A facile synthesis of 1,2‐azidoalcohols from their epoxides using α,α',α”‐N‐hexakis(triethylammoniummethylene chloride)‐melamine as a multi‐site phase‐transfer catalyst in water was developed. By this eco‐friendly and highly atom‐economic method, a variety of 1,2‐azidoalcohols was obtained in high yields with excellent regioselectivity and in short reaction times. Application of this six‐site PTC in the ring opening of epoxides by cyanide, acetate and chloride anions was also studied. The catalyst can be recovered after completion of the reaction and can be recycled without affecting the catalytic property. 相似文献
The original spiral tube assembly for high-speed counter-current chromatography (HSCCC) is further improved by a new tube configuration called “flat-twisted tubing” which was made by extruding the tube (1.6 mm I.D.) through a narrow slot followed by twisting along its axis forming about 1 cm twisted screw pitch. This modification interrupts the laminar flow of the mobile phase through the tube and continuously mixes the two phases through the column. The performance of this spiral tube assembly was tested by three types of two-phase solvent systems with different polarities each with a set of suitable test samples such as DNP-amino acids, dipeptides and proteins at the optimal elution modes. In general all these test samples yielded higher resolution with the lower mobile phase than the upper mobile phase. In the most hydrophobic two-phase solvent system composed of hexane–ethyl acetate–methanol–0.1 M hydrochloric acid (1:1:1:1, v/v/v/v), DNP–amino acids were separated with Rs-a (peak resolution based on the same column capacity adjusted for comparison) at 4.40 and 73% of stationary phase retention at a flow rate of 0.5 ml/min with the lower mobile phase. In the polar solvent system composed of 1-butanol–acetic acid–water (4:1:5, v/v/v), dipeptide samples were resolved with Rs-a at 4.06, compared to 2.79 with the cross-pressed tube assembly at 45% stationary phase retention, each at a flow rate of 1 ml/min. Finally in the aqueous–aqueous polymer phase systems composed of polyethylene glycol 1000 – dibasic potassium phosphate each 12.5% (w/w) in water, protein samples were resolved with Rs-a at 2.53 compared to 1.10 with the cross-pressed tube assembly at 52% of stationary phase retention, each at a flow rate of 1 ml/min. These results indicate that the present system substantially improves the partition efficiency with a satisfactory level of stationary phase retention by the lower mobile phase. 相似文献
A new fatty acid ester (1) and seven known phenolic compounds, i.e. salfredin B11 (2), nigephenol C (3), nigephenol B (4), acetovanillion (5), p-hydroxybenzoic acid (6), p-hydroxy-acetophenone (7) and p-hydroxybenzaldehyde (8), were isolated from the seeds of Nigella sativa var. hispidula. Among them, compounds 5, 7 and 8 were isolated from Nigella for the first time. Their structures were elucidated with HR-ESI-MS, 1D and 2D NMR spectra. Evaluation of the isolated compounds on protein tyrosine phosphatase (PTP1B) assay indicated that although compounds 2–8 show no promising anti-PTP1B activities, compound 1 possess anti-PTP1B activity with an IC50 value of 7.38 ± 0.14 μM in vitro. 相似文献
Background: Morinda elliptica (family Rubiaceae), locally known as ‘mengkudu kecil’, has been used by the Malays for medicinal purposes. Anthraquinones isolated from the roots of Morinda elliptica, namely nordamnacanthal and damnacanthal, have been widely reported to exhibit anticancer and antioxidant properties in various cancer models in vitro and in vivo. Aim: This study analyzed the morphological and ultrastructural effects of damnacanthal and nordamnacanthal on T-lymphoblastic leukemia CEM-SS cells. Method: Light microscopy, Giemsa staining, Wright’s staining, scanning electron microscopy, and transmission electron microscopy were carried out to determine apoptosis, necrosis, and ultrastructural changes that occurred within the cells. Results: The outcomes showed that these compounds induced cell death by apoptosis and necrosis, specifically at higher doses of 10 and 30 μg/mL. Condensation and fragmentation of the nuclear chromatin, which further separated into small, membrane-bound vesicles known as apoptotic bodies, were observed in the nuclei and cytoplasm. The plasma membranes and cytoskeletons also showed marked morphological changes upon treatment with damnacanthal and nordamnacanthal, indicating apoptosis. Conclusion: Therefore, we report that damnacanthal and nordamnacanthal exhibit anticancer properties by inducing apoptosis and necrosis in CEM-SS cells, and they have potential as a drug for the treatment of T-lymphoblastic leukemia. 相似文献
JPC – Journal of Planar Chromatography – Modern TLC - The seeds of Ocimum basilicum have traditionally been used for the prevention and treatment of a number of diseases in Xinjiang of... 相似文献
Electroglottography (EGG) was used to monitor vocal fold vibration patterns in normal subjects and patients with various laryngeal disorders. In order to evaluate the regularity of vocal fold vibration, frequency and amplitude perturbation of EGG waves during sustained phonation were measured with a laboratory computer. The data were compared to the degree of hoarseness evaluated by auditory perception and by sound spectrographic analysis. Frequency and amplitude perturbation measures showed some overlap between normal and pathological groups. However, there was a close relation between perturbation analysis of EGG waves and degree of hoarseness (Spearman's rank correlation coefficient rs = 0.73, p less than 0.0005). Amplitude perturbation was found to be a more sensitive measure of the irregularity of vocal fold vibration than frequency perturbation. 相似文献
One of the main challenges in large-scale applications of molecularly imprinted polymers (MIPs) is the significant amount of template needed in polymer preparation. A new strategy based on room-temperature ionic liquids (RTILs) was suggested to solve this problem by reducing the amount of template in the polymerization recipe. The MIP was synthesized with a mixture of dimethyl sulfoxide and RTIL (1-butyl-3-methylimidazolium tetrafluoroborate) as porogen, in which chlorogenic acid (CGA) was used as template, 4-vinylpyridine (4-VP) as functional monomer, and ethylene glycol dimethacrylate (EDMA) as cross-linker. The influence of polymerization variables, including CGA concentrations, and the ratio of 4-VP to EDMA on imprinting effect were investigated comprehensively. Moreover, the properties involving the column permeability, the number of binding sites, and the polymer morphology of the CGA-MIP monoliths were studied thoroughly. The MIP monolith had an excellent column permeability (1.53 × 10−13 m2) and allowed an ultra-fast on-line SPE, which dramatically shortens the separation time (< 10 min) and improves the separation efficiency. At high flow velocity (5.0 mL min−1), 50 μL of the extract from Eucommia ulmoides leaves can be loaded directly on the CGA-MIP monoliths and CGA with high purity can be obtained with a recovery of 89.01 ± 0.05%. As a conclusion, the resulting RTIL-induced approach of preparing MIP may be an effective tool in fabricating MIP in a low-cost way.
Metal–organic framework sorbents [MIL-100(Fe), MOF-235(Fe)], Fe3O4 nanoparticles and metal–organic framework loaded on iron oxide nanoparticles [Fe3O4@MIL-100(Fe) and Fe3O4@MOF-235(Fe)] were prepared and examined for ciprofloxacin (CIP) removal. The results showed that sorption kinetics of CIP by Fe3O4@MIL-100(Fe) follows the Elovich and pseudo-second-order models indicating that the sorption is both chemisorption and physical adsorption, whereas the sorption to other sorbents occurs mainly by physical sorption. The sorption isotherm studies revealed that Langmuir model provided the best fit to all the experimental data. The thermodynamic studies showed that CIP removal is spontaneous (ΔG° = 2.28 kJ/mol) and endothermic (ΔH° = 18.39 kJ/mol). It was also found that among the sorbents investigated for CIP removal, Fe3O4@MIL-100(Fe) has the highest maximum monolayer adsorption capacity of 322.58 mg/g. 相似文献