Synthesis of 14-Bromo and 14-Hydroxy Baccatin III Derviatives

Several 14 alpha- and 14 beta -bromo baccatin III derivatives were synthesized by direct bromination and from silyl enol ether of 13-oxo-7-TES-baccatin III. 14 beta -Hyroxy baccatin III derivative was also obtained from the same silyl enol ether.

Interaction of N-(2-Methyl Thio Phenyl)-2-Hydroxy-1-Naphthaldimine with Tin Dioxide Nanoparticles: A Spectroscopic Approach

The interaction of N-(2-methyl thiophenyl)-2-hydroxy-1-naphthaldimine (NMTHN) with tin dioxide nanoparticles (SnO2 NPs) has been investigated by spectroscopic tools such as absorption and fluorescence spectroscopy. Absorption spectroscopy reveals the formation of ground state complex. Fluorescence spectroscopy has been used to study the signatures of fluorescence quenching. SnO2 NPs are found to quench the intrinsic fluorescence of NMTHN via static and dynamic quenching. The deviation from linearity in the Stern-Volmer plot has been observed.

云南红豆杉的化学成分研究及1-去羟基巴卡亭VI的结构修饰

目的研究云南红豆杉(Taxus yunnanensis)心木的化学成分并对1-去羟基巴卡亭VI进行了结构修饰。方法采用各种现代色谱技术进行分离纯化,根据化合物的理化性质和波谱数据进行结构鉴定。并对1-去羟基巴卡亭VI进行了选择性的去乙酰化反应。结果从云南红豆杉心木的95%乙醇提取物中分离并鉴定了7个紫杉烷类化合物。对其中一个含量较高的化合物进行了结构修饰,得到两个去乙酰化的产物,并鉴定了其结构。结论结构修饰所得到的13位去乙酰产物是我们所需要的,它为今后进一步合成符合紫杉醇构效关系的产物提供了物质基础。

红豆杉中二个新紫杉烷二萜化合物的分离与测定

从红豆杉Taxus chinensis(Pilger)Rehd。树皮中得到二个新的紫杉烷类化合物,它们的结构为1-羟基-7,9-二去乙酰基巴卡亭Ⅰ(1—hydroxy-7,9—dideacetyl—baccatin Ⅰ)和7,9-二去乙酰基巴卡亭Ⅵ(7,9-dideacetyl baccatin Ⅵ)

中国红豆杉中多种紫杉烷同时检测的液质联用方法的建立

目的:建立能同时检测中国红豆杉中微量紫杉醇、10-去乙酰巴卡亭Ⅲ(10-DAB)、巴卡亭Ⅲ(B-Ⅲ)、巴卡亭Ⅵ(B-Ⅵ)和1-乙酰-5,7,10-去乙酰巴卡亭Ⅰ(DAB-Ⅰ)等多种紫杉烷的方法,了解该植物中重要紫杉烷的分布和代谢特征。方法:采用电喷雾质谱(ESI-MS)和多级离子阱技术摸索紫杉烷的加合离子峰和碎裂离子出现规律,利用反相高效液相色谱法同时测定植物样品中5种紫杉烷的含量。植物样品用液氮快速研磨,甲醇浸提,固相萃取方法制样。色谱柱为 HypersilODS C_(18)(250mm×4.6mm,5μm),流动相为乙腈-甲醇-水(32:20:48),等度洗脱,流速为1mL·min^(-1),检测波长为227nm。结果:具有多个乙酰取代基的紫杉烷在 ESI-MS 正离子扫描时,产生强的铵加合离子峰,含羟基的紫杉烷易产生质子加合峰。最低检测限为0.5～1.5mg·L^(-1),紫杉醇在2.0～180mg·L^(-1)(r=0.9993),10-DAB 在2.0～166.0mg·L^(-1)(r=0.9975),B-Ⅲ在6～170mg·L^(-1)(r=0.9937),B-Ⅵ在7.0～200.0mg·L^(-1)(r=0.9921),DAB-Ⅰ在1.0～130mg·L^(-1)(r=0.9945)范围内具有良好的线性关系。紫杉醇回收率为98%±1.5%,日内 RSD 为1.8%,日间 RSD 为2.5%。结论:应用该方法测定了中国红豆杉不同组织中相应紫杉烷的含量,得到了良好的结果。

云南红豆杉中紫杉烷类化合物的分离与鉴定

目的 为了进一步研究红豆杉中的紫杉烷二萜类化合物 ,对生长在我国的云南红豆杉 Taxus yunnanensis进行深入的化学研究。方法 云南红豆杉枝叶的乙醇提取物 ,经萃取、硅胶柱层析、PTLC、制备 HPLC等方法分离 ,从乙醇提取物的二氯甲烷萃取部分分离得到 5个化合物 ,采用波谱解析 (U V,IR,ESI-MS,1 HNMR,1 3 CNMR)等方法确定了它们的结构。结果 分别为 1-acetoxy-baccatin ( ) ,7-epi-taxol( ) ,taxchinin A( ) ,cephalemannine( )和 taxol( )。结论 化合物 为新化合物 ,化合物 、

东北红豆杉茎皮化学成分研究

将东北红豆杉茎皮粉碎后用95％EtOH提取,再用CH_2Cl_2萃取,经柱层析分离,鉴定了3个化合物,分别为1-羟基巴卡亭I(baccatin I I-hydroxy)、2-去乙酰氧基红豆杉J(taxinine J 2-deacetoxy)和β-谷甾醇(β-sitosterol)。其中1-羟基巴卡亭I为首次从该植物中分得。

Natural Gas and Indoor Air Pollution: A Comparison With Coal Gas and Liquefied Petroleum Gas

Objective The study was designed to compare the combustion products of coal gas, liquefied petroleum gas and natural gas in relation to indoor air pollution. Methods Regular pollutants including B(a)P were monitored and 1-hydroxy pyrene were tested in urine of the enrolled subjects. Radon concentrations and their changes in four seasons were also monitored in the city natural gas from its source plant and transfer stations to final users. To analyze organic components of coal gas, liquefied petroleum gas and natural gas, a high-flow sampling device specially designed was used to collect their combustion products, and semi-volatile organic compounds contained in the particles were detected by gas chromatograph-mass spectrograph (GC/MS). Results Findings in the study showed that the regular indoor air pollutants particles and CO were all above the standard in winter when heating facilities were operated in the city, but they were lowest in kitchens using natural gas; furthermore, although NO2 and CO2 were slightly higher in natural gas, B(a)P concentration was lower in this group and 1-hydroxy pyrene was lowest in urine of the subjects exposed to natural gas. Organic compounds were more complicated in coal gas and liquefied petroleum gas than in natural gas. The concentration of radon in natural gas accounted for less than 1‰ of its effective dose contributing to indoor air pollution in Beijing households. Conclusion Compared to traditional fuels, gases are deemed as clean ones, and natural gas is shown to be cleaner than the other two gases.

Identification of missing CYP450 enzymes involved in paclitaxel biosynthesis and heterologous reconstitution of baccatin III

Paclitaxel,a tetracyclic diterpenoid,has garnered attention for its potent anti-cancer properties and intricate molecular structure,making it a significant target for chemical synthesis and biosynthesis[1].However,its natural sources are extremely limited,as it is derived exclusively from the bark of endangered genus Taxus plants,which contain paclitaxel in very low concentrations(0.01%−0.05%)[2-3].Recent advances in synthetic biology present promising opportunities to enhance paclitaxel levels in Taxus cell cultures or to enable the reconstitution of its production in heterologous hosts,such as yeast or tobacco(Nicotiana benthamiana).

披针叶茴香果实的化学成分研究

目的研究八角科（Illiciaceae）植物披针叶茴香（Illicium lanceolatum）果实的化学成分。方法应用硅胶、Sephadex LH-20、MCI等各种色谱技术进行分离纯化，根据化合物的理化常数和波谱数据鉴定其结构。结果从披针叶茴香果实的体积分数95％乙醇提取物中分离得到12个化合物，通过渡谱数据和理化常数分别鉴定为2，4-dihydroxy—allylbenzene-2-O-β-D—glucopyranoside（1），（＋）-儿茶素（2），槲皮素-3-O-β-L-鼠李糖苷（3），芦丁（4），异鼠李素-3-D-β-D-芸香糖苷（5），6-deoxy-1-hy—droxy neoanisatin（6），莽草毒素（7），icarisideE3（8），（75，8R）-urolignoside（9），对羟基苯甲酸（10），莽草酸（11），β-谷甾醇（12）。结论化合物1，4～6，8～10为首次从该植物中分离得到。

An Alternative Method for Anomeric Deacetylation of Per-acetylated Carbohydrates

An alternative method for anomeric deacetylation of fully acetylated carbohydrates has been developed using imidazole in methanol.

CuCl/Zn-promoted Mukaiyama Aldol Reaction of Phenyl a-fluoro silyl enol ether with Aldehydes

Fluoro-1-phenyl-1-trimethylsiloxyethene reacted efficiently with aldehydes to give a-fluoro -hydroxy ke-tones in HMPA in the presence of Zn powder and CuCl.