A method based on ultra-performance liquid chromatography mass spectrometry (UPLC-MS) applying atmospheric pressure chemical ionization in the positive ion mode is developed for the determination of coenzyme Q10 (CoQ10) in rat urine. The assay involves the extraction of crude urine, fast liquid chromatography on a Waters Acquity UPLC BEH C18 column (1.7 microm, 1.0 x 50 mm), and selected ion monitoring detection using mass transition. The calibration range is found to be 0.05-25 microg/mL, with the lower limit of quantitation of 0.05 microg/mL. Intra- and inter-day precision (relative standard deviation) for CoQ10 in rat urine range from 0.7% to 15%, and accuracy expressed in recovery rates in urine is between 83% and 118%. The recovery of this method is found to be between 80% and 95% at three concentrations. The total cumulative recovery of CoQ10 is 1.16 +/- 1.05% (percentage of dose intake, n = 4) from rat urine collected over 30 h after oral administration of the drug. The UPLC-MS method described allows the quick determination of CoQ10 in rat urine with good precision and accuracy. It is suitable for further excretion studies of CoQ10 in animals. 相似文献
Three new highly oxygenated nortriterpenoids, wilsonianadilactones A–C ( 1 – 3 ), together with twelve known ones, i.e., 4 – 15 , were isolated from the leaves and stems of Schisandra wilsoniana. Their structures were established by means of extensive analysis of spectroscopic data, and compound 1 was further confirmed by X‐ray crystallographic diffraction. Compounds 1 – 3 showed weak anti‐HIV‐1 activity with EC50 values of 23.5, 55.5, and 66.4 μg/ml, respectively. 相似文献
N,N,N-Trimethylchitosan chloride with different degrees of quaternization has been synthesized and characterized by (1)H NMR spectroscopy. The particle size ranges from 150 to 600 nm, which is dependent on the N/P ratio and is less influenced by the degree of quaternization. The majority of the particles have a spherical morphology. The zeta potential of the particles increases with the N/P ratio and the quaternization degree of TMC. Short-term contact experiments show good biocompatibility of TMC, but long-term contact experiments reveal its high toxicity. This study suggests that TMC is a promising gene carrier, but further modification is still required to improve its cytocompatibility. 相似文献
Emulsion copolymerization of poly(methacrylic acid) and poly(2-(diethylamino)ethyl methacrylate) (PMAA/PDEA) yielded pH-responsive polyampholyte microgels of 200-300 nm in diameter. These microgels showed enhanced hydrophilic behavior in aqueous medium at low and high pH, but formed large aggregates of approximately 2500 nm at intermediate pH. To achieve colloidal stability at intermediate pH, a second batch of microgels of identical monomer composition were synthesized, where monomethoxy-capped poly(ethylene glycol)methacrylate (PEGMA) was grafted onto the surface of these particles. Dynamic light-scattering measurements showed that the hydrodynamic radius, Rh, of sterically stabilized microgels was approximately 100 nm at intermediate pH and increased to 120 and 200 nm at pH 2 and 10, respectively. Between pH 4 and 6, these microgels possessed mobility close to zero and a negative second virial coefficient, A2, due to overall charge neutralization near the isoelectric pH. From the Rh, mobility, and A2, cross-linked MAA-DEA microgels with and without PEGMA retained their polyampholytic properties in solution. By varying the composition of MAA and DEA in the microgel, it is possible to vary the isoelectric point of the colloidal particles. These new microgels are being explored for use in the delivery of DNA and proteins. 相似文献
Summary: A probability model, based on the “in‐out” recursive analysis, is developed for obtaining the average molecular weights of star polymers formed by connecting polydispersed primary chains onto a multifunctional coupling agent. The average properties and the polydispersity index of the formed star polymers can be described as a function of the reaction conversion and the average properties of the polydispersed primary chains without the knowledge of the whole distribution. The results indicate that, although PI of the resulting star polymers might increase at the intermediate conversion for the higher functionalities of the core molecules, the resulting star polymers generally have narrower molecular weight distributions at the complete conversion compared to the initial polydispersed polymer chains.
A schematic illustration of the star polymer formation. 相似文献