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991.
In this work, the Langmuir monolayer technique was applied to study the interactions between sphingomyelin and various sterols differing in the structure of the side chain (cholesterol, beta-sitosterol, stigmasterol). The mean area per molecule and the excess free energy of mixing values were analyzed in the context of sterol-induced condensing effect and interactions between molecules in the mixed monolayers. Moreover, the compression modulus values were calculated and widely discussed from the point of view of the ordering effect of sterols. It was found that all of the sterols investigated form the most stable monolayers with sphingomyelin at 2:1 sphingomyelin:sterol proportion and the strongest interactions exist between molecules in cholesterol-containing films. Moreover, cholesterol provokes the strongest area condensation and reveals the highest ordering properties, while plant sterols were found to differ only slightly with regards to their ordering properties. Additionally, the ordering effect of the sterols on dipalmitoylphosphatidylcholine (DPPC) films was analyzed and compared to that on sphingomyelin films. 相似文献
992.
Katarzyna Solarska-
ciuk Kinga Adach Sylwia Cyboran-Mikoajczyk Dorota Bonarska-Kujawa Agnieszka Rusak ucja Cwynar-Zajc Tomasz Machaowski Teofil Jesionowski Katarzyna Grzywacz Mateusz Fijakowski 《Molecules (Basel, Switzerland)》2021,26(5)
Silicon dioxide, in the form of nanoparticles, possesses unique physicochemical properties (size, shape, and a large surface to volume ratio). Therefore, it is one of the most promising materials used in biomedicine. In this paper, we compare the biological effects of both mesoporous silica nanoparticles extracted from Urtica dioica L. and pyrogenic material. Both SEM and TEM investigations confirmed the size range of tested nanoparticles was between 6 and 20 nanometers and their amorphous structure. The cytotoxic activity of the compounds and intracellular ROS were determined in relation to cells HMEC-1 and erythrocytes. The cytotoxic effects of SiO2 NPs were determined after exposure to different concentrations and three periods of incubation. The same effects for endothelial cells were tested under the same range of concentrations but after 2 and 24 h of exposure to erythrocytes. The cell viability was measured using spectrophotometric and fluorimetric assays, and the impact of the nanoparticles on the level of intracellular ROS. The obtained results indicated that bioSiO2 NPs, present higher toxicity than pyrogenic NPs and have a higher influence on ROS production. Mesoporous silica nanoparticles show good hemocompatibility but after a 24 h incubation of erythrocytes with silica, the increase in hemolysis process, the decrease in osmotic resistance of red blood cells, and shape of erythrocytes changed were observed. 相似文献
993.
Joanna J. Sajkowska-Kozielewicz Pawe Kozielewicz Katerina Makarova Marcin Stocki Nicholas M. Barnes Katarzyna Paradowska 《Molecules (Basel, Switzerland)》2021,26(1)
A new alkaloid, geissospermiculatine was characterized in Geissospermum reticulatum A. H. Gentry bark (Apocynaceae). Here, following a simplified isolation protocol, the structure of the alkaloid was elucidated through GC-MS, LC-MS/MS, 1D, and 2D NMR (COSY, ROESY, HSQC, HMBC, 1H-15N HMBC). Cytotoxic properties were evaluated in vitro on malignant THP-1 cells, and the results demonstrated that the cytotoxicity of the alkaloid (30 μg/mL) was comparable with staurosporine (10 μM). Additionally, the toxicity was tested on zebrafish (Danio rerio) embryos in vivo by monitoring their development (0–72 h); toxicity was not evident at 30 μg/mL. 相似文献
994.
Monika Rzonsowska Katarzyna Kozakiewicz Katarzyna Mitua Julia Duszczak Maciej Kubicki Beata Dudziec 《Molecules (Basel, Switzerland)》2021,26(2)
A synthesis of a series of mono-T8 and difunctionalized double-decker silsesquioxanes bearing substituted triazole ring(s) has been reported within this work. The catalytic protocol for their formation is based on the copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) process. Diverse alkynes were in the scope of our interest—i.e., aryl, hetaryl, alkyl, silyl, or germyl—and the latter was shown to be the first example of terminal germane alkyne which is reactive in the applied process’ conditions. From the pallet of 15 compounds, three of them with pyridine-triazole and thiophenyl-triazole moiety attached to T8 or DDSQ core were verified in terms of their coordinating properties towards selected transition metals, i.e., Pd(II), Pt(II), and Rh(I). The studies resulted in the formation of four SQs based coordination compounds that were obtained in high yields up to 93% and their thorough spectroscopic characterization is presented. To our knowledge, this is the first example of the DDSQ-based molecular complex possessing bidentate pyridine-triazole ligand binding two Pd(II) ions. 相似文献
995.
Grzegorz Mlosto Jakub Wrczycki Katarzyna Urbaniak Dariusz M. Bieliski Heinz Heimgartner 《Molecules (Basel, Switzerland)》2021,26(4)
Fluoride anion was demonstrated as a superior activator of elemental sulfur (S8) to perform sulfurization of thioketones leading to diverse sulfur-rich heterocycles. Due to solubility problems, reactions must be carried out either in THF using tetrabutylammonium fluoride (TBAF) or in DMF using cesium fluoride (CsF), respectively. The reactive sulfurizing reagents are in situ generated, nucleophilic fluoropolysulfide anions FS(8−x)−, which react with the C=S bond according to the carbophilic addition mode. Dithiiranes formed thereby, existing in an equilibrium with the ring-opened form (diradicals/zwitterions) are key-intermediates, which undergo either a step-wise dimerization to afford 1,2,4,5-tetrathianes or an intramolecular insertion, leading in the case of thioxo derivatives of 2,2,4,4-tetramethylcyclobutane-1,3-dione to ring enlarged products. In reactions catalyzed by TBAF, water bounded to fluoride anion via H-bridges and forming thereby its stable hydrates is involved in secondary reactions leading, e.g., in the case of 2,2,4,4-tetramethyl-3-thioxocyclobutanone to the formation of some unexpected products such as the ring enlarged dithiolactone and ring-opened dithiocarboxylate. In contrast to thioketones, the fluoride anion catalyzed sulfurization of their α,β-unsaturated analogues, i.e., thiochalcones is slow and inefficient. However, an alternative protocol with triphenylphosphine (PPh3) applied as a catalyst, offers an attractive approach to the synthesis of 3H-1,2-dithioles via 1,5-dipolar electrocyclization of the in situ-generated α,β-unsaturated thiocabonyl S-sulfides. All reactions occur under mild conditions and can be considered as attractive methods for the preparation of sulfur rich heterocycles with diverse ring-size. 相似文献
996.
997.
Magdalena Buszewska-Forajta Katarzyna Rafińska Boguslaw Buszewski 《Journal of separation science》2022,45(7):1345-1361
Matrix-assisted laser desorption/ionization - imaging mass spectrometry is an alternative tool, which can be implemented in order to obtain and visualize the “omic” signature of tissue samples. Its application to clinical study enables simultaneous imaging-based morphological observations and mass spectrometry analysis. Application of fully informative material like tissue allows obtaining the complex and unique profile of analyzed samples. This knowledge leads to diagnosing disease, studying the mechanism of cancer development, selecting the potential biomarkers as well as correlating obtained images with prognosis. Nevertheless, it is worth noticing that this method is found to be objective but the result of the analysis is mainly influenced by the sample preparation protocol, including the collection of biological material, its preservation, and processing. However, the application of this approach requires a special sample preparation procedure. The main goal of the study is to present the current knowledge on the clinical application of matrix-assisted laser desorption/ionization with imaging mass spectrometry in cancer research, with particular emphasis on the sample preparation step. For this purpose, several protocols based on cryosections and formalin-fixed paraffin-embedded tissue were compiled and compared, taking into account the measured metabolites of potential diagnostic importance for a given type of cancer. 相似文献
998.
The synthesis of a new series of chiral phosphine amides derived from d-glucosamine is described. The palladium-catalyzed asymmetric allylic alkylations of racemic (E)-1,3-diphenyl-2-propenyl acetate with dimethyl malonate using these ligands have been investigated. The results obtained and the NMR studies of free ligands and of their Pd-complexes obtained from dimer [(η3-C3H5)PdCl]2 revealed the mode of complexation and the influence of the configuration and of the nature of the substituent at the anomeric position on the enantioselectivity of the studied asymmetric allylic alkylation reactions. 相似文献
999.
1000.
The assignment of the absolute configuration of hydroxy- and aminophosphonates by their double derivatization with commercially available naproxen is presented. The correlation between the spatial arrangement around the stereogenic carbon center and the signs of the DeltadeltaRS allows determination of the absolute configuration of hydroxy- and aminophosphonates by simple comparison of the 1H and 31P NMR spectra of the (R)- and (S)-naproxen ester or amide derivatives. Extensive conformational analysis (theoretical calculations, low-temperature experiments) supported by the NMR studies of structurally diverse naproxen esters and amides of hydroxy- and aminophosphonates proved that a simplified model can be successfully used. 相似文献