排序方式: 共有263条查询结果,搜索用时 15 毫秒
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Lucie Cahlíkov Rudolf Vrabec Filip Pidaný Rozlie Peinov Negar Maafi Abdullah Al Mamun Aneta Ritomsk Viriyanata Wijaya Gerald Blunden 《Molecules (Basel, Switzerland)》2021,26(17)
Alzheimer’s disease (AD) is a progressive age-related neurodegenerative disease recognized as the most common form of dementia among elderly people. Due to the fact that the exact pathogenesis of AD still remains to be fully elucidated, the treatment is only symptomatic and available drugs are not able to modify AD progression. Considering the increase in life expectancy worldwide, AD rates are predicted to increase enormously, and thus the search for new AD drugs is urgently needed. Due to their complex nitrogen-containing structures, alkaloids are considered to be promising candidates for use in the treatment of AD. Since the introduction of galanthamine as an antidementia drug in 2001, Amaryllidaceae alkaloids (AAs) and further isoquinoline alkaloids (IAs) have been one of the most studied groups of alkaloids. In the last few years, several compounds of new structure types have been isolated and evaluated for their biological activity connected with AD. The present review aims to comprehensively summarize recent progress on AAs and IAs since 2010 up to June 2021 as potential drugs for the treatment of AD. 相似文献
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Edward Mikuli ?ukasz Hetmańczyk Aneta Kowalska 《Journal of Physics and Chemistry of Solids》2007,68(1):96-103
Middle infrared absorption, Raman scattering and proton magnetic resonance relaxation measurements were performed for [Zn(NH3)4](BF4) in order to establish relationship between the observed phase transitions and reorientational motions of the NH3 ligands and BF4− anions. The temperature dependence of spin-lattice relaxation time (T1(1H)) and of the full width at half maximum (FWHM) of the bands connected with ρr(NH3), ν2(BF4) and ν4(BF4) modes in the infrared and in the Raman spectra have shown that in the high temperature phase of [Zn(NH3)4](BF4)2 all molecular groups perform the following stochastic reorientational motions: fast (τR≈10−12 s) 120° flips of NH3 ligands about three-fold axis, fast isotropic reorientation of BF4− anions and slow (τR≈10−4 s) isotropic reorientation (“tumbling”) of the whole [Zn(NH3)4]2+ cation. Mean values of the activation energies for uniaxial reorientation of NH3 and isotropic reorientation of BF4− at phases I and II are ca. 3 kJ mol−1 and ca. 5 kJ mol−1, respectively. At phases III and IV the activation energies values for uniaxial reorientation of both NH3 and of BF4− equal to ca. 7 kJ mol−1. Nearly the same values of the activation energies, as well as of the reorientational correlation times, at phases III and IV well explain existence of the coupling between reorientational motions of NH3 and BF4−. Splitting some of the infrared bands at TC2=117 K suggests reducing of crystal symmetry at this phase transition. Sudden narrowing of the bands connected with ν2(BF4), ν4(BF4) and ρr(NH3) modes at TC3=101 K implies slowing down (τR?10−10 s) of the fast uniaxial reorientational motions of the BF4− anions and NH3 ligands at this phase transition. 相似文献
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Aneta Kurpanik Marek Matussek Piotr Lodowski Grayna Szafraniec-Gorol Micha Krompiec Stanisaw Krompiec 《Molecules (Basel, Switzerland)》2020,25(22)
PAHs (polycyclic aromatics hydrocarbons), the compound group that contains perylene and its derivatives, including functionalized ones, have attracted a great deal of interest in many fields of science and modern technology. This review presents all of the research devoted to modifications of PAHs that are realized via the Diels–Alder (DA) cycloaddition of various dienophiles to the bay regions of PAHs, leading to the π-extension of the starting molecule. This type of annulative π-extension (APEX) strategy has emerged as a powerful and efficient synthetic method for the construction of polycyclic aromatic hydrocarbons and their functionalized derivatives, nanographenes, and π-extended fused heteroarenes. Then, [4 + 2] cycloadditions of ethylenic dienophiles, -N=N-, i.e., diazo-dienophiles and acetylenic dienophiles, are presented. This subject is discussed from the organic synthesis point of view but supported by theoretical calculations. The possible applications of DA cycloaddition to PAH bay regions in various science and technology areas, and the prospects for the development of this synthetic method, are also discussed. 相似文献
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The synthesis and characterization of the copper and silver trimethylsilylchalcogenolates (EtPh2P)3MESiMe3 and (Et2PhP)3MESiMe3 (M = CuI, AgI) are reported. These chalcogenolate complexes can be prepared in high yield; however, they are thermally unstable. Low-temperature single-crystal X-ray analysis of (EtPh2P)3CuSSiMe3 (1b) and (Et2PhP)3CuSeSiMe3 (2a) confirms the terminal coordination of the chalcogen ligand and the tetrahedral coordination about the metal. Protonolysis of 2a with EtOH yields the terminal selenol complex (Et2PhP)3CuSeH (6). Reaction of 1b with EtPh2P-solubilized AgOAc yields the heterometallic cluster [Cu9Ag3S6(PEtPh2)8] (7) in good yield. 相似文献
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Wietecha-Posłuszny R Garbacik A Woźniakiewicz M Kościelniak P 《Analytical and bioanalytical chemistry》2011,399(9):3233-3240
The objective of this research was to develop, optimize, and validate a modern, rapid method of preparation of human hair
samples, using microwave irradiation, for analysis of eight tricyclic antidepressants (TCADs): nordoxepin, nortriptyline,
imipramine, amitriptyline, doxepin, desipramine, clomipramine, and norclomipramine. It was based on simultaneous alkaline
hair microwave-assisted hydrolysis and microwave-assisted extraction (MAH–MAE). Extracts were analyzed by high-performance
liquid chromatography with diode-array detection (HPLC–DAD). A mixture of n-hexane and isoamyl alcohol (99:1, v/v) was used as extraction solvent and the process was performed at 60°C. Application of 1.0 mol L−1 NaOH and microwave irradiation for 40 min were found to be optimum for hair samples. Limits of detection ranged from 0.3
to 1.2 μg g−1 and LOQ from 0.9 to 4.0 μg g−1 for the different drugs. This enabled us to quantify them in hair samples within average therapeutic concentration ranges. 相似文献
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Anthocyanins are particularly abundant in different fruits, especially in berries. The beneficial effects of these compounds for human health have been known from at least the 16th century. Despite the great number of papers devoted to the different biological effects exerted by anthocyanins only a limited number of studies is focused on the antimicrobial activity of these compounds. Anthocyanin content of berry fruits varies from 7.5 mg/100 mg fresh fruit in redcurrant (Ribes rubum) up to 460 mg/100 g fresh fruit in chokeberry (Aronia melanocarpa). After consumption, anthocyanins are intensively metabolized, mainly in the intestines and liver. Glucorination, methylation and sulfation are the most typical metabolic reactions. Antimicrobial activity of crude extracts of plant phenolic compounds against human pathogens has been intensively studied to characterize and develop new healthy food ingredients as well as medical and pharmaceutical products. However, there is very little information available about the antimicrobial activity of the pure anthocyanins. In the last part of this review we present the collection of papers describing the anthocyanin profiles of different fruits (mainly berries) and the antimicrobial properties of the identified compounds. Generally, anthocyanins are active against different microbes, however Gram-positive bacteria usually are more susceptible to the anthocyanin action than Gram-negative ones. Mechanisms underlying anthocyanin activity include both membrane and intracellular interactions of these compounds. Antimicrobial activity of berries and other anthocyanin-containing fruits is likely to be caused by multiple mechanisms and synergies because they contain various compounds including anthocyanins, weak organic acids, phenolic acids, and their mixtures of different chemical forms. Therefore, the antimicrobial effect of chemically complex compounds has to be critically analyzed. 相似文献
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Dr. Jarosław J. Panek Dr. Aneta Jezierska‐Mazzarello Prof. Aleksander Koll Prof. Galina Dovbeshko Dr. Olena Fesenko 《Chemphyschem》2011,12(13):2485-2495
Adsorption of guest molecules on host surfaces can lead to dramatic changes in the spectral properties of the guest. One such effect is surface‐enhanced infrared absorption (SEIRA), observed when the guest is adsorbed on, for example, thin films, metal surfaces, or nanotubes. p‐Nitrobenzoic acid (p‐NBA) exhibits a SEIRA effect when adsorbed on Ag and Au. Herein, the IR spectra of p‐NBA adsorbed on a homemade rough Au surface, recorded in reflection mode with an angle of incidence of 16.5°, are reported. This SEIRA experiment reveals more bands than found by previous SEIRA studies. The intensities of both symmetric and asymmetric COO? and NO2 stretching, in‐plane CH, and C?C ring stretching modes are enhanced. Theoretical models constructed on the basis of density functional theory reveal the binding mode of p‐NBA to gold “particles”. The p‐NBA anion binds to gold much more strongly than the neutral form, and interaction via the carboxylic oxygen atoms is preferred over the nitro group–gold contact. A significant charge transfer during chemisorption is found, which is considered to be crucial in leading to a high SEIRA enhancement factor. 相似文献