Organofluorine Hydrazone Derivatives as Multifunctional Anti-Alzheimer's Agents with CK2 Inhibitory and Antioxidant Features

A set of novel hydrazone derivatives were synthesized and analyzed for their biological activities. The compounds were tested for their inhibitory effect on the phosphorylating activity of the protein kinase CK2, and their antioxidant activity was also determined in three commonly used assays. The hydrazones were evaluated for their radical scavenging against the DPPH, ABTS and peroxyl radicals. Several compounds have been identified as good antioxidants as well as potent protein kinase CK2 inhibitors. Most hydrazones containing a 4-N(CH₃)₂ residue or perfluorinated phenyl rings showed high activity in the radical-scavenging assays and possess nanomolar IC₅₀ values in the kinase assays.     

Characterization and Quantification of Selenoprotein P: Challenges to Mass Spectrometry

Selenoprotein P (SELENOP) is an emerging marker of the nutritional status of selenium and of various diseases, however, its chemical characteristics still need to be investigated and methods for its accurate quantitation improved. SELENOP is unique among selenoproteins, as it contains multiple genetically encoded SeCys residues, whereas all the other characterized selenoproteins contain just one. SELENOP occurs in the form of multiple isoforms, truncated species and post-translationally modified variants which are relatively poorly characterized. The accurate quantification of SELENOP is contingent on the availability of specific primary standards and reference methods. Before recombinant SELENOP becomes available to be used as a primary standard, careful investigation of the characteristics of the SELENOP measured by electrospray MS and strict control of the recoveries at the various steps of the analytical procedures are strongly recommended. This review critically discusses the state-of-the-art of analytical approaches to the characterization and quantification of SELENOP. While immunoassays remain the standard for the determination of human and animal health status, because of their speed and simplicity, mass spectrometry techniques offer many attractive and complementary features that are highlighted and critically evaluated.     

UNIQUENESS OF DISPLACEMENT-HEAT FLUX AND STRESS-TEMPERATURE PROBLEMS IN THERMOELASTICITY WITH ONE RELAXATION TIME

Two uniqueness theorems of linear thermoelasticity with one relaxation time corresponding to natural initial boundary value problems described in terms of two different pairs of thermoelastic variables: displacement-heat flux and stress-temperature are proved.     

Presence of two forms of methylated (–)‐epigallocatechin‐3‐gallate in green tea

Crude catechins extract from Chinese green tea were fractionated using Sephadex LH‐20 column chromatography. The fraction containing (–)‐epigallocatechin‐3‐gallate (EGCG) was then subjected to a semipreparative high‐performance liquid chromatography (HPLC). Using a mobile phase of water : dimethyl formamide : methanol : acetic acid (157 : 49 : 2 : 1 v/v/v/v( the mixture of two methylated catechins was separated and isolated. According to mass spectrometry (MS) and nuclear magnetic resonance (¹H‐NMR) date, these compounds were identified as (–)‐epigallocatechin‐3‐(3‐O‐methylgallate) and (–)‐epigallocatechin‐3‐(4‐O‐methylgallate).     

Partial characterization of natural antioxidants in canola meal

Defatted canola meal was extracted with 95% (v/v) ethanol at 80 °C. The extract was fractionated on a Sephadex LH-20 column using methanol as eluate. Seven major fractions were isolated according to UV absorption, content of phenolics and sugars. Antioxidant activity of these fractions was evaluated in a β-carotenelinoleate model system. Fraction IV showed the best antioxidant effect by exhibiting the highest preventive activity against the bleaching of β-carotene. Further separation of this fraction on TLC indicated that it contains several compounds including phenolic acids and trihydroxy phenolic compounds such as flavones and flavonols.     

Evolution of soluble carbohydrates during the development of pea, faba bean and lupin seeds

Seeds of pea (Pisum sativum L. cv. Ergo), faba bean (Vicia faba ssp. minor Harz., cv. Tibo) and yellow pea lupin (Lupinus luteus L. cv. Juno) were sampled at different days after flowering (DAF) and their content of soluble carbohydrates was determined: Analysis of samples showed thatmyo-inositol, fructose, glucose, galactose and sucrose were found in high abundance early in development and their content decreased gradually during maturation. -Galactosides, which includes the content of raffinose, stachyose and verbascose, started to appear later in seed development, at 37 DAF in peas, 40 DAF in faba beans and 45 DAF in lupins. Their accumulation increased considerably during seed growth, and the maximum content was obtained in mature seeds; 3.8% in peas, 4.5% in faba beans and 10.4% in lupins. Results obtained for these sugars during seed development were fitted to modelling curves in order to predict sugar content at different development stages.     

Determination of selenomethionine and selenocysteine in human serum using speciated isotope dilution-capillary HPLC-inductively coupled plasma collision cell mass spectrometry

A method for the accurate determination of selenoamino acids in human serum by HPLC-ICPMS was developed using the species-specific isotope dilution analysis principle. A serum sample was enzymatically digested with a mixture of lipase and protease after derivatization of the selenocysteine residues with iodoacetamide. The selenoamino acid fraction was isolated by size exclusion LC followed by the separation of selenomethionine and the carboxymethylated selenocysteine by capillary HPLC. The isotope-specific determination of 77Se and 80Se was achieved on-line by ICP collision cell MS allowing the removal of polyatomic interferences. Quantification was carried out by isotope dilution using a 77Se-labeled selenomethionine spike and the determination of the 77Se/80Se ratio in the cHPLC selenomethionine peak. The accurately determined selenomethionine was used as an internal standard for the selenocysteine determination from the same chromatogram. The modification of the previously developed cHPLC-ICPMS interface allowed the reduction of the absolute detection limits twice (down to the 75-fg level), which resulted in the lowest ever reported procedural detection limits (below 0.5 ng g(-1) for a 450-mg serum sample). The precision was less than 5% RSD. The method was validated by the mass balance of selenium (amino acid incorporated vs total).     

Identification of water-soluble selenium-containing proteins in selenized yeast by size-exclusion-reversed-phase HPLC/ICPMS followed by MALDI-TOF and electrospray Q-TOF mass spectrometry

An approach to speciation of selenium incorporated in yeast proteins was developed. The tryptic digest of a water-soluble protein fraction isolated by size-exclusion chromatography was analyzed by reversed-phase HPLC/ICPMS. The selenopeptides selected owing to the detector's elemental specificity were then analyzed by MALDI-TOFMS in order to select target ions for collision-induced dissociation MS. The latter, carried out with an electrospray Q-TOF spectrometer, enabled the sequencing of the selenopeptides detected by HPLC/ICPMS. The approach allowed for the first time the identification of a family of Se-containing proteins resulting from the replacement by selenomethionine of 2-9 methionine residues in a salt-stress-induced protein SIP18 (Mr 8874). The presence of these proteins was confirmed by MALDI-TOFMS of the original (nondigested) protein fraction. Another selenium protein identified was a heat-shock protein HSP12 (Mr 11693) in which the only methionine residue was replaced by selenomethionine. These two Se-containing proteins accounted for more than 95% of selenium in the water-soluble protein fraction.     

Development of a sheathless interface between reversed-phase capillary HPLC and ICPMS via a microflow total consumption nebulizer for selenopeptide mapping

A sheathless interface based on a total consumption micronebulizer operating at flow rates in the range 0.5-7.5 microL min(-1) was developed between capillary HPLC and ICPMS. It allowed the efficient nebulization and transport into the plasma of mobile phases containing up to 100% organic solvent without either cooling the spray chamber or oxygen addition. The coupled system was applied to selenopeptide mapping in a protein fraction isolated from a selenized yeast extract. The detection limits were 150 (80Se) and 200 fg (82Se) for a quadrupole instrument with and without a collision cell, respectively, which is a factor 100-150 less than that reported elsewhere for HPLC-ICPMS. The minimal peak broadening ( approximately 5 s at the half-height) allowed baseline resolution of a mixture containing more than 30 selenopeptides, many of which could not be separated using the conventional HPLC-ICPMS coupling.