Asymmetric synthesis of ceramide sphingolipid based on (2S,3S,4S)-3,4-dihydroxy-5-(hydroxymethyl)pyrrolidine lactam

A facile approach to the versatile chiral building block 2 was developed based on glutamic acid, whereby a new method for asymmetric synthesis of sex pheromone 1 was explored from cheap glutamic acid.     

肉芝软珊瑚Sarcophyton sp中次生代谢产物的研究

从中国海南岛三亚附近海域采集的肉芝软珊瑚Sarcophyton sp中,分离得5个结晶化合物。通过化学和波谱方法鉴定出他们的结构分别是：24亚甲基胆甾-1α,3β,5α,6β-四醇(1);24-亚甲基胆甾14-烯-3β,6β-二醇(2);2．十六碳酰胺基-十八-4(E),8(E)-二烯-1,3-二醇(3);(2S,3S,5R)-2-十六碳酰胺基-十八-1,3,5-三醇(4);柳珊瑚甾醇(5)。生理活性试验表明,化合物1对人体鼻咽癌(CNE2)和胃癌(NGC-803)细胞有强抑制活性;化合物2对P-388肿瘤细胞有强抑制活性;柳珊瑚甾醇(5)有明显的抗心律失常和减慢心率等作用。     

Production of ceramide with Saccharomyces cerevisiae

The possibility of producing the biologically active material of the skin, ceramide, was studied using yeasts. The yeast strain that produced the most ceramide, Saccharomyces cerevisiae (KCCM 50515), was selected, and the optimal conditions for ceramide production were determined using shakeflask culture and batch fermentation. By measuring the production rate of ceramide at various pH values and temperatures, the optimal conditions for ceramide production were found to be pH 6.0 and 30°C. When heat shock was applied to the cells for 1 h by increasing the culture temperature from 30 to 40°C after cell growth, the amount of ceramide produced was increased 5.9-fold. A cell growth and ceramide production model was developed with Monod kinetics and the Leudecking-Piret model. It showed that ceramide production was increased when the cells were in the stationary phase.     

Application of a xenon arc lamp as a light source for evaporative light scattering detection

The standard tungsten-halogen light source used in a commercial evaporative light scattering detector (ELSD) was replaced with a 180 W xenon arc lamp. The xenon arc lamp possesses a broader spectrum in the UV region than the halogen source. The influence of the UV transmittance of five selected solvents was studied with a size-exclusion chromatography column. This solvent parameter was not observed to influence the ELSD response between the two light source settings. With the solvents studied, better sensitivity was obtained with the xenon arc lamp than the halogen lamp. This high-energy source was applied to ceramide III analysis with an octadecyl-grafted silica column and methanol:tetrahydrofuran 97:3 as the mobile phase, and the sensitivity of the quantification of ceramide III increased 16-fold for injected amounts of 14∼140 ng. The molecular species in a sample of naturally occurring ceramides was analyzed using two C18 columns at 40 °C and gradient elution from 100% acetonitrile to 100% isopropanol in 30 min. The increased ELSD sensitivity achieved when using the xenon arc lamp allowed both the minor and major ceramide species to be observed, in contrast to the results achieved when the halogen lamp was used, where the increased photomultiplier voltage needed to observed the signals from the minor species caused the signals from the major ceramide species to occur above the detector response window.     

Design and synthesis of caged ceramide: UV-responsive ceramide releasing system based on UV-induced amide bond cleavage followed by O-N acyl transfer

Sphingolipids, recognized as membrane constructs and as key signaling molecules, have been studied to examine intracellular function. Some caged sphingolipids that release parent sphingolipids after exposure to UV-irradiation have been previously developed, but caged ceramide has yet to be reported. In this study, we report the design and synthesis of a caged ceramide. Photo-irradiation experiment clarified that the caged ceramide can be successfully converted to the parent ceramide by UV-irradiation. Introduction of an alkyne-handle moiety for further modification of the caged ceramide is also reported.     

Scanning electron microscopy study on nanoemulsions and solid lipid nanoparticles containing high amounts of ceramides

Ceramides are the most important intercellular lipids of the stratum corneum, regulating the barrier function of the skin and participating as second signal messenger in stress-induced apoptosis. The high lipophilicity of ceramides presents a pharmacological problem. In order to overcome this problem two lipophilic delivery systems were used for the incorporation of the ceramides: (1) nanoemulsions (NE) and (2) solid lipid nanoparticles (SLN). The influence of the incorporation of ceramides on the particle shape, size and Polydispersity Index was investigated by photon correlation spectroscopy (PCS) and scanning electron microscopy (SEM). The results showed that NE can incorporate larger amounts of ceramides than SLN (up to 23.2% and 5% of lipid matrix, respectively) without any significant alteration on the morphology of the dispersed particles. The incorporation of higher amounts of ceramides into SLN, leads to anisometric platelet-like formations that are known to be caused by the transition of triglycerides from - to β-mesomorph. The results of this study can be useful for the design of appropriate delivery systems and for further pharmacological evaluations.     

Synthesis and biological evaluation of aziridine-containing analogs of phytosphingosine

Six new aziridine-containing analogs of phytosphingosine designed as constrained anhydrophytosphingosine were synthesized. The synthetic route developed also afforded an access to an original bicyclic analog of the natural anhydrophytosphingosine jaspine B. All these new compounds were evaluated for their capacities to affect melanoma cell viability.     

神经鞘磷脂合成酶基因沉默对细胞凋亡的影响

以HEK293细胞为模型, 利用RNA干扰技术, 将神经鞘磷脂合成酶(SMS)的同工酶(SMS1和SMS2)的siRNA分别联合、转染HEK293细胞. 通过薄层层析法评价SMS酶活性, 同时测神经酰胺(Cer)、卵磷脂(PC)及神经鞘磷脂(SM)的水平, 并以流式细胞仪和Annexin V-FITC、PI双染法检测细胞凋亡. 结果显示, 与对照组相比, SMS基因沉默后SMS表达水平降低(分别降低17%, 20%, 49%); SM水平显著性降低(P<0.05); Cer水平显著性升高(P<0.05); TNF-α诱导的凋亡显著性升高[分别为58%(P<0.01), 24%(P<0.05), 77%(P<0.01)]. 这些结果提示, SMS基因沉默能降低SM水平并升高Cer水平, 明显增加TNF-α诱导的HEK293细胞凋亡. 由于SM是动脉粥样硬化形成的独立危险因子, 因此本研究有可能为动脉粥样硬化的治疗找到新的靶点和有效途径.