NaBH4 Dotaz Zobrazit nápovědu
A cost-effective method for separation of sanguinarine and chelerythrine from commercial Macleaya cordata extract (sanguiritrin) is described. In the first step, the alkaloids are reduced with NaBH4 to dihydro derivatives, which are easily separated by column chromatography on silica gel with chloroform and chloroform-methanol elution. In the second step, the dihydro derivatives are photochemically oxidized to the title alkaloids.
A novel approach to the synthesis of (purin-6-yl)acetates was developed based on Pd-catalyzed cross-coupling reactions of 6-chloropurines with a Reformatsky reagent. Their reduction with NaBH4 and treatment with MnO2 gave 6-(2-hydroxyethyl)purines, while reactions with amines in presence of NaCN afforded 6-(carbamoylmethyl)purines. Mesylation of the 6-(2-hydroxyethyl)purines followed by nucleophilic substitutions gave rise to several 6-(2-substituted ethyl)purines. This methodology was successfully applied to the synthesis of substituted purine bases and nucleosides for cytostatic and antiviral activity screening. None of the compounds exerted significant activity.
Laser ablation in liquid (LAL), one of the attractive methods for fabrication of nanoparticles, was used for the modification of carbon cloth (CC) by deposition of palladium nanoparticles (Pd NPs); a simple stirring method was deployed to deposit Pd NPs on the CC surface. Characterization techniques viz X-ray diffraction (XRD), Fourier transform infrared (FT-IR), scanning electron microscope (SEM), energy-dispersive X-ray spectrometry (EDS) and inductively coupled plasma atomic emission spectroscopy (ICP-AES) were applied to study the surface of the ensuing samples which confirmed that LAL technique managed to fabricate and deposit the Pd NPs on the surface of CC. In addition, the catalytic prowess of the carbon cloth-Pd NPs (CC/Pd NPs) was investigated in the NaBH4- or HCOOH-assisted reduction of assorted environmental pollutants in aqueous medium namely hexavalent chromium [Cr(VI)], 4-nitrophenol (4-NP), congo red (CR) and methylene blue (MB). The CC/Pd NPs system has advantages such as high stability/sustainability, high catalytic performance and easy reusability.
- MeSH
- chemické látky znečišťující vodu analýza chemie MeSH
- chrom MeSH
- katalýza MeSH
- Kongo červeň MeSH
- kovové nanočástice chemie MeSH
- lasery MeSH
- methylenová modř chemie MeSH
- nitrofenoly MeSH
- palladium chemie MeSH
- spektrometrie rentgenová emisní MeSH
- spektroskopie infračervená s Fourierovou transformací MeSH
- textilie MeSH
- uhlík MeSH
- Publikační typ
- časopisecké články MeSH
This work describes the intricacies of the determination of the trimethylselenonium ion (TMSe) in human urine via high-performance liquid chromatography-hydride generation-atomic fluorescence spectrometry (HPLC-HG-AFS). By definition, this technique requires that the separated TMSe can be online converted into a volatile compound. Literature data for the determination of TMSe via the hydride generation technique are contradictory; i.e., some authors claim that direct formation of volatile compounds is possible under reduction with NaBH4, whereas others reported that a digestion step is mandatory prior to conversion. We studied and optimized the conditions for online conversion by varying the mobile phase composition (pyridine, phosphate, and acetate), testing different reaction coils, and optimizing the hydride generation conditions, although technically no hydride (H2Se) is formed but a dimethylselenide (DMSe). The optimized conditions were used for the analysis of 64 urine samples of 16 (unexposed) volunteers and the determination of low amounts of TMSe (LOD = 0.2 ng mL-1). Total (specific gravity-corrected) selenium concentrations in the urine samples ranged from 7.9 ± 0.7 to 29.7 ± 5.0 ng mL-1 for individual volunteers. Four volunteers were characterized as TMSe producers (hINMT genotype GA) and 12 were non-producers (hINMT genotype GG). Urine of TMSe producers contained 2.5 ± 1.7 ng mL-1 of TMSe, compared to 0.2 ± 0.2 ng mL-1 for non-producers.
- MeSH
- fluorescenční spektrometrie MeSH
- lidé MeSH
- selen * moč MeSH
- sloučeniny selenu * MeSH
- vysokoúčinná kapalinová chromatografie metody MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
The diverse mechanism of antimicrobial activity of Ag and AgBr nanoparticles against gram-positive and gram-negative bacteria and also against several strains of candida was explored in this study. The AgBr nanoparticles (NPs) were prepared by simple precipitation of silver nitrate by potassium bromide in the presence of stabilizing polymers. The used polymers (PEG, PVP, PVA, and HEC) influence significantly the size of the prepared AgBr NPs dependently on the mode of interaction of polymer with Ag+ ions. Small NPs (diameter of about 60-70 nm) were formed in the presence of the polymer with low interaction as are PEG and HEC, the polymers which interact with Ag+ strongly produce nearly two times bigger NPs (120-130 nm). The prepared AgBr NPs were transformed to Ag NPs by the reduction using NaBH4. The sizes of the produced Ag NPs followed the same trends--the smallest NPs were produced in the presence of PEG and HEC polymers. Prepared AgBr and Ag NPs dispersions were tested for their biological activity. The obtained results of antimicrobial activity of AgBr and Ag NPs are discussed in terms of possible mechanism of the action of these NPs against tested microbial strains. The AgBr NPs are more effective against gram-negative bacteria and tested yeast strains while Ag NPs show the best antibacterial action against gram-positive bacteria strains.
- MeSH
- antiinfekční látky chemická syntéza chemie farmakologie MeSH
- Bacteria účinky léků MeSH
- bromidy chemie farmakologie MeSH
- Candida účinky léků MeSH
- kovové nanočástice chemie MeSH
- polymery chemie MeSH
- sloučeniny stříbra chemie farmakologie MeSH
- stříbro chemie farmakologie MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- srovnávací studie MeSH
PURPOSE: The aim was to design and thoroughly characterize monodisperse Fe3O4@SiO2-Ag nanoparticles with strong antibacterial properties, which makes them a candidate for targeting bacterial infections. METHODS: The monodisperse Fe3O4 nanoparticles were prepared by oleic acid-stabilized thermal decomposition of Fe(III) oleate; the particles were coated with silica shell using a water-in-oil reverse microemulsion, involving hydrolysis and condensation of tetramethyl orthosilicate. Resulting Fe3O4@SiO2 particles were modified by (3-mercaptopropyl)trimethoxysilane to introduce 1.1 mmol SH/g. Finally, the Fe3O4@SiO2-SH nanoparticles were decorated with silver nanoclusters formed by reduction of silver nitrate with NaBH4. The particles were analyzed by FTIR, X-ray photoelectron and atomic absorption spectroscopy, dynamic light scattering and vibrating sample magnetometry. The antibacterial activity of the Fe3O4@SiO2 and Fe3O4@SiO2-Ag nanoparticles was tested against Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli bacteria cultivated on Luria agar plates or in Luria broth. RESULTS: The superparamagnetic Fe3O4@SiO2-Ag nanoparticles (21 nm in diameter; saturation magnetization 26 A∙m2/kg) were successfully obtained and characterized. Inhibitory and toxic effects against bacteria were documented by incubation of the Fe3O4@SiO2-Ag nanoparticles with Staphylococcus aureus and Escherichia coli. CONCLUSIONS: The combination of magnetic properties together with bactericidal effects is suitable for the disinfection of medical instruments, water purification, food packaging, etc.
- MeSH
- antibakteriální látky chemie farmakologie MeSH
- Escherichia coli účinky léků MeSH
- kyselina olejová chemie MeSH
- magnetické nanočástice chemie MeSH
- oxid křemičitý chemie MeSH
- povrchové vlastnosti MeSH
- silany chemie MeSH
- Staphylococcus aureus účinky léků MeSH
- stříbro chemie farmakologie MeSH
- velikost částic MeSH
- Publikační typ
- časopisecké články MeSH
In this article, we describe the preparation and cytotoxic properties of a small focused library of lupane and 18α-oleanane triterpenoids that contain a combination of two structural motifs known to enhance the biological activities. First, we introduced two fluorine atoms to position 2 of the skeleton. Second, we synthesized a set of hemiester prodrugs, which were intended to increase the solubility and activity. Starting from betulin, we obtained two hydroxyketones (derivatives of dihydrobetulinic acid and allobetulin) and their fluorination using DAST provided 2,2-difluoro-3-oxo-compounds as the main products. Then the 3-oxo group in each derivative was reduced by NaBH4 to obtain 3β-hydroxy compounds suitable for modifying by various hemiesters. We prepared 21 compounds, 11 of them new, their cytotoxicity was tested on T lymphoblastic leukemia CCRF-CEM cells first and the most active derivatives were selected for screening on another six tumor and two non-tumor cell lines. All of them showed selectivity against cancer lines with therapeutic index between 2 and 8. All hemiesters had activity in the same range as the free hydroxyl derivatives and they would be suitable prodrugs for future in vivo experiments. Interestingly, all hemiesters of 2,2-difluorodihydrobetulonic acid had higher activity against p53 knock-out p53-/- cancer cell line than against the non-mutated analog. In active derivatives, the cell cycle was analyzed by flow cytometry and several compounds slowed down cell cycle progression through G0/G1 or S-phase.
- MeSH
- apoptóza účinky léků MeSH
- buněčný cyklus účinky léků MeSH
- fibroblasty účinky léků MeSH
- fluorované uhlovodíky chemická syntéza chemie farmakologie MeSH
- fytogenní protinádorové látky chemická syntéza chemie farmakologie MeSH
- lidé MeSH
- molekulární konformace MeSH
- nádorové buňky kultivované MeSH
- proliferace buněk účinky léků MeSH
- screeningové testy protinádorových léčiv MeSH
- triterpeny chemie MeSH
- vztah mezi dávkou a účinkem léčiva MeSH
- vztahy mezi strukturou a aktivitou MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
