Stable Mn2+ mono‐ and binuclear complexes containing pentadentate 6,6′‐((methylazanediyl)bis(methylene))dipicolinic acid coordinating units give remarkably high relaxivities due to the presence of two inner‐sphere water molecules. The mononuclear derivative binds human serum albumin (HSA) with an association constant of 3372 M ?1, which results in the replacement of the coordinated water molecules by donor atoms of protein residues. The dinuclear analogue also binds HSA while leaving one of the Mn2+ centres exposed to the solvent with two coordinated water molecules. Thus, this complex shows remarkably high relaxivities upon protein binding (39.0 mM ?1 s?1 per Mn, at 20 MHz and 37 °C). 相似文献
The mononuclear pyrazolyl complexes [PdCl2(HIPz)2] (1), [PdBr2(HIPz)2] (2), [PdI2(HIPz)2] (3), [Pd(SCN)2(HIPz)2] (4), and [Pd(NHCOIPz)2] (5) have been prepared. Compound 1 was obtained from the displacement of acetonitrile from [PdCl2(CH3CN)2] precursor by the 4-iodopyrazole (HIPz) ligand, whereas 2–5 were synthesized by substitution of the chlorido in 1 by the respective anionic group. The compounds were characterized by elemental analysis, infrared spectroscopy, and 1H NMR spectroscopy. The thermal behavior of 1–5 has been studied by TG and DTA. The thermal stability of [PdX2(HIPz)2] compounds varies according to the trends X = Cl? < I? ? SCN?< Br?. No stable intermediates were isolated during the thermal decompositions due to the overlap of the degradation processes. The final products of the thermal decompositions were characterized as metallic palladium by X-ray powder diffraction. 相似文献
Reversed‐phase‐HPLC analysis by means of superficially porous silica particle columns (fused‐core) was applied to the investigation of flavonoids, coumarins, and psoralens in lime juice samples. Hesperidin (367.0 ± 16.0 ppm) and eriocitrin (148.0 ± 7.9 ppm) were the most abundant flavonoids. Fifteen coumarins and furocoumarins were determined, including bergamottin (29.6 ± 1.1 ppm), 5‐geranyloxy‐7‐methoxycoumarin (16.5 ± 0.6 ppm), and oxypeucedanin hydrate (9.9 ± 0.5 ppm) as predominant compounds. These molecules are today well known for their beneficial effects on human health. As a consequence, the present study, beyond investigating for the first time the chemical composition of lime juice, highlights also its health‐promoting qualities, due to its content of flavonoids and coumarins. 相似文献
This work describes the synthesis of inositol derivatives condensed with 2‐mercaptobenzothiazole or 2‐mercaptobenzimidazole, potential antimicrobial agents. These compounds were prepared by ring opening of epoxide intermediate (2S,3R‐epoxy‐1‐O‐methyl‐ l ‐chiro‐inositol and 2R,3S‐epoxy‐1‐O‐methyl‐ l ‐chiro‐inositol), which were obtained from l ‐quebrachitol (1‐O‐methyl‐chiro‐inositol). Microwave irradiation was used to promote the condensation reaction. 相似文献
Abstract Highly stereoselective C[sbnd]C bond forming reactions can be performed with a variety of optically active sulfinyl derivatives to afford, after desulfurization, optically active sulfur-free products. 相似文献
The optimization of the physico‐chemical properties of both GdIII chelates and nanocarriers is of great importance for the development of effective nanosystems for magnetic resonance imaging (MRI) applications. With this aim, macrocyclic GdIII chelates were selectively attached to the pendant amino groups exposed to the external surface of spheroidal mesoporous silica nanoparticles (MSNs). This was achieved by treating the metal complexes with MSNs that contained the templating surfactant molecules confined within the silica channels (hexadecyltrimethylammonium (CTA)/MSN), followed by extraction of the surfactant. The nanoparticles showed greatly improved 1H relaxometric efficiency relative to corresponding systems that also feature GdIII chelates conjugated inside the pores. A further significant relaxivity enhancement was observed after chemical transformation of the free amino groups into amides. The ionic relaxivity of the final nanoparticles (r1p=79.1 mM ?1 s?1; 0.5 T, 310 K) is one of the highest reported so far. 相似文献
A simple hybrid synthesis processing method was developed to synthesize γ-MnO2 nanocrystalline particles. The polyol method was modified by the addition of nitric acid in order to allow the synthesizing of single-phase Mn3O4 in a large scale. In the sequence, the acid digestion technique was used to transform Mn3O4 into γ-MnO2. Structural and morphological characterization was carried out by X-ray diffractometry, Infrared and Raman spectroscopy, thermogravimetric analysis, nitrogen adsorption isotherm, scanning electron microscopy, and transmission electron microscopy. The electrochemical properties were investigated by cyclic voltammetry and galvanostatic charge–discharge measurements. The synthesized material exhibits a specific capacitance of 125.1 F?g?1 at a mass loading of 0.98 mg?cm?2. The relation between structural features and electrochemical activity is discussed by comparing the synthesized material with commercial electrolytic manganese dioxide. 相似文献
This paper reports on the synthesis and physico‐chemical, mechanical, and biological characterization of two sets of poly(amidoamine) (PAA) hydrogels with potential as scaffolds for in vivo peripheral nerve regeneration. They are obtained by polyaddition of piperazine with N,N′‐methylenebis(acrylamide) or 1,4‐bis(acryloyl)piperazine with 1,2‐diaminoethane as cross‐linking agent and exhibit a combination of relevant properties, such as mechanical strength, biocompatibility, biodegradability, ability to induce adhesion and proliferation of Schwann cells (SCs) preserving their viability. Moreover, the most promising hydrogels, that is those deriving from 1,4‐bis(acryloyl)piperazine, allow the in vitro growth of the sensitive neurons of the dorsal root ganglia, thus getting around a critical point in the design of conduits for nerve regeneration.
Drugs photostability plays two different opposite roles; a real advantage arises considering the longer expiration time of the drugs while the consequent persistence in the environment involves an obvious negative effect bound to their harmfulness.On this basis we tested the photostability and toxicity of three pharmaceutical active principles: Finasteride, Diclofenac and Naproxen. The pure active principles, as well as commercial drugs containing them, were considered; for the last, the protective effect of the packaging was also evaluated. Samples were irradiated according to the ICH Guidelines for photostability testing (The International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use); a simulating sunlight source (a mercury-vapor lamp coupled to a tungsten filament one) was used to cover the wavelength range 300–2000 nm; Temperature, Relative Humidity, Irradiance and Illuminance were maintained constant during the photodegradation. The concentrations of the pharmaceutical active principles during the photodegradation were monitored by HPLC with UV/Vis detector. Toxicity tests were performed by means of an amperometric biosensor based on suspended yeast cells. Since the products obtained by the photodegradation process can result as toxic or more toxic than the original molecules, tests were performed first and after the photodegadation.
Results
After 90 hours of exposure the concentration resulted lowered by 42.9%, 88.4% and 91% for Finasteride, Naproxen and Diclofenac respectively. Toxicity of the pure active principles follows the same order of the photostability. After photodegradation a contribute of the reaction products was evidenced.
Conclusions
The simple and cheap analytical procedure here proposed, allowed to obtain not only data on photostability and toxicity of the pure active principles but, even if roughly, also useful information on the reactions kinetic and toxicity of the photodegradation products.