Preparation, crystal structure and thermostability of nirmatrelvir polymorphs / 药学学报

The polymorphism and thermostability of nirmatrelvir, the main antiviral component of the oral COVID-19 treatment drug, were studied. Four polymorphs of nirmatrelvir were prepared by recrystallization methods. Among them, Form 1 and nirmatrelvir methyl tert-butyl ether solvate (Form 2) had been reported in the literature, while nirmatrelvir isobutyl acetate solvate (NMTW-IBAC) and nirmatrelvir ethyl acetate solvate (NMTW-EA) are two new solvates. The crystal structures were characterized by single-crystal X-ray diffraction, powder X-ray diffraction, thermogravimetric analysis and differential scanning calorimetry. The thermostability of polymorphism and crystalline transformation were also investigated by combining Hirshfeld surface analysis and interaction energy analysis. The results showed that nirmatrelvir Form 1 belongs orthorhombic crystal system with the space group P212121 and one nirmatrelvir molecule included in the asymmetric unit, which has the same crystal structure as nirmatrelvir Form 4 reported in the literature. Owing to its larger thermal expansion, the differences in crystallographic parameters obtained at different temperatures were found between Form 1 and Form 4. Three solvates of nirmatrelvir belonged to the iso-structural with monoclinic crystal system and the space group P21, in which the asymmetric unit contains one nirmatrelvir molecule and one solvent molecule. The thermal analysis results showed that nirmatrelvir Form 1 was a solvent-free crystal form with the best thermal stability and the strongest intermolecular hydrogen bonding. Among the three solvates, NMTW-EA has the worst thermal stability and the weakest hydrogen bonding interaction between the nirmatrelvir molecule and the solvent molecule. The energy framework of nirmatrelvir solvates showed that the closer the arrangement between solvent and nirmatrelvir molecules, the greater the total interaction energy between solvent and nirmatrelvir molecules. The phase transition studies of the three solvates showed that NMTW-IBAC and NMTW-EA were transformed into amorphous after desolvation, respectively, while Form 2 undergoes oiling during desolvation. The research provides theoretical guidance for the analysis, identification and quality control of nirmatrelvir polymorphs.

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>

Modified montmorillonite as multifunction gene and drug delivery system / 浙江大学学报·医学版

<p><b>OBJECTIVE</b>To develop polyethylenimine-Doxorubicin-montmorillonite (PEI-Dox-MTT) as a novel multifunction delivery system.</p><p><b>METHODS</b>Dox was intercalated into montmorillonite, PEI covered to the surface of Dox/MMT to make the nano-particle. XRD, FT-IR and TGA were used to confirm chemical property of the nano-particle. SEM was used to observe the morphology. The capability of drug release was investigated by PBS buffer solution (pH 7.4). The DNA binding ability of nano-particle was detected by gel electrophoresis retardation assay. The cell viability in COS-7 and SKOV3 cell lines was tested using MTT assay. The gastric mucosa protection was evaluated in vitro.</p><p><b>RESULTS</b>XRD image showed that Dox was intercalated into montmorillonite, inter space of which increased to 31.3Å; the FT-IR spectra showed the vibration bands of PEI at 1 560 cm(-1) and 2 850 cm(-1), the vibration band of Dox at 1 350 cm(-1). Size analysis and SEM revealed that the size of nano-particle was 600 nm, and the zeta-potential was 30 mV. Drug release experiment explored that the nano-particle stably released drug in range of 6 X10(-4) ≊ 8 X10(-4) mg/ml within 72 h. MTT assay showed that the cell viability was over 80% in experiment condition in COS-7 and SKOV3 cell lines. 0.3 mg PEI-MMT nano-particle was able to protect gastric mucosa from alcohol.</p><p><b>CONCLUSION</b>Multifunction system of PEI/Dox/MMT has been prepared successfully.</p>

Synthesis of a supermolecular nanoparticle γ-hy-PC/Ada-Dox and its antitumor activity / 浙江大学学报·医学版

<p><b>OBJECTIVE</b>To synthesize a (2-Hydroxypropyl)-γ-cyclodextrin-polyethylenimine/adamantane-conjugated doxorubicin (γ-hy-PC/Ada-Dox) based supramolecular nanoparticle with host-guest interaction and to identify its physicochemical characterizations and antitumor effect.</p><p><b>METHODS</b>A novel non-viral gene delivery vector γ-hy-PC/Ada-Dox was synthesized based on host-guest interaction. 1H-NMR, NOESY, UV-Vis, XRD and TGA were used to confirm the structure of the vector. The DNA condensing ability of complexes was investigated by particle size, zeta potential and gel retardation assay. Cytotoxicity of complexes was determined by MTT assay in BEL-7402 and SMMC-7721 cells. Cell wound healing assay was performed in HEK293 and BEL-7404 cells. The transfection efficiency was investigated in HEK293 cells. H/E staining and cell uptake assay was performed in BEL-7402 cells.</p><p><b>RESULTS</b>The structure of γ-hy-PC/Ada-Dox was characterized by 1H-NMR, NOESY, UV-Vis, XRD, TGA. The drug loading was 0.5% and 5.5%. Gel retardation assay showed that γ-hy-PC was able to completely condense DNA at N/P ratio of 2; 0.5% and 5.5% γ-hy-PC/Ada-Dox was able to completely condense DNA at N/P ratio of 3 and 4,respectively. The cytotoxicity of polymers was lower than that of PEI25KDa. The transfection efficiency of γ-hy-PC was higher than that of γ-hy-PC/Ada-Dox at N/P ratio of 30 in HEK293 cells; and the transfection efficiency was decreasing when Ada-Dox loading was increasing. Cell uptake assay showed that γ-hy-PC/Ada-Dox was able to carry drug and FAM-siRNA into cells.</p><p><b>CONCLUSION</b>The novel vector γ-hy-PC/Ada-Dox has been developed successfully, which has certain transfection efficiency and antitumor activity.</p>

Platinum tetrachloride coupled PEG-PEI as drug carrier and gene delivery vector / 浙江大学学报·医学版

<p><b>OBJECTIVE</b>To construct a drug carrier and gene vector PEG-PEI-Pt.</p><p><b>METHODS</b>Polyethyleneglycol (PEG) was coupled to polyethylenimine (PEI 600) and platinum tetrachloride; PEG-PEI-Pt complex was formed in ethanol. The complex was characterized by XRD, UV-VIS and FT-IR and the DNA condensation was tested by electrophoretic mobility shift assay. The cell viability was evaluated by MTT assay in Hela, B16, A293 and COS-7 cells and in vitro transfection efficiency was measured in A293 and B16 cells.</p><p><b>RESULT</b>The structure of PEG-PEI-Pt was characterized by XRD, UV-VIS and FT-IR. PEG-PEI-Pt complex was able to bind DNA at N/P weight ratio of 0.4:1; the complex showed cytotoxicity on Hela and B16 cells. The complex had higher transfection efficiency in A293 and B16 cells than PEI 600.</p><p><b>CONCLUSION</b>A novel drug carrier and gene vector PEG-PEI-Pt was constructed successfully.</p>

Peptide CY11 conjugated polyethylenimine-beta-cyclodextrin for gene delivery / 浙江大学学报·医学版

<p><b>OBJECTIVE</b>To develop a novel non-viral gene delivery vector CY11-PEI-beta-CyD and to test its gene transfection efficiency.</p><p><b>METHODS</b>CY11 (CGMQLPLATWY) was conjugated to polyethylenimine-beta-cyclodextrin to form CY11-PEI-beta-CyD with a cross-linker [N-succinimidy-3-(2-pyridyldithio) propionate, SPDP]. (1)H-NMR and TGA were used to confirm the structure of vector. The DNA condensing ability of CY11-PEI-beta-CyD was investigated by gel retardation assay. Cytotoxicity of CY11-PEI-beta-CyD was determined by MTT assay and transfection efficiency was investigated in COS-7, Hela and B16 cells.</p><p><b>RESULT</b>CY11 was conjugated onto PEI-beta-CyD successfully, confirmed by(1)H NMR and TGA. The novel vector effectively condensed DNA at N/P ratio of 4îIt showed low cytotoxicity up to the concentration was 160 Mgr;g/ml. The transfection efficiency was 17-fold higher than that of PEI 25 kDa at N/P ratio of 20.</p><p><b>CONCLUSION</b>The novel vector CY11 -PEI-beta-CyD with low cytotoxic and high transfection efficiency may be used as a potential carrier for gene delivery.</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>