0000000000172330
AUTHOR
Peteris Mekss
showing 11 related works from this author
Zwitterionic Sulfonates as m/z Shift Reagents for 5-Methylcytosine Detection in Deoxyribonucleic Acids (DNA) Using Flow Injection Analysis and Electr…
2015
5-Methylcytosine (5-MC) is an important epigenetic modification of DNA. Abnormally high concentrations of this substance appear because of the hypermethylation of cytosine. Therefore, the measurement of the quantity of this compound in mammals is of great importance. Recently, we reported that several imidazolium-based zwitterionic sulfonates form complexes with 5-MC in solution, which can be studied by electrospray ionisation mass spectrometry (ESI-MS). It is shown in this paper that such an association can be utilised for the detection of 5-MC in a DNA sample using high-throughput a flow injection analysis ESI-MS method. A variety of the sulfonate zwitterions have been tested as m/ z shi…
Method development for the determination of 1,1-dimethylhydrazine by the high-performance liquid chromatography-mass spectrometry technique.
2018
Unsymmetrical dimethyl hydrazine is highly toxic, carcinogenic compound, widely used for organic synthesis and drug development. Therefore, due to its high reactivity, direct analysis is problematic. Current study proposes to use derivatization reaction to increase selectivity and sensitivity of high-performance liquid chromatography–mass spectrometry method. Different derivatization agents were tested and optimal reaction media was found. Derivatization was performed by using small amounts of reagents to lower the cost of analysis. The full validation of the method was performed and it can be used in a routine control in pharmaceutical analysis. Method sensitivity is 0.15 ppm, and lineari…
Hydrophilic Ionic Liquids in the Synthesis of Hantzsch Ester
2011
Hydrophilic Ionic Liquids in the Synthesis of Hantzsch Ester Hantzsch ester synthesis was investigated using (2-hydroxyethyl)-ammonium carboxylates, polar and hydrophilic ionic liquids possessing low toxicity and high biodegradability. The reaction rates and yields of the products in ionic liquids were greater than those in common organic solvents. The relationship between the structure of the ionic liquid used and the structure of the heterocyclic compound was investigated.
Electrospray Ionization Mass Spectrometry of Non-Covalent Complexes Formed between N-Alkylimidazolium-Containing Zwitterionic Sulfonates and Protonat…
2015
This paper describes non-covalent complexes between zwitterionic 3-(1-alkyl-3 N-imidazolio)-propane-1-sulfonates and different amines. Electrospray ionization (ESI) mass spectrometry and collision-induced dissociation were used to measure the stability of such complexes in solution and in the gas phase. Generally, zwitterionic sulfonates formed more abundant complexes with protonated 5-methylcytosine (5-MCH) than with aliphatic amines. The results show that the association constants and half-dissociation threshold energies of these complexes nonlinearly depend on the alkyl chain length of the zwitterion. It is shown that the complexes with the lowest stability exist in acetonitrile solutio…
Detection of the lunasin peptide in oats (Avena sativa L)
2013
We report the first discovery of lunasin in oats (Avena sativa L). Lunasin is a novel cancer preventive, anti-inflammatory and cholesterol-reducing peptide originally isolated from soy and later found in cereals (barley, rye, wheat, triticale). Lunasin was detected in oats using LC–MS/MS analysis. The chromatograms and mass spectra of lunasin isolated from five oat genotypes were compared with those of the synthetic lunasin peptide. We measured the lunasin content in harvests of two years and found that all tested oat genotypes contained the lunasin peptide. However, we observed genotype-related fluctuations in the lunasin content. Notably, the middle early oat variety ‘Ivory’ contained the…
ChemInform Abstract: Imidazolium and Pyridinium Salts - Solvents Influencing the Rate and Direction of the Fries, Beckmann, and Claisen Rearrangement…
2010
The effects of the structural elements of the ionic liquid media on the direction of these rearrangements and the product yields are studied.
Lewis acid-catalyzed Beckmann rearrangement of ketoximes in ionic liquids
2009
Abstract The Beckmann rearrangement of five ketoximes was done in 17 different ionic liquids by using four Lewis acids. The effect of the type of cation and the type of anion in the ionic liquid on the rate of the rearrangement reaction and product composition is compared and discussed. The effects of the hydrophobicity and the hydrogen bonding ability of ionic liquids on the rearrangement of ketoximes were investigated, as well as the catalytical activity of the Lewis acids.
Collision-Induced Dissociation of Imidazolium-Based Zwitterionic Liquids
2009
Fragmentation pathways of some imidazolium based zwitterionic liquids—3-(3-alkyl-1-imidazolio)-propane sulfonates and 3-(2-methyl-3-alkyl-1-imidazolio)-propane sulfonates—have been studied by tandem electrospray mass spectrometry and collision-induced dissociation. The relative abundances of the lowest energy fragment ions depend on the length of the alkyl chain at the IIN of the imidazolium ring and the cone voltage. The first fragment ions originate from the scission of Cnon aromatic–N bond of compounds investigated, but with increasing collision energy, scission of C–C bonds occurs. Aggregates of the general formula [(M + H) x + (M) y]+ ( x;y = 1–2) formed. Methyl substituted zwitterion…
Positive and negative electrospray ionization-collision-induced dissociation of sulfur- containing zwitterionic liquids.
2011
The mass spectrometric properties of several (1,2-dimethyl-1 H-imidazol-3-ium-3-yl)-alkane-1-sulfonates (alkane=ethyl, propyl and butyl) are investigated in this study. These substances, named zwitterionic liquids (ZILs), were synthesized using classical transformations and analyzed in positive and negative electrospray ionization mode using collision-induced dissociation (0–50 eV). We have also performed regioselective deuterium labeling of the alkyl chain of 3-(1,2-dimethyl-1 H-imidazol-3-ium-3-yl)-propane-1-sulfonates. Thus, the mass spectra of isotopically-labeled compounds were used for the confirmation of fragmentation pathways of ZILs. Briefly, the data obtained in this study show t…
Potato (Solanum tuberosum) Juice Exerts an Anticonvulsant Effect in Mice through Binding to GABA Receptors
2008
Naturally occurring benzodiazepines have been identified in regular food such as wheat and potato, but there is still no evidence that potato extracts can affect CNS responses in vivo. Here we found that undiluted potato juice and potato juice diluted with saline 1 : 2 administered 10 min intracisternally ( I. C.) and 30 min per os before bicuculline exerted significant anticonvulsant activity in the bicuculline-induced seizure threshold test in mice. In vitro, potato juice from different harvests at dilution series from 10 % to 0.000001 %, diluted 100,000-fold, displaced 50 % of gamma-aminobutyric acid (GABA) receptor ligand [ (3)H]GABA and diluted 40-fold displaced 50 % of [(3)H]flunitraz…
Alkylation of ambident indole anion in ionic liquids
2007
AbstractAlkylation of indole salts in different ionic liquids is reported. Ionic liquids increase the alkylation reaction rate of ambident indole anion and reduce the effects of counter ions and/or additives, the alkylation reaction rates being independent of the presence of small amounts of protic solvents or water.