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81.
A simple hydrophilic-interaction chromatography (HILIC) method was developed for the identification and quantification of 14 nucleosides and nucleobases, namely cytosine, uracil, cytidine, guanine, hypoxanthine, xanthine, uridine, thymine, inosine, guanosine, thymidine, 2′-deoxyadenosine, 2′-deoxyinosine and 2′-deoxyuridine in two traditional Chinese medicines, Geosaurus and Leech. The separation was achieved on a TSKgel Amide-80 column (150 mm × 2.0 mm, 3.0 μm) with a mixture of acetonitrile and 10 mM aqueous ammonium acetate as the mobile phase at a flow rate of 0.2 mL/min. The temperature was set at 30 °C and UV detection wavelength was set at 260 nm. All calibration curves showed good linearity (R2 > 0.9957) within the test ranges. The overall intra- and inter-day RSD ranged from 0.4 to 3.4% and from 0.7 to 3.3%, respectively. The LOD and LOQ were in the range of 0.07-30.49 ng/mL and 0.26-60.98 ng/mL, respectively. The repeatability of the method was in the range of 2.2-5.8% for Geosaurus and 1.4-5.5% for Leech. The recoveries of the samples were in the range of 91.4-100.9% for Geosaurus, and 91.9-99.3% for Leech. The established method was applied successfully for the analysis of nucleosides and nucleobases in 22 commercially available samples collected from different regions in China and Japan. Our data showed that HILIC had advantages as a useful tool for the study of the bioactive components in Geosaurus and Leech as well as their quality control, and could therefore be used for the determination of the analytes in pharmaceutical products and biological fluids. 相似文献
82.
以廉价的异香草醛和2,4,6-三羟基苯乙酮为起始原料,经过C-异戊烯基化、选择性甲基化、甲氧甲基化、羟醛缩合、去保护基、催化环化以及脱除甲基等步骤,分别以13.3%和23%的总收率首次完成了天然异戊烯基黄烷酮Glovanon(1)和5-O-methylglovanon(2)的全合成.合成的关键步骤是2,4,6-三羟基苯乙酮的单C-异戊烯基化.所有新化合物的结构都经过1H NMR,IR,MS确认.抑菌活性研究表明,两种新合成的化合物对藤黄微球菌(M.luteus)和大肠杆菌(E.coli)均有良好的抑制作用. 相似文献
83.
Interferons (IFNs) are involved in the pathogenesis and recovery of viral and other infectious diseases. Recombinant IFNs
have been used as anti-infectious agents exhibiting a broad range of antiviral and immunomodulatory properties in both human
and domestic animals. In this report, we describe a highly efficient and economical approach to purify porcine IFN alpha (PoIFNα)
using polyhydroxybutyrate (PHB) as the affinity carrier and intein for self-cleaving removal of the affinity tag. Additionally,
the conditions of protein expression and purification have been optimized. Our results suggested that culture medium containing
1.62% (w/v) of sodium lactate dramatically increases the accumulation of PHB binding protein in Escherichia coli cells. High yields of recombinant PoIFNα (30–35 mg/L, 97% purity by high-performance liquid chromatography) were obtained
using intein-mediated self-cleaving conditions using a cleavage-inducing buffer with a pH of 6.5 at 20 °C for 24–36 h. The
antiviral activity of the recovered recombinant PoIFNα was up to 1.4 × 106 IU/mg of protein ascertained using recombinant human IFNα1 as a standard. This report also demonstrates that large-scale
production of intein-mediated purification of highly pure and active recombinant PoIFNα is feasible for the purposes of experimental
studies, veterinary clinic therapeutics, and swine infectious disease control. 相似文献
84.
以感应熔炼和不同的热处理工艺制备了La4MgNi19合金, 用X射线衍射(XRD)和电化学测试系统研究了该合金的相结构和电化学性能. 结构分析表明: 当热处理工艺为900 °C+水淬时, 合金主要由CaCu5结构的LaNi5相和少量未知相组成; 当热处理工艺为900 °C退火时, 合金主要由Pr5Co19、Ce5Co9结构的(La, Mg)5Ni19相及少量CaCu5结构的LaNi5相组成. 淬火和退火后合金的电化学循环稳定性(S100)分别为49.7%及76.0%, 合金电极的电化学性能和相结构密切相关. 退火热处理有利于生成Pr5Co19、Ce5Co9型相. 在La-Mg-Ni 系储氢合金中, La4MgNi19合金电化学循环稳定性不及La3MgNi14合金. 相似文献
85.
合成了四种双(N,N′-乙基,苯基)-2,3-萘-二(氧杂乙酰胺)(L=C30H30N2O4)稀土配合物。通过元素分析、红外光谱、差热-热重及摩尔电导值的分析,确定配合物的组成为[RE(pic)3L],RE=Eu(Ⅲ),Tb(Ⅲ),Ce(Ⅲ),Y(Ⅲ)。电化学实验表明:配体无电化学活性,配合物则呈现出一准可逆的氧化还原过程,在10~1000 mV.s-1扫速范围内配合物的氧化还原峰电流与扫描速度的平方根(ν1/2)呈良好的线性关系,表明其在玻碳电极(GCE)上的伏安行为受扩散控制。另外,通过循环伏安法、光谱法及粘度法研究了配合物与DNA的作用方式,结果表明:配合物均以插入方式与DNA作用,并且作用大小次序是Ce(pic)3L>Tb(pic)3L>Y(pic)3L>Eu(pic)3L。在pH=3.0适宜酸度条件下,建立了以Ce(pic)3L为探针定量测定DNA的分析方法。 相似文献
86.
A facile approach for the first total synthesis of two naturally occurring geranylated flavonoids, (±)‐puyanin ( 1 ) and (±)‐4′‐O‐methylbonannione ( 2 ) has been obtained with total yields of 27% and 17.8%, respectively. The key steps were regioselective cyclization of geranylated trihydroxychalcone and regioselective geranylation of 2,4,6‐trihydroxyacetophenone. 相似文献
87.
88.
89.
运用循环伏安法(CV)、计时电流法(CA)和计时电量法(CC)研究了延胡索酸泰妙菌素(Tiamulin fumarate,TF)在碳糊电极(Carbon Paste Electrode,CPE)上的电化学及其电化学动力学性质。结果表明,TF在CPE上的电化学过程是一不可逆的氧化过程,氧化峰电位Ep为0.772 V。在扫描速度10~1 000 mV.s-1范围内,其氧化峰电流Ip与扫描速度v呈良好的线性关系,表明TF在CPE上的伏安行为是一受吸附控制的过程。方波伏安(SWV)法结果表明TF氧化峰电流与其浓度在5.0×10-7~1.0×10-5mol.L-1及1.0×10-5~1.0×10-4mol.L-1范围内均呈良好的线性关系,相关系数r分别为0.9980及0.9966,检出限(S/N=3)为5.8×10-8mol.L-1,相对标准偏差(RSD)为0.8%~2.8%,加样回收率为97.6%~102.0%。据此建立了TF含量的电化学测定方法。该方法简便快捷,测定结果令人满意。 相似文献
90.