Metabolite Identification of Myricetin in Rats Using HPLC Coupled with ESI-MS

Myricetin, a naturally occurring flavonol, shows multifarious pharmacological activities, e.g., antidiabetic, antioxidant, anti-inflammatory, antitumor, and liver protection effects. In order to obtain an understanding of the myricetin’s metabolism in vivo, a rapid and sensitive method by high-performance liquid chromatography coupled with electrospray-ionization mass spectrometry (HPLC-MSⁿ) techniques was employed to investigate the biotransformation in rats after oral administration of myricetin. Recognition and structural exposition of the metabolites were operated by comparing the changes in molecular mass (ΔM) and MSⁿ spectra with the parent drug. As a result, the parent compound and seven metabolites were found in rat plasma, urine, and feces. In addition, besides 3,5-dihydroxyphenylacetic acid (M1) and 3,4,5-trihydroxyphenylacetic acid (M2), five other compounds were first discovered in the metabolite research of myricetin. These results indicated that, besides ring-fission, there were methylate (M3, M4, M5) and glucuronide (M6, M7) biotransformations of myricetin occurring in vivo.

     

开放光程扬尘颗粒物浓度测量方法及系统

利用单波长激光通过扬尘空间发生散射消光衰减的特性,设计了开放光程的颗粒物浓度检测方法及系统。该方法利用双峰正态分布模型模拟颗粒物粒径分布,实时计算一定空间范围内的扬尘颗粒物浓度,具有响应速度快、测量动态范围宽的优点,适合浓度高、变化快、空间范围大的扬尘颗粒物浓度测量。通过水溶胶模拟实验与烟尘实验验证了该方法的可行性。实验数据表明,系统量程可达0~400mg/m3,分辨率为0.05mg/m3,响应时间小于1s。     

A novel caged-prenylxanthone from Garcinia bracteata

<正>A novel caged-prenylxanthone xanthone,neobractatin(1),was isolated from the twig of Garcinia bracteata.Its structure was elucidated by spectroscopic methods,especially 2D NMR techniques.     

Expression and Characterization of an Active Chimeric Protein of Human Extracellular Superoxide Dismutase and hCuZnSOD in Pichiapastoris

Mammalian cells express two isoforms of Cu-and Zn-containing superoxide dismutases(SODs),CuZnSOD and extracellular SOD(EC-SOD),involved in the defense system against reactive oxygen species(ROS).The two SODs have structurally homologous centre domain with distinct N-and C-terminuses,resulting in the different characteristics of the structure and function of the two molecules.We generated a hybrid SOD molecule(namely hySOD) via replacing the N-and C-terminuses of hCuZnSOD with the counterparts of hEC-SOD.The...     

Complete Quenching of the Pd3(dppm)3(CO)2+ Cluster Emission Via Electrostatic Host–Guest Assemblies with Carboxylate-Containing Tetraphenylporphyrins of Ni(II) and Fe(III)

The title cluster is luminescent at 77?K and exhibits an unsaturated site for binding anions when the counter ion is PF₆ ^?. A series of five non-luminescent metalloporphyrins exhibiting carboxylate anchoring groups were synthesized and characterized. These are the sodium salts of the 5-carboxyphenyl-tri-10,15,20-tolyl-, trans-di-5,10-carboxyphenyl-di-15,20-tolyl-, and tetra-5,10,15,20-carboxyphenyl(metallo)porphyrin (metallo?=?chloroiron(III), nickel(II)) anions. Evidence for supramolecular assemblies between the carboxylates and the cluster is provided by ³¹P NMR and UV?Cvis spectroscopy. The binding constant, K_1n, extracted from the UV?Cvis data via Benesi-Hildebrand, Scott and Scatchard plots are approximately 21,000?±?5,000?M^?1 for the nickel(II) species, in agreement with the previously reported zinc(II) ones (K₁₁?=?20,000?±?2,000?M^?1), but those for the chloroiron(III) are measured to be lower (12,500?±?3,500?M^?1). This association is accompanied by a complete quenching of the luminescence of the cluster which can only be due to an efficient energy transfer to the d?Cd states of the chloroiron(III) and nickel(II) species but an electron transfer from the nickel(II)-containing chromophore to the cluster is also possible. This work demonstrates the profound effect that supramolecular interactions may have on the photophysical properties despite the long donor?Cacceptor separation.     

Effects of source opacity and expansion on two-pion Bose-Einstein correlations

We examine two-pion Bose-Einstein correlations for partially coherent particle-emitting sources within quantum statistical formalism, where the sources are treated as classical currents with chaotic and coherent components. The two-pion correlation functions of the partially coherent sources contain a phase which is sensitive to the asymmetry of the source emission function. We investigate the influence of source opacity and expansion in high energy heavy ion collisions on the phase by Monte Carlo calculati...