Crystal structure and crystal form stability of trelagliptin succinate / 药学学报

In order to investigate trelagliptin succinate's stability in solution, recrystallization and suspension methods in polar solvent (mainly in water and 95% alcohol) were used to study the crystal form transformation of trelagliptin succinate. Single crystal X-ray diffraction, powder X-ray diffraction and thermalgravimetric analysis, and differential scanning calorimetry were used to characterize the structure of the solid state form before and after transformation. The results showed that trelagliptin succinate can easily convert to trelagliptin hemi-succinate mediated by solvent, especially by polar solvent, namely trelagliptin hemi-succinate is more stable than trelagliptin succinate in solution.

Preparation and characterization of Forms A and B of benazepril hydrochloride / 浙江大学学报·医学版

<p><b>OBJECTIVE</b>To prepare Form A and Form B of benazepril hydrochloride and to compare the differences in spectrums, thermodynamics and crystal structure between two polymorphic forms.</p><p><b>METHODS</b>Form A and Form B of benazepril hydrochloride were characterized by Fourier transform infrared spectroscopy (IR), thermal gravimetric analysis (TG), differential scanning calorimetry (DSC), powder x-ray diffraction (PXRD) and single crystal x-ray diffraction (SCXRD).</p><p><b>RESULTS</b>Preparation method, crystal structure and polymorphic stability of Form A and Form B of benazepril hydrochloride were obtained. Based on the analysis of crystal structure of both polymorphs, Form A belonged to monoclone space group P2(1) with a=7.8655(4)Å, b= 11.7700(6)Å, c= 13.5560(7)Å, β= 102.9470(10)°, V=1223.07 (11)Å(3) and Z=2, while Form B belonged to orthorhombic space group P212121, with a=7.9353(8)Å, b=11.6654(11)Å, c=26.6453(16)Å, V=2466.5(4)Å(3) and Z=4. From the DSC and XRD results, Form B of benazepril hydrochloride could be transformed into Form A after heating treatment.</p><p><b>CONCLUSION</b>Form A and Form B of benazepril hydrochloride are both anhydrous and displayed different polymorphs due to different molecular configuration. Furthermore, Form A exhibits more stable than Form B at high temperatures.</p>

Study on the mechanism of the interaction between montmorillonite and bacterium / 药学学报

<p><b>AIM</b>To investigate the mechanism of the interaction between montmorillonite and bacteria by studying the reactions of different charges of montmorillonites with bacteria.</p><p><b>METHODS</b>Bacteriostatic test: one loop of E. coli and Staphylococcus aureus at the concentration of 1 x 10(6).mL-1 was incubated to the plate culture medium containing different concentrations of montmorillonite, and incubated 24 h to observe the growth of bacteria. Bacterial adsorptive test: different amounts of montmorillonite were added into the artificially simulated intestinal solution (containing bacteria 1 x 10(7).mL-1). After the culture, the bacterial colonies were counted.</p><p><b>RESULTS</b>The results showed that montmorillonite per se showed no bacteriostatic or bactericidal effect, but after exchange with metal ion and functional groups which inhibits bacteria, then it showed these activities. Adsorption was the main way between montmorillonite and bacteria. The special way of fixing bacteria into the "carriage" of montmorillonite gel which carry this structure was its pharmacological basis of curing diarrhea. The adsorption effect was related to layer charge density of the montmorillonites.</p><p><b>CONCLUSION</b>Montmorillonite showed adsorption ability of bacteria with minus related to its layer charge, but has no bacteriostatic and bactericidal effect.</p>