Taxol® (Paclitaxel)

Taxol® (paclitaxel) has been hailed by many as the most promising new cancer treatment in two decades. The FDA requires that paclitaxel intended for human consumption be obtained only from the bark ofTaxus brevifolia, the Pacific yew. As this may become increasingly uneconomical, new strategies must be explored to ensure the continued availability of taxol and related molecules. This article examines the planning that must be engaged in and the contingencies that must be prepared for in this changing arena.     

Separation of 7-xylosyl-10-deacetyl paclitaxel and 10-deacetylbaccatin III from the remainder extracts free of paclitaxel using macroporous resins

The separation and enrichment of 10-deacetylbaccatin III (10-DAB III) and 7-xylosyl-10-deacetyl paclitaxel were studied on seven macroporous resins with special structures. The performance of 7-xylosyl-10-deacetyl paclitaxel and 10-DAB III on macroporous resins including AB-8, ADS-17, ADS-21, ADS-31, ADS-8, H1020 and NKA-II was compared according to their adsorption and desorption properties. AB-8 provided a much higher adsorption capacity for 7-xylosyl-10-deacetyl paclitaxel and 10-DAB III than other resins, and its adsorption data fitted well to the Langmuir and Freundlich isotherm. According to the adsorption and desorption capacities and the adsorption isotherms, AB-8 demonstrated a remarkable capability for the preparative separation of 7-xylosyl-10-deacetyl paclitaxel and 10-DAB III from the remainder extracts free of paclitaxel. In order to optimize parameters of separation, dynamic adsorption and desorption experiments were carried out on the columns packed with AB-8 resin. The optimal conditions were: the processing volume 15 BV; concentrations of 7-xylosyl-10-deacetyl paclitaxel and 10-DAB III in feed solution 0.0657 mg/mL and 0.1494 mg/mL; flow rate 1 mL/min; temperature 35 degrees C. The gradient elution program was as follows: 30% ethanol for 3 BV, then 80% of ethanol for 6 BV, flow rate 1 mL/min. After the AB-8 resin treatment, the contents of 7-xylosyl-10-deacetyl paclitaxel and 10-DAB III in the product had increased from 0.053% and 0.2% to 3.34% and 1.69%, which were 62.43-fold and 8.54-fold of those in the untreated extracts, respectively, and the recoveries of 7-xylosyl-10-deacetyl paclitaxel and 10-DAB III were 85.85% and 52.78%. The performance achieved good separation and higher recovery of 7-xylosyl-10-deacetyl paclitaxel and 10-DAB III from remainder extracts free of paclitaxel by using AB-8 resin. It is a fast and effective method for the separation and enrichment of 7-xylosyl-10-deacetyl paclitaxel and 10-DAB III.     

A Large Scale Separation of Taxanes from the Bark Extract of Taxus yunnanesis and 1H‐ and 13C‐NMR Assignments for 7‐epi‐10‐Deacetyltaxol

A large‐scale separation of paclitaxel from semi‐purified bark extract of Taxus yunnanesis was investigated. The chromatographic behavior of paclitaxel and two dose editing analogues, cephalomannine and 7‐epi‐10‐deacetyltaxol were systematically studied on a C₁₈ bonded phase column with different mobile phase in reverse phase mode. According to the notably different selectivity of the methanol and acetonitrile with water in the mobile phase and the most important requirement of capacity in preparative chromatography, the optimum suitably mobile phase used in a large‐scale isolation of paclitaxel and 7‐epi‐10‐deacetyltaxol on a preparative C₁₈ column was given. Cephalomannine was eliminated by ozonolysis and after then separated throughout a normal phase silica column. The whole large‐scale process for high purity paclitaxel from the bark extract of Taxus yunnanesis consisted of a preliminary purification with Biotage FLASH 150i system based on a prepacked normal phase silica cartridge followed by using a C₁₈ Nova‐pak? column in Waters PrepLC? 4000 preparative HPLC system. The structure of 7‐epi‐10‐deacetyltaxol was elucidated by 2D NMR technologies of TOCSY, DQF‐COSY, HMQC and HMBC, etc.     

Rewiring cellular metabolism for heterologous biosynthesis of Taxol

Abstract

Taxol is one of the anticancer drugs synthesized naturally in the evergreen Taxus brevifolia forest tree belonging to the yew family (Taxaceae) growing on the Pacific. There are reportedly evidence for treating ovarian, breast and lung cancers through this drug given its unique structural and functional features. Extraction of this drug from yew trees bark is one of the most common ways of producing this drug, but 3000 trees are needed to obtain a kilogram of Taxol. Hence, further attention has recently been attracted to the metabolic engineering strategies, including, engineering cellular metabolism of microorganisms and their optimization. Accordingly, the present paper article was aimed to review recent advances in elevating the production and commercialization of Taxol through metabolic engineering techniques.     

Determination of paclitaxel and its analogues in the needles of Taxus species by using negative pressure cavitation extraction followed by HPLC‐MS‐MS

A new separation method, negative pressure cavitation (NPC) extraction followed by HPLC‐MS‐MS for the determination of paclitaxel and its analogues in the needles of Taxus species is described in this study. Compared with three conventional extraction methods, NPC is a more effective, economical, and facile method for the separation of nature compounds from herbal plants. In contrast to high‐temperature extraction, NPC at low temperature can minimize undesirable reactions such as thermal decomposition or degradation. In addition, the extraction mechanism of NPC was also illuminated. The effects of vacuum degree, extraction solvent, ratio of solid to liquid, time, and times extraction were studied and optimized. The optimum extraction conditions were as follows: vacuum degree –0.03 MPa, solvent 80% v/v alcohol, ratio of material to liquid 1:15 (g/mL), extraction time 60 min, extraction (×3). Using these conditions, the recoveries of 10‐deacetyl‐7‐xylosylpaclitaxel, 10‐deacetylpaclitaxel, cephalomannine, and paclitaxel were higher than 95.88, 95.82, 94.85, and 96.18%, respectively. The contents of paclitaxel, 10‐deacetyl‐7‐xylosylpaclitaxel, 10‐deacetylpaclitaxel, and cephalomannine for Taxus chinensis were 0.0053, 0.0467, 0.0132, and 0.0076%, and 0.0067, 0.0153, 0.0047, and 0.0064% for Taxus cuspidata, respectively. Furthermore, a comparison of SEM images observed the morphological changes of microstructures and cellular damage in yew needles.     

Taxane Diterpenoids from the Root Bark of Taiwanese Yew Taxus Mairei

Nineteen compounds including taxumairol R (1) , taxinine M (2) , taxacin (3) , paclitaxel (4) , 10‐deacetyltaxol A (5) , 10‐deacetyl‐7‐epi‐taxol (6) , 7‐epi‐taxol (7) , taxol C, 10‐deacetyltaxol C, 7β‐xylosyl‐10‐deacetyltaxol (8) , taxamairin A (9) , taxinine A, 14β‐hydroxytaxusin (10) , 5α‐hydroxy‐7β,9α,10β, 13α‐tetraacetoxy‐4(20), 11‐taxadiene, 1‐dehydroxybaccatin‐VI, 1β‐dehydroxybaccatin‐IV, baccatin IV, baccatin VI and ponasterone A have been isolated and identified from the root bark of Taxus mairei. Among them, compound 1 was a new taxoid and compounds 11 and 7β‐xylosyl‐10‐deacetyltaxol pentaacetate were new derivatives prepared from 14β‐hydroxytaxusin (10) and 8 , respectively. Their structures and assignment were established on the basis of 2D‐NMR analysis and chemical methods.     

4-Deacetylbaccatin III: a proposed biosynthetic precursor of paclitaxel from the bark of Taxus wallichiana

4-Deacetylbaccatin III was isolated and characterized from the bark of Taxus wallichiana Zucc. It was previously identified as an intermediate during the synthesis of paclitaxel and was proposed as a precursor for the biosynthesis of paclitaxel. Existence of 4-deacetylbaccatin III in T. wallichiana is strong evidence for the previously proposed biosynthetic pathway of paclitaxel via 4-deacetylbaccatin III.     

Novel poly(aryl ether phthalazinium) ionomers and their properties

The synthesis of N-phenyl phthalazinium salts by condensation of a 1,2-diaroylbenzene with phenylhydrazine is described. This reaction was utilized to prepare novel poly(aryl ether phthalazinium) ionomers by the direct condensation of poly(aryl ether ketone)s with phenylhydrazine. The preparation of poly(aryl ether phthalazinium) ionomers by methylation of poly(aryl ether phthalazine)s is also described. Most of the ionomers are amorphous, thermally stable, and soluble in organic solvents. They can be cast into flexible and strong films. The glass transition temperature of the ionomers ranges from 297 to 363°C, an increase of 12 to 100°C over the corresponding neutral polymers. © 1996 John Wiley & Sons, Inc.     

高效液相色谱指纹图谱法分析南方红豆杉药材的氯仿提取物

建立了南方红豆杉药材氯仿提取物的高效液相色谱(HPLC)指纹图谱分析方法。采用Eurospher 100 C18色谱柱(250 mm×4 mm, 5 μm),以甲醇和水为流动相进行梯度洗脱,流速为1 mL/min,检测波长为232 nm,柱温为30 ℃。以10-脱乙酰巴卡亭III(10-DABIII)为参照物,在相同的色谱条件下测定了10批不同产地的南方红豆杉药材氯仿提取物的指纹图谱,获得了11个共有指纹峰,并利用主成分分析法(PCA)对指纹图谱进行统计分析。结果表明南方红豆杉药材的质量与种植区域有关。该方法稳定、可靠,可用于南方红豆杉药材的质量控制。     

Simultaneous determination of main taxoids in Taxus needles extracts by solid-phase extraction-high-performance liquid chromatography with pentafluorophenyl column

A simple and accurate RP-HPLC method with pentafluorophenyl (PFP) column was developed for the simultaneous determination of six taxoids, i.e. paclitaxel, 10-deacetylbaccatin III (10-DAB III), 7-xylosyl-10-deacetyltaxol (7-xyl-10-DAT), 10-deacetyltaxol (10-DAT), cephalomannine and 7-epi-10-deacetyltaxol (7-epi-10-DAT), in the extracts from the needles of three Taxus species. The mobile phase consisted of acetonitrile (A) and water (B), and the extracts were separated using gradient elution program: 30% A at the first 7 min, and then ramped to 42% A at 8 min, held until 38 min. The developed method was validated with satisfactory precision (RSD < 2.61%), repeatability (RSD < 2.92%) and recovery (95.19-104.47%). The above taxoids in the extracts of Taxus cuspidata, T. chinensis and T. media were analyzed with the developed RP-HPLC method, and the results showed that the contents of different taxoids in three mentioned species were distinct. Maximal amounts of 10-DAB III, 7-xyl-10-DAT and 7-epi-10-DAT appeared in T. chinensis, while T. media possessed the highest content of 10-DAT, cephalomannine and paclitaxel. The developed method is accurate and efficient. It can be reliably used in the improved determination of taxoids for the quality control of Taxus species.     

Preparative separation and enrichment of four taxoids from Taxus chinensis needles extracts by macroporous resin column chromatography

An environment‐friendly method was established for the preparative separation and enrichment of four taxoids, namely 10‐deacetylbaccatin III (10‐DAB III), 7‐xylosyl‐10‐deacetyltaxol (7‐xyl‐10‐DAT), cephalomannine and paclitaxel from Taxus chinensis needles extracts. Characteristics of seven widely used macroporous resins for four taxoids were compared, AB‐8 resin offered better adsorption and desorption capacities than others. AB‐8 resin column chromatography was used to study the desorption process for four taxoids. The optimum parameters for desorption were 30% ethanol 5 RV for removing impurities, following 15 RV for 10‐DAB III, after the desorption of impurities with 35% ethanol 10 RV, 45% ethanol 30 RV for 7‐xyl‐10‐DAT, then 65% ethanol 10 RV for cephalomannine and paclitaxel, the flow rate was 6 RV/h. After separation on AB‐8 resin column chromatography, the contents of 10‐DAB III, 7‐xyl‐10‐DAT, cephalomannine and paclitaxel in the product reached 4.58, 13.17, 1.36 and 3.08%, respectively, which were 7.63‐, 3.68‐, 6.18‐ and 6.55‐fold to those in T. chinensis needles extracts. The recovery yields were 94.96, 77.32, 88.09 and 95.25%. In general, the AB‐8 resin column chromatography has the advantages of lower cost, high efficiency and simple procedure. Therefore, it may provide scientific references for the preparative separation and enrichment of taxoids from other T. species.     

Screening for pharmaceutically important taxoids in Taxus baccata var. Aurea corr. with CC/SPE/HPLC-PDA procedure

Needles of 'the golden yew' Taxus baccata var. Aurea Corr. were extracted with methanol followed by pre-purification of the crude extract and column chromatographic (CC) separation on florisil in gradient mode (an increasing concentration of acetone in dichloromethane). The obtained fractions were concentrated and purified on silanized silica gel SPE cartridges and taxoids eluted with 75% methanol were analysed by HPLC-PDA procedure using Waters Symmetry C(18) column with gradient elution. The applied method enabled not only determination of four taxoids commonly occurring in yew extracts (10-deacetylbaccatin III, baccatin III, paclitaxel and cephalomannine), but also, on the basis of chromatographic behaviour and UV spectrum, 10-deacetylated taxoids (10-deacetylpaclitaxel, 10-deacetylcephalomannine, 7-xyloside-10-deacetylpaclitaxel and 10-deacetyltaxol C) could be detected together with 7-epi-10-deacetylpaclitaxel. From the needles of Taxus baccata var. Aurea Corr. the largest amounts isolated were of 10-deacetylbaccatin III, then 10-deacetylpaclitaxel and 7-xyloside-10-deacetylpaclitaxel, all compounds considered to be paclitaxel precursors in semisynthesis. The efficient mechanism of the separation of 10-acetylated taxoids from their 10-deacetylated derivatives on florisil on the basis of electron acceptor-electron donor interactions is discussed.     

工业色谱法分离制备7-木糖基-10-去乙酰紫杉醇酶解产物10-去乙酰紫杉醇

基于工业色谱法分离制备抗癌药物紫杉醇的半合成前体10-去乙酰紫杉醇(10-DAP)。7-木糖基-10-去乙酰紫杉醇(10-DAXP)在我国特有红豆杉品系(中华红豆杉)枝叶中含量丰富,以其为原料可制备紫杉醇最理想的半合成前体——10-DAP。本研究以部分纯化后的7-木糖基-10-去乙酰紫杉烷为原料,通过β-木糖苷酶水解该粗提物中的主要成分10-DAXP及其两个微量类似物7-木糖基-10-去乙酰三尖杉宁碱(10-DAXC)和7-木糖基-10-去乙酰紫杉醇C(10-DAXP C),脱去其C-7位上的木糖基,水解产物采用大孔吸附树脂吸附,正相快速柱分离和反相制备色谱分离,可获得高纯度的目标物10-DAP,产物纯度为96%,整个工艺的收率大于75%。该方法适合以10-DAXP为原料大规模制备紫杉醇的半合成前体化合物10-DAP,为工业化生产紫杉醇开辟了一条新途径。     

新乡红豆杉中多种紫杉烷类化合物的反相高效液相色谱分析

采用反相高效液相色谱法(RP-HPLC)研究了新乡种植红豆杉树皮中的多种紫杉烷类化合物.结果表明,新乡种植红豆杉树皮中的10-去乙酰巴卡丁Ⅲ、巴卡丁Ⅲ、7-木糖-10-去乙酰基三尖杉宁碱、7-木糖-10-去乙酰基紫杉醇、7-木糖-10-去乙酰基紫杉醇C、10-去乙酰基紫杉醇、三尖杉宁碱和紫杉醇的平均含量(质量分数,n=...     

Monitoring of Paclitaxel, Taxine B and 10-Deacethylbaccatin III in Taxus baccata L. by Nano LC–FTMS and NMR Spectroscopy

In this work, an aqueous extraction method has been combined with a preparative LC for isolation of 10-deacetylbaccatin III (10-DAB) from leaves of Taxus baccata L. The extracted aqueous solution showed two major peaks in LC. Semi-preparative-LC was used for isolation of these peaks. Nano liquid chromatography-Fourier transform mass spectrometry and nuclear magnetic resonance showed that these peaks belong to taxine B and 10-DAB in the extracted aqueous solution. The residual sample of aqueous extraction solution was extracted again by MAE. The amount of paclitaxel in Taxus baccata L. was compared with and without aqueous extraction and results showed that paclitaxel was stable and had no significant difference in concentrations during this aqueous extraction process.     

Synthesis and characterization of bromo‐, arylazo‐, and heterocyclic‐fused troponoids containing a 1,3‐benzodioxole system

A facile synthesis of a series of novel bromo‐, arylazo‐, and heterocyclic fused troponoid compounds containing 1,3‐benzodioxole system is described. The 7‐bromo‐, 5,7‐dibromo‐, and 5‐arylazo‐substituted 3‐[(2E)‐3‐(1,3‐benzodioxol‐5‐yl)prop‐2‐enoyl]tropolones ( 2 , 3 , and 5 , 6 , 7 ) were obtained by direct bromination or azo‐coupling reactions of 3‐[(2E)‐3‐(1,3‐benzodioxol‐5‐yl)prop‐ 2‐enoyl]tropolone ( 1 ) with bromine, and diazonium salts of aniline derivatives, respectively. 3‐[(2E)‐3‐(1,3‐Benzodioxol‐5‐yl)prop‐2‐enoyl]‐5‐bromotropolone ( 4 ) was obtained from 3‐acetyl‐5‐bromotropolone via one‐pot aldol dehydration reaction with piperonal. Tropolones 2, 3 , and 4 were subjected to nucleophilic cyclization with bifunctional hydroxylamine hydrochloride and phenylhydrazine hydrochloride to give the corresponding isoxazolo‐ and pyrazolo‐fused tropones ( 8 , 9 , 10 , 11 , 12 , 13 ), respectively. J. Heterocyclic Chem., (2012).     

Synthesis of some substituted 3-alkenyl-1-phenylpyrazoles

The regioselective synthesis of new 3-alkenyl-1-phenylpyrazoles 4 from the reaction of phenylhydrazine with 2,3-dihydro-4H-pyran-4-ones 1 is described.     

Chemistry and Biology of Taxol

One can view plants as a reference library of compounds waiting to be searched by a chemist who is looking for a particular property. Taxol, a complex polyoxygenated diterpene isolated from the Pacific Yew, Taxus brevifolia, was discovered during extensive screening of plant materials for antineoplastic agents during the late 1960s. Over the last two decades, interest in and research related to taxol has slowly grown to the point that the popular press now seems poised to scoop each new development. What was once an obscure compound, of interest only to the most masochistic of synthetic chemists and an equally small number of cellular biologists, has become one of the few organic compounds, which, like benzene and aspirin, is recognizable by name to the average citizen. In parallel, the scientific study of taxol has blossomed. Physicians are currently studying its effects on nearly every known neoplasm. Biologists are using taxol to study the mechanisms of cell function by observing the effects of its interactions with the cellular skeletal systems. Synthetic chemists, absorbed by the molecule's unique and sensitive structure and functionality, are exploring seemingly every available pathway for its synthesis. Indeed, the demand for taxol has risen so in the last five years that alternative sources to the extraction of T. brevifolia are being vigorously pursued. Because of the rapidly expanding scope of research in the multifaceted study of taxol, those who are interested in the field may find acquisition of a reasonable base of knowledge an arduous task. For this reason, this account attempts to bring together, for the first time, in a cogent overview the chemistry and biology of this unique molecule.     

Determination of main taxoids in Taxus species by microwave‐assisted extraction combined with LC‐MS/MS analysis

A method based on microwave‐assisted extraction (MAE) has been developed for the determination of paclitaxel and five related taxoids, namely 10‐deacetylbaccatin III (10‐DAB III), cephalomannine, 10‐deacetylpaclitaxel (10‐DAT), 7‐xyl‐10‐ deacetylpaclitaxel (7‐xyl‐10‐DAT), and 7‐epi‐10‐deacetylpaclitaxel (7‐epi‐10‐DAT) in Taxus species in this study. The influential parameters of the MAE procedure were optimized, and the optimal conditions were as follows: extraction solvent 80% ethanol solution, solid/liquid ratio 1:10 (g/mL), temperature 50°C, and three extraction cycles, each cycle 10 min. The method validation for LC‐MS/MS analysis was performed. The LOD and LOQ were 3.16–9.20 and 12.20–30.45 ng/mL, respectively. Repeatability and reproducibility for the six taxiods with RSD ranged from 2.78 to 3.85% and from 5.26 to 6.60%. The recoveries of the method for the six taxoids were 92.6–105.6%. The developed MAE‐LC‐MS/MS method was also successfully applied to determine the contents of six taxoids in different Taxus species.     

Ring transformation of 5-acylpyrimidines into 4-acylpyrazoles with hydrazine and phenylhydrazine in acidic medium

5-Benzoyl-4-methylpyrimidines 4a,b and 5-acetyl-4-phenylpyrimidines 5a,b reacted with hydrazines in alcoholic acidic medium to give respectively 4-acetyl-3-phenylpyrazoles 7, 9 and 10 and 4-benzoyl-3-methylpyrazoles 6, 8 and 11 . In the reaction with phenylhydrazine, 5-benzoyl-4-methyl-2-methylthiopyrimidine ( 4a ) led exclusively to 4-acetyl-1,3-diphenylpyrazole ( 10 ) as 5-acetyl4-phenyl-2-methylthiopyrimidine ( 5a ) led to 4-benzoyl-3-methyl-1-phenylpyrazole ( 11 ) via the initial formation of phenylhydrazones of pyrimidines 4a and 5a . However, 5-benzoyl-4-methyl-2-phenylpyrimidine ( 4b ) and 5-acetyl-2,4-diphenylpyrimidine ( 5b ) reacted with phenylhydrazine to afford, each of them, a mixture of two isomeric pyrazoles. The mechanism of these ring contraction reactions is discussed.