Space Group of Aquaimidazolemaleatozinc, [(H2O)(C3H4N2)(O2CCH=CHCO2Zn)]n

The space group of [(H2O)(C3H4N2)(O2CCH=CHCO2Zn)]n, which was originally described in the acentric Pc space group (Liu et al., Chin. J. Struct. Chem. 2004, 23, 160～163), is re-described in the centric P21/c space group.The crystal structure of (H2O)(C3H4N2)O2C-CH=CHCO2Zn was refined in the acentric Pc space group on 266 variables to R = 0.037 for the 1926 of the 2067 obeying the I > 2σ criterion[1]. The structure is better described in the centric P21/c space group (Table 1) as the two indepen-dent formula units are related by a center of symmetry. The 21 screw axis is must be pre-sent, as noted from the systematically absent 0k0 (k = 2n + 1) reflections in the 3302 reflections that were simulated[2, 3] from the published cell dimensions and atomic coordinates. Crystallo-graphica[4] estimates the hemisphere of reflections to be 3302, so that only a little more than the minimum monoclinic data must have been collec-ted in the study. A revision from Pc to P21/c is not particularly common[5] as the P21/c space group is uniquely determined from systematic absences. The polymeric chain propagates linearly along the c-axis of the unit cell (Fig. 1).     

Dynamic Structural Transformation of Resveratrol‐Modified Stearate Liposomes Led to a Spontaneous Drug Release System

A mono‐substituted resveratrol derivative, resveratrol‐modified stearate (RMS), was synthesized by selectively coupling of stearic acid to the monohroxyphenyl of resveratrol in order to enhance both the stability and bioavailability of resveratrol. The RMS self‐assembles into liposomes and a series of suprastructural transformations into metastable helical ribbon, linear wire‐like structures, and inert spherical nanoparticles were detected that may be induced by the hydrogen‐bonding interactions. As a model for drug‐release investigations, gold nanoparticles (AuNPs) were encapsulated successfully by RMS to generate vesicles and succeed to release AuNPs druing the transformation to a ribbon‐like metastable stucture at ambient temperature.     

Preparation of electroactive silica mesopores by encapsulating polyaniline chains into silica framework via nonsurfactant templating sol-gel route

Electroactive silica mesopores have been synthesized by encapsulating different loadings of polyaniline chains into a silica network through sol-gel reactions of TEOS in the presence of polyaniline latex with D-glucose. It should be noted that the electroactive silica mesopores at higher polyaniline loading was found to reveal higher surface areas, larger pore volume, and slightly larger pore diameters as compared to that of neat non-electroactive silica mesopores.     

Pseudoalteromone A: a novel bioactive ubiquinone from a marine bacterium Pseudoalteromonas sp. CGH2XX (Pseudoalteromonadaceae)

A novel ubiquinone derivative, pseudoalteromone A (1), possessing a 9C nor-monoterpenoid moiety was produced from a marine bacterium Pseudoalteromonas sp. CGH2XX. This bacterium is originally isolated from a cultured-type octocoral Lobophytum crassum. The structure of ubiquinone 1 was established by spectroscopic methods. Pseudoalteromone A (1) exhibited significant cytotoxicity toward the MOLT-4 (human acute lymphoblastic leukemia, IC₅₀ = 3.764 μg/mL) cells and displayed a significant inhibitory effect (inhibition rate 45.1%) on the release of elastase by human neutrophils at a concentration of 10 μg/mL.     

Determination of metformin in rat plasma by HILIC-MS/MS combined with Tecan automation and direct injection

Metformin is a well‐known oral antihyperglycemic drug used in treatment of type II diabetes. Analysis of metformin in biological fluids is a challenge owing to its high polarity and small molecular size, which lead to poor retention of metformin on reversed‐phase liquid chromatographic columns. A high‐throughput method was developed and validated for the determination of metformin in rat plasma in support of preclinical toxicology studies, using hydrophilic interaction liquid chromatography tandem mass spectrometry (HILIC‐MS/MS) and Tecan automated sample preparation. Extracted samples were directly injected onto the unbounded silica column with an aqueous–organic mobile phase. This HILIC‐MS/MS method was validated for accuracy, precision, sensitivity, stability, matrix effect, recovery and calibration range. Acceptable intra‐run and inter‐run assay precision (coefficient of variation ≤ 3.9%) and accuracy (99.0–101.8%) were achieved over a linear range of 50–50,000 ng/mL. Metformin is stable in rat plasma for at least 6 h at room temperature, 147 days at ?70°C and through three freeze (?70°C) and thaw cycles. Metformin is also stable in rat whole blood for at least 2 h at room temperature and in an ice–water bath. The validated method was successfully used in support of several preclinical studies where metformin is dosed together with an investigational drug substance. The ruggedness of the validated method was demonstrated by the incurred sample reproducibility test. Copyright © 2011 John Wiley & Sons, Ltd.