软珊瑚Sinularia sp.中次生代谢产物的结构鉴定

细胞毒性;软珊瑚Sinularia sp.中次生代谢产物的结构鉴定     

Liquid Chromatographic Analysis of Arabinosylcytosin and 1-β-D-Arabinofuranosyluracil in Treatment with Cyclophosphamide and Pirarubicin

A reversed-phase liquid chromatographic (RPLC) method has been developed for determination of arabinosylcytosin (Ara-C) and its metabolite 1-β-D-arabinofuranosyluracil (Ara-U) on a 250 mm × 4.6 mm i.d., 5 μm particle, Diamonsil C₁₈ column. The mobile phase was a mixture of 5% methanol and 95% 10 mmol L⁻¹ phosphate buffer adjusted to pH 5.5. The flow-rate was 1.0 mL min⁻¹ and the injection volume 20 μL. Eluting compounds were detected at 270 nm by use of an ultraviolet detector. Under these LC conditions cyclophosphamide (CTX) and pirarubicin (THP), two other medicines given with Ara-C in clinical treatment, do not interfere with measurement of Ara-C and Ara-U. Individual calibration plots of peak area against concentration generated from analysis of standard solutions were used to calculate the concentrations of Ara-C and Ara-U in sample solutions. The calibration plot was linear in the range 2.5–100 μg mL⁻¹, the average recovery of Ara-C and Ara-U was more than 98% (RSD < 2.5%), and between-day and within-day precision, expressed as relative standard deviation (RSD), were below 4.0%. LOQ for both Ara-C and Ara-U was 2 μg mL⁻¹. The method is rapid, simple, accurate and reproducible, and especially useful for application to patient samples.     

Effect of the medium pH on the release of secondary metabolites from roots ofDatura stramonium,Catharanthus roseus,andTagetes patula cultured in vitro

The release of alkaloids from root culturesDatura stramonium andCatharanthus roseus and thiophenes from root cultures ofTagetes patula was found to increase when the pH of the culture media (ranging from 4.8 to 7.0) was reduced to 3.5. The extent of the effect was different in each type of culture. Increases ranged from 4- to 20-fold, which in some cases accounted for 75% of the total secondary metabolite pool produced per flask. When the release of individual metabolites was measured, even larger increases, were observed (nearly 400-fold for ajmalicine). Increased release of alkaloids fromC. roseus roots were also observed in cultures growing in a 14-L fermentor, when the medium pH was reduced. Reduction of the pH of the media did not affect growth of the root cultures in subsequent subcultures. The importance of this treatment as a stategy to improve the recovery of secondary metabolites from producing cultures is discussed.     

Biochemical reaction engineering for redox reactions

Redox reactions are still a challenge for biochemical engineers. A personal view for the development of this field is given. Cofactor regeneration was an obstacle for quite some time. The first technical breakthrough was achieved with the system formate/formate dehydrogenase for the regeneration of NADH2. In cases where the same enzyme could be used for chiral reduction as well as for cofactor regeneration, isopropanol as a hydrogen source proved to be beneficial. The coproduct (acetone) can be removed by pervaporation. Whole-cell reductions (often yeast reductions) can also be used. By proper biochemical reaction engineering, it is possible to apply these systems in a continuous way. By cloning a formate dehydrogenase and an oxidoreductase "designer bug" can be obtained where formate is used instead of glucose as the hydrogen source. Complex sequences of redox reactions can be established by pathway engineering with a focus on gene overexpression or with a focus on establishing non-natural pathways. The success of pathway engineering can be controlled by measuring cytosolic metabolite concentrations. The optimal exploitation of such systems calls for the integrated cooperation of classical and molecular biochemical engineering.     

Terreinol--a novel metabolite from Aspergillus terreus: structure and C labeling

A novel metabolite from Aspergillus terreus, named terreinol, was isolated and its biosynthetic origin was determined by NMR based on the incorporation of [1-¹³C]-d-glucose. The labeling pattern indicated a predominant polyketide biosynthetic origin for this metabolite.     

Comparative bioanalytical study of3H-deramciclane in dog plasma, using a gas chromatography-nitrogen-selective detection (GC-NPD), a new GC-radiochemical detection (GC-RD) and a liquid scintillation method

Summary A new, highly sensitive and selective gas chromatography method, using radiochemical detection (GC-DR) was developed for the selective determination of³H-labelled deramciclane and its N-desmethyl metabolite in dog plasma. Inter-day accuracy and precision, as well as system suitability of the GC-RD method was investigated during the method validation. The calibration curve was proved to be linear (r=0.9986) in a wide concentration range (13–1000 ngeqv mL⁻¹) The lower limit of quantitation (LLOQ) was 13.7 ngeqv mL⁻¹, and the limit of the detection (LOD) was 1 ngeqv mL⁻¹. Using this new GC-RD method, plasma levels of³H-labelled deramciclane and its metabolite were determined in dogs, after the administration of a single 10 mg kg⁻¹ oral dose. Pharmacokinetic curves and the calculated pharmacokinetic parameters were compared to those obtained using a previously elaborated gas chromatography-nitrogen selective detection method (GC-NPD) and to those obtained by measuring the plasma level of total radioactivity (liquid scintillation counting, LSC). Pharmacokinetic curves and the calculated pharmacokinetic parameters obtained with the two different gas chromatography detection methods (NPD and RD) showed good correlation. Comparison of these results to those acquired by total radioactivity measurement demonstrated that deramciclane was intensively metabolised. Moreover, the biological half-life (t ₁ ^2/β ) of the unknown metabolites proved to be more than a magnitude longer than the half-life of the parent compound or that of N-desmethyl metabolite. Presented at: Balaton Symposium on High-Performance Separation Methods, Siófok, Hungary, September 3–5, 1997.     

不同生境对银杏雌、雄株嫁接苗叶中聚戊烯醇等成分积累的影响

【目的】探究生境对银杏(Ginkgo biloba)叶中聚戊烯醇、可溶性糖、可溶性蛋白和类脂4类代谢产物积累的影响,探索影响代谢产物积累的主要立地因子,为银杏栽培提供理论依据。【方法】采用随机区组试验设计,方差分析、多重比较、相关性分析和逐步回归分析等方法,研究雌株和雄株银杏在7个生境下叶中聚戊烯醇、可溶性糖、蛋白质和类脂等变化规律。【结果】来自不同生境银杏叶中聚戊烯醇、可溶性糖、蛋白质和类脂的含量存在显著差异(P<0.05),来自石家庄地区叶中聚戊烯醇、可溶性糖、可溶性蛋白和类脂的含量最高;聚戊烯醇含量与类脂含量呈极显著正相关关系(P<0.01),但与蛋白质含量呈显著负相关关系(P<0.05);平均最暖月气温是影响银杏叶中聚戊烯醇、可溶性糖、可溶性蛋白和类脂积累的关键环境因子,此外日照时长和土壤中P、K含量对其的积累也具有较大的影响。【结论】环境因素会显著影响银杏叶中代谢产物的含量,温暖的生境有助于聚戊烯醇等类脂类物质的合成与积累。     

Studies towards the total synthesis of contignasterol

The (17R,20S,22S,24S) C₂₀-C₂₉ segment of contignasterol has been stereoselectively prepared in 8 steps and 40% overall yield from (S)-carvone. Synthetic studies towards contignasterol's C/D ring functionalization/isomerization are also reported.     

Concentration profiles of cocaine, pyrolytic methyl ecgonidine and thirteen metabolites in human blood and urine: determination by gas chromatography-mass spectrometry

When cocaine is smoked, a pyrolytic product, methyl ecgonidine (anhydroecgonine methyl ester), is also consumed with the cocaine. The amount of methyl ecgonidine formed depends on the pyrolytic conditions and composition of the illicit cocaine. This procedure describes detection of cocaine and 10 metabolites--cocaethylene, nor-cocaine, nor-cocaethylene, methyl ecgonine, ethyl ecgonine, benzoylecgonine, nor-benzoylecgonine, m-hydroxybenzoylecgonine, p-hydroxybenzoylecgonine and ecgonine--in blood and urine. In addition, the detection of pyrolytic methyl ecgonidine and three metabolites--ecgonidine (anhydroecgonine), ethyl ecgonidine (anhydroecgonine ethyl ester) and nor-ecgonidine (nor-anhydroecgonine)--are included. The newly described metabolites, ethyl ecgonidine and nor-ecgonidine, were synthesized and characterized by gas chromatography-mass spectrometry (GC-MS). All 15 compounds were extracted from 3 mL of blood or urine by solid-phase extraction and identified by a GC-MS method. The overall recoveries were 49% for methyl ecgonine, 35% for ethyl ecgonine, 29% for ecgonine and more than 83% for all other drugs. The limits of detection were between 0.5 and 4.0 ng/mL except for ecgonine, which was 16 ng/mL. Linearity for each analyte was established and in all cases correlation coefficients were 0.9985-1.0000. The procedure was applied to examine the concentration profiles of analytes of interest in post-mortem (PM) blood and urine, and in urine collected from living individuals (LV). These specimens previously were shown to be positive for the cocaine metabolite, benzoylecgonine. Ecgonidine, the major metabolite of methyl ecgonidine, was present in 77% of PM and 88% of the LV specimens, indicating smoking as the major route of cocaine administration. The new pyrolytic metabolites, ethyl ecgonidine and nor-ecgonidine, were present in smaller amounts. The urine concentrations of nor-ecgonidine were 0-163 ng/mL in LV and 0-75 ng/mL in PM specimens. Ethyl ecgonidine was found only in PM urine at concentrations 0-39 ng/mL. Ethanol-related cocaine metabolites, ethyl ecgonine or cocaethylene, were present in 69% of PM and 53% of cocaine-positive LV specimens, implying alcohol consumption with cocaine use. The four major metabolites of cocaine--benzoylecgonine, ecgonine, nor-benzoylecgonine and methyl ecgonine--constituted approximately 88 and 97% of all metabolites in PM and LV specimens, respectively. The concentrations of nor-cocaine and nor-cocaethylene were consistently the lowest of all cocaine metabolites. At benzoylecgonine concentrations below 100 ng/mL, ecgonine was present at the highest concentrations. In 20 urine specimens, benzoylecgonine and ecgonine median concentrations (range) were 54 (0-47) and 418 ng/mL (95-684), respectively. Therefore, detection of ecgonine is advantageous when benzoylecgonine concentrations are below 100 ng/mL.     

中国红豆杉悬浮细胞培养动力学的研究

考察了中国红豆杉悬浮细胞培养中细胞生长的动态变化，培养基中主要营养成分的消耗，细胞的氧消耗速率，以及次级代谢产物紫杉醇的生产状况。实验结果表明，细胞比生长速率为０．１２９／ｄ，紫杉醇的积累与细胞生长呈部分相关在，培养静止期达到高峰。