Fatty acid synthase inhibitors of phenolic constituents isolated from Garcinia mangostana

Natural inhibitors of fatty acid synthase (FAS) are emerging as potential therapeutic agents to treat cancer and obesity. The bioassay-guided chemical investigation of the hulls of Garcinia mangostana led to the isolation of 13 phenolic compounds (1–13) mainly including xanthone and benzophenone, in which compounds 7, 8, 9, 10, and 11 were isolated from this plant for the first time and compound 9 was a new natural product. These isolates possess strong inhibitory activity of FAS with the IC₅₀ values ranging from 1.24 to 91.07 μM. The study indicates that two types of natural products, xanthones and benzophenones, could be considered as promising FAS inhibitors.     

Immunohistochemical localization of LIM mineralization protein 1 during mouse molar development

LIM mineralization protein 1 (LMP-1) is an essential positive regulator of osteoblast differentiation, maturation and bone formation. Our previous investigations on the distribution of LMP-1 in mature human teeth indicated that LMP-1 might play a role in the odontoblast differentiation and dentin matrix mineralization. The aim of the present study was to use immunohistochemistry to determine the expression of LMP-1 during tooth development in mouse molars. In embryonic and postnatal Kunming mice, LMP-1 protein was expressed during molar development, but the expression levels and patterns differed at various developmental stages. At embryonic day 13.5 (E13.5), LMP-1 was found in the enamel organ. At E14.5, LMP-1 was detected in the entire enamel organ and in the underlying mesenchyme. At E16.5, LMP-1 was observed in the inner and outer enamel epithelium and the stratum intermedium. The expression also converged at the cusps in the dental papilla. At E18.5 and postnatal day 2.5 (P2.5), LMP-1 was restricted to the stratum intermedium, in differentiating dental papilla cells at cusps, while it disappeared in terminal differentiated ameloblasts and odontoblasts. At P13.5, no positive staining was detected in the odontoblasts or in the dental pulp cells. Therefore, LMP-1 showed spatiotemporal expression patterns during molar development and might participate in molar crown morphogenesis and odontoblast differentiation at late molar development.     

Analysis of cyclosporine A and its metabolites in rat urine and feces by liquid chromatography–tandem mass spectrometry

A sensitive and specific liquid chromatography–tandem mass spectrometry (LC–MS/MS) method was developed and validated for the quantification of cyclosporine A (CyA) and the identification of its metabolites in rat urine and feces. The analytes were extracted from waste samples via liquid–liquid extraction. A Turboionspray source was used as a detector. It was operated in a positive ion mode with transitions of m/z 1225 → m/z 1112 for CyA and in a selected multiple reactions monitoring (MRM) mode with transitions of m/z 1239 → m/z 1099 for the internal standard (cyclosporine D, CyD). Linear calibration curves were obtained for CyA concentration ranges of 12.5–250 ng mL^?1 in urine and 2.5–375 ng mg^?1 in feces. The intra- and inter-day precision values (relative standard deviation) obtained were less than 8%, and the accuracy was within ±15% for each of the analytes. Extraction recoveries of CyA and CyD were both over 80%. The identification of the metabolites and elucidation of their structure were performed on the basis of their retention times and mass spectrometry fragmentation behaviors. A total of seven metabolites in rat feces were identified as dimethyl CyA, hydroxy CyA, and dihydroxy CyA after the oral administration of cyclosporine A-Eudragit^® S100 nanoparticles (CyA-NP). Six of these metabolites were also detected in rat urine. A possible metabolic pathway was also proposed. The newly developed method was proven to be sensitive, simple, reproducible, and suitable for the rapid determination of CyA. It was successfully employed to study the excretion of CyA in rats and could be used to better understand the in vivo metabolism of CyA-NP, a potentially effective nanoparticle system.     

Proteomic analysis of symbiosome membranes in Cnidaria–dinoflagellate endosymbiosis

Symbiosomes are specific intracellular membrane‐bound vacuoles containing microalgae in a mutualistic Cnidaria (host)–dinoflagellate (symbiont) association. The symbiosome membrane is originally derived from host plasma membranes during phagocytosis of the symbiont; however, its molecular components and functions are not clear. In order to investigate the protein components of the symbiosome membranes, homogenous symbiosomes were isolated from the sea anemone Aiptasia pulchella and their purities and membrane intactness examined by Western blot analysis for host contaminants and microscopic analysis using various fluorescent probes, respectively. Pure and intact symbiosomes were then subjected to biotinylation by a cell impermeant agent (Biotin‐XX sulfosuccinimidyl ester) to label membrane surface proteins. The biotinylated proteins, both Triton X‐100 soluble and insoluble fractions, were subjected to 2‐D SDS‐PAGE and identified by MS using an LC‐nano‐ESI‐MS/MS. A total of 17 proteins were identified. Based on their different subcellular origins and functional categories, it indicates that symbiosome membranes serve as the interface for interaction between host and symbiont by fulfilling several crucial cellular functions such as those of membrane receptors/cell recognition, cytoskeletal remodeling, ATP synthesis/proton homeostasis, transporters, stress responses/chaperones, and anti‐apoptosis. The results of proteomic analysis not only indicate the molecular identity of the symbiosome membrane, but also provide insight into the possible role of symbiosome membranes during the endosymbiotic association.     

美国生物质资源研究规划与举措分析及启示

发展生物质资源研究对于国家的可持续发展具有重要的战略意义。近年来,美国相继制订若干研究计划或发展路线图,并采取有效举措,持续推动生物质资源的研究、开发和利用。通过分析美国在生物质资源研究领域的重要举措,特别是分析其相关重要规划的具体内容,总结生物质资源研究面临的重要问题和研究热点,对发展我国生物质资源研究提出一些思考建议。