopyridine clusters [Mo6Br13(Py-R)][n-Bu4N] and hexapyridine clusters [Mo6X8(Py-R)6][OSO2CF3]4 (X = Br or I) to cluster-cored organometallic stars, dendrons, and dendrimers

Hexasubstitution of apical triflate ligands in the octahedral clusters [M]2[Mo6X8(CF3SO3)6] (M = n-Bu4N or Cs, X = Br or I) and monosubstitution in [n-Bu4N]2[Mo6Br13(CF3SO3)] was carried out in tetrahydrofuran at 60 degrees C with simple pyridines and then extended to organometallic pyridines, yielding cluster-cored stars, and to dendronic polyallyl- and polyferrocenylpyridines, yielding cluster-cored polyallyl and polyferrocenyl dendrimers and dendrons. The orange pyridine-substituted clusters, whose pyridine protons are deshielded in 1H NMR (a practical tool for characterization), are air-stable and thermally stable with simple pyridines, light- and air-sensitive with organometallic pyridines, and air-fragile and thermally fragile with large dendronized pyridines.