Jacek Wójcik

The Polish TU 154M plane, Polish Air Force Flight 101, had crashed near Smolensk on 10th of April 2010. The crash was investigated by The Interstate Aviation Committee, whose conclusions were questioned by a number of Polish scientists. The cause of the crash still appears to be incompletely documented and requires additional evidence. In this paper, investigations of a solid material eluted from a piece of cloth of one of the victims of the crash are described. High resolution mass spectrometry was applied to analyze the soot left after controlled ethylene oxide (EO) explosions, performed under different conditions. These included electric ignition of EO vapors in a large volume steel container, and explosions of glass tubes filled with liquid EO, stimulated by thermally initiated explosions of pentaerythritol tetranitrate (PETN). One of these explosions was conducted in the vessel used for the electric ignition of EO and the other in a hermetically locked, small volume container. It was shown that the soot comprises a set of C₂H₄O homopolymers and copolymers whose characteristic MS patterns are condition-dependent. The MS spectrum of the postcrash sample referred to above reveals a number of polymers that are also present in the soot obtained in PETN-initiated ethylene oxide explosions. It can be concluded that the piece of cloth was subjected to an EO explosion initiated by an explosion of energetic material, possibly PETN. Similar control experiments with ethylene glycol (EG) showed that the polymers identified in the investigated postcrash sample could not originate from exploding EG.

A series of halogenated derivatives of natural flavonoids: baicalein and chrysin were designed and investigated as possible ligands for the catalytic subunit of tumor‐associated human kinase CK2. Thermal shift assay method, in silico modeling, and high‐performance liquid chromatography‐derived hydrophobicity together with IC₅₀ values determined in biochemical assay were used to explain the ligand affinity to the catalytic subunit of human protein kinase CK2. Obtained results revealed that substitution of baicalein and chrysin with halogen atom increases their binding affinity to hCK2α, and for 8‐chlorochrysin the observed effect is even stronger than for the reference CK2 inhibitor—4,5,6,7‐tetrabromo‐1H‐benzotriazole. The cytotoxic activities of the baicalein and chrysin derivatives in the in vitro model have been evaluated for MV4‐11 (human biphenotypic B myelomonocytic leukemia), A549 (human lung adenocarcinoma), LoVo (human colon cancer), and MCF‐7 (human breast cancer) as well as on the nontumorigenic human breast epithelial MCF‐10A cell lines. Among the baicalein derivatives, the strongest cytotoxic effect was observed for 8‐bromobaicalein, which exhibited the highest activity against breast cancer cell line MCF‐7 (IC₅₀ 10 ± 3 μM). In the chrysin series, the strongest cytotoxic effect was observed for unsubstituted chrysin, which exhibited the highest activity against leukemic cell line MV4‐11 (IC₅₀ 10 ± 4 μM).

Complex formation between quinine and natural cyclodextrins (CD) was studied using NMR spectroscopy.

Gibbs energies of complex formation between enantiomers of bicyclic terpenoid, fenchone, and naturally occurring cyclodextrins, βCD and γCD, were determined by means of¹³C and¹H nuclear magnetic resonance (NMR) titration data. These results were compared with the corresponding data obtained previously for the diastereomeric fenchone/αCD complexes. The size of the inner cavity of host molecules significantly influences stoichiometry, association constants, and enantiomeric differentiation of the studied complexes. These complementary data allow us to discuss qualitatively the influence of the host size on the guest–host interactions. A method of the simultaneous use of titration data collected for several resonances of different isotopes in the determination of association constants was worked out and thoroughly analyzed. Comparison of the results of global data analyses with weighted means of individual ones revealed that both these approaches are equally trustworthy.

A plastidial cis-prenyltransferase synthesizes a family of polyprenols that accumulate in thylakoid membranes and play a central role in the efficiency of photo

The cooperation of the mevalonate (MVA) and methylerythritol phosphate (MEP) pathways, operating in parallel in plants to generate isoprenoid precursors, has been studied extensively. Elucidation of the isoprenoid metabolic pathways is indispensable for the rational design of plant and microbial systems for the production of industrially valuable terpenoids. Here, we describe a new method, based on numerical modeling of mass spectra of metabolically labeled dolichols (Dols), designed to quantitatively follow the cooperation of MVA and MEP reprogrammed upon osmotic stress (sorbitol treatment) in Arabidopsis (Arabidopsis thaliana). The contribution of the MEP pathway increased significantly (reaching 100%) exclusively for the dominating Dols, while for long-chain Dols, the relative input of the MEP and MVA pathways remained unchanged, suggesting divergent sites of synthesis for dominating and long-chain Dols. The analysis of numerically modeled Dol mass spectra is a novel method to follow modulation of the concomitant activity of isoprenoid-generating pathways in plant cells; additionally, it suggests an exchange of isoprenoid intermediates between plastids and peroxisomes.