Improvement in Solubility of Poorly Water Soluble Drug by Cogrinding with Highly Branched Cyclic Dextrin

We investigated the enhancement of the solubility of glibenclamide (GCM), a poorly water soluble anti-diabetes drug, by cogrinding it with highly branched cyclic dextrin (HBCD) using a ball mill. Highly branched cyclic dextrin (HBCD) is a novel cyclic glucan produced from waxy corn starch by the cyclization reaction of a branching enzyme. When GCM crystals were coground with HBCD for 2 h, the solubility of GCM was improved to 12.4 μg/ml, while the concentration of HBCD was 5.0 mg/ml. Additionally, the GCM solubilized with HBCD was chemically stable in aqueous solution for at least 1 week at room temperature. The peak intensity assigned to crystalline GCM disappeared after cogrinding it by observing its powder X-ray diffraction pattern, which means that the crystalline structure of GCM could be disrupted. In the DSC measurement, the ground mixture showed a single endothermic peak, even though a temperature depression of the endothermic peak due to GCM crystal was observed. After the cogrinding, two sharp peaks assigned to sulfonylurea and benzoyl carbonyl stretching bands varied to broaden the peak to around 1640 cm⁻¹ in the C=O stretching region. These results suggested the formation of solid dispersion between GCM and HBCD.     

Monitoring of Methyldopa by Fast Fourier Transform Continuous Cyclic Voltammetry at Gold Microelectrode

A continuous cyclic voltammetric study of methyldopa at gold micro electrode was carried out. The drug in phosphate buffer (pH 2.0) is adsorpted at 400 mV, giving rise to change in the current of well-defined oxidation peak of gold in the flow injection system. The proposed detection method has some of advantages, the greatest one of which are as follows: first, it is no more necessary to remove oxygen from the analyte solution and second, this is a very fast and appropriate technique for determination of the drug compound in a wide variety of chromatographic analysis methods. Signal-to-noise ratio has significantly increased by application of discrete Fast Fourier transform (FFT) method, background subtraction and two-dimensional integration of the electrode response over a selected potential range and time window. Also in this work some parameters such as sweep rate, eluent pH, and accumulation time and potential were optimized. The linear concentration range was of 1.0×10－7—1.0×10－11 mol•L－1 (r＝0.9975) with a limit of detection and quantitation 0.004 nmol•L－1 and 0.03 nmol•L－1, respectively. The method has the requisite accuracy, sensitivity, precision and selectivity to assay methyldopa in tablets. The influences of pH of eluent, accumulation potential, sweep rate, and accumulation time on the determination of the methyldopa were considered.     

Incorporation of a Non‐Natural Arginine Analogue into a Cyclic Peptide Leads to Formation of Positively Charged Nanofibers Capable of Gene Transfection

Functionalization of the tetracationic cyclic peptide (Ka)₄ with a single guanidiniocarbonyl pyrrole (GCP) moiety, a weakly basic but highly efficient arginine analogue, completely alters the self‐assembly properties of the peptide. In contrast to the nonfunctionalized peptide 2 , which does not self‐assemble, GCP‐containing peptide 1 forms cationic nanofibers of micrometer length. These aggregates are efficient gene transfection vectors. DNA binds to their cationic surface and is efficiently delivered into cells.     

Development a New Method for the Determination of Chloropromazine in Trace Amounts by Fast Fourier Continuous Cyclic Voltammetry at an Au Microelectrode in a Flowing System

In this study a new technique has been developed for the determination of chloropromazine in flow‐injection systems. The technique, named fast Fourier transformation continuous cyclic voltammetry (FFTCV), basically illustrates the benefits of sensitivity, selectivity, simplicity and low detection limit. It is also important to refer to the positive points, presented only by the use of this technique. Firstly, it is no longer necessary to remove the oxygen from the test solution. Furthermore, the quick determination of any such compound in many chromatographic methods is possible. Thirdly, the corresponding detection limit is of sub‐nanomolar level. Additionally, a special computer based numerical method is also introduced for the calculation of the analyte signal and noise reduction. The electrode response was calculated in accordance with the partial and total charge exchanges on the electrode surface, after the background current subtraction from that of noise. The integration range of currents was set for all the potential scan ranges, including oxidation and reduction of Au surface electrode, to obtain a sensitive determination. The performed experiments aimed at measuring the effects of different parameters on the method sensitivity. In the end of these measurements, it was concluded that the method was linear for the concentration range of 0.32–31900 pg/mL (r = 0.996) with a limit of detection and quantitation 0.1 and 0.32 pg/mL, respectively. For the achievement of these optimum results, the parameter values were set to 100 V/s for the scan rate, 0.4 s for accumulation time, 800 mV for accumulation potential and 2 for the pH.     

Boron‐Catalyzed Regioselective Deoxygenation of Terminal 1,2‐Diols to 2‐Alkanols Enabled by the Strategic Formation of a Cyclic Siloxane Intermediate

The selective deoxygenation of polyols is a frontier in our ability to harness the stereochemical and structural complexity of natural and synthetic feedstocks. Herein, we describe a highly active and selective boron‐based catalytic system for the selective deoxygenation of terminal 1,2‐diols at the primary position, a process that is enabled by the transient formation of a cyclic siloxane. The method provides an ideal complement to well‐known catalytic asymmetric reactions to prepare synthetically challenging chiral 2‐alkanols in nearly perfect enantiomeric excess, as illustrated in a short synthesis of the anti‐inflammatory drug (R)‐lisofylline.     

Determination of Nitrite,Phosphate, and Silicate by Valveless Continuous Analysis with a Bubble-Free Flow Cell and Spectrophotometric Detection

A continuous flow analysis system, composed of a 1.2-cm laboratory-made antibubble flow cell and a spectrophotometer, was established. The system was evaluated for the determination of nitrite, phosphate, and silicate. Different from flow injection analysis and other flow analysis modes, an injection or multiposition valve was not needed. Even better, the system was free from interferences from air bubbles without the use of a debubbler device or electronic bubble gate. Without the formation of air bubbles, the chemical reaction was accelerated using a water bath. The experimental parameters for nutrient analysis, including reagent concentration, flow strategy, flow rate, and reaction temperature, were optimized based on a univariate experimental design. The carry-over effect was comprehensively evaluated and may be ignored using this protocol. The established system and analytical methods were especially suitable for laboratories with only basic instruments and limited budgets. The system had the advantages of high sample throughput (>60?h^?1); great convenience without valve utilization; long linear dynamic ranges (0.2–80?µM for nitrite, 0.3–14?µM for phosphate, and 0.5–120?µM for silicate); low detection limits (0.06?µM for nitrite, 0.08?µM for phosphate, and 0.11?µM for silicate); and high recovery values (91.5?±?1.01 to 108.7?±?3.18%). In addition to water samples, national reference materials were analyzed, and the results were in good agreement with the certified values.