Structural determination of a new 2(3 --> 20)abeotaxane with an unusual 13beta-substitution pattern and a new 6/8/6-ring taxane from Taxus cuspidata

A new 2(3 --> 20)abeotaxane with an unusual 13beta-substitution pattern and a new 6/8/6-ring taxane were isolated from the methanol extract of the needles of Taxus cuspidata. The structures were established as 2alpha,7beta-diacetoxy-5alpha,10beta,13beta-trihydroxy-2(3 --> 20)abeotaxa-4(20), 11-dien-9-one (1) and 2alpha,5alpha,7beta,9alpha,13alpha-pentahydroxy-10beta-acetoxytaxa-4(20),11-diene (2) on the basis of 1D and 2D NMR spectral data and high-resolution FAB-MS analyses.     

Four New Taxoids from the Barks of Taxus yunnanensis

The ongoing study of our previous work1-4 led to the isolation of four new taxoids from the barks of Taxus yunnanensis. One of them belonged to a paclitaxel analogue named 7-xylosyl-taxol D, the others were 11(15?1)-abeotaxoids with an opened D-ring system, named taxuyunnanines P-R respectively. Their structures were determined by means of spectral method s including 1D and 2D NMR spectroscopy.7-Xylosyl-taxol D (1), white powder, has a molecular formula, C49H61NO18, from its positive HR…     

Novel taxane diterpenes from Taxus sumatrana with the first C-21 taxane ester

Phytochemical investigation of the taxane diterpenes content of an acetone extract of the leaves and twigs of Taxus sumatrana (Taxaceae) has resulted in the isolation of five new taxane diterpenes esters, tasumatrols H-L (1-5) together with 13 known taxanes (11-23). Compound 5 is the first 21-carbon taxane ester to be isolated from a natural source. The structures of these taxanes as well as their derivatives were established on the basis of spectral analyses, especially MS as well as 1-and 2D NMR. Compounds 2 and 4 showed significant activity against human liver carcinoma (Hepa59T/VGH), human large cell carcinoma of the lungs (NCI), human cervical epitheloid carcinoma (Hela), human colon adenocarcinoma (DLD-1) and human medulloblastoma (Med) cell lines.     

Novel taxoids from the Chinese yew Taxus yunnanensis

Six new taxoids, taxuyunnanines W (1), X (2), Y (3), Z (5), 10-deacetyl-10-(β-glucopyranosyl)-yunnanxane (8), and 7-(β-xylosyl)-N-methyl-taxol C (10), as well as taxuchin B (4) and yunnanxane (7), have been isolated from the bark of Taxus yunnanensis. Compounds 1 and 2 were characterized as 11(15→1)-abeo taxoids containing an orthoester group, which have not been reported from any Taxus plants to date; isolates 3 and 5 are the examples of taxanes having a tetrahydronfuran ring, being reported only for the second time; and 8 is the first natural 6/8/6 skeletal type taxane glucosidic form. This is also the first report of a co-occurrence of xylosidation and N-methylation in a taxane (10). Compound 4 is the only known chlorine-containing taxane found in nature thus far, and is being reported from this plant for the first time. The structures were determined by spectroscopic and chemical means including 1D and 2D NMR spectra.     

X-ray crystal structure of cytochalasin D produced by Tubercularia sp., a novel endophytic fungus of Taxus mairei

The crystal structure of cytochalasin D, which was isolated from Tubercularia sp., a novel endophytic fungus of Taxus mairei, and cocrystallized with dimethyl sulfoxide, is reported. The title compound crystallizes in the monoclinic space group P2₁, with a = 7.583(6) Å, b = 11.053(10) Å, c = 18.632(10) Å, = 95.79(6)°, V = 1553.6(3) ų, Z = 2. The structure was solved by direct methods and refined by least-squares methods to a final R factor of 0.103 for 2937 independent reflections.     

A simple and efficient sample preparation for taxanes in Taxus chinensis needles with natural menthol‐based aqueous deep eutectic solvent

Taxanes are natural anticancer constituents, and the sample preparation from matrix normally depends on organochlorine solvents. In this study, green and natural menthol‐based aqueous deep eutectic solvent was synthesized and used for sample preparation for taxanes. Five key parameters were optimized and the optimal preparation conditions were as follows: menthol/1‐propanol ratio 1:1 (mol/mol), solid–liquid ratio 1:30 g/mL, extraction time 30 min, ultrasonic power 250 W, and water content 80%. Under the above conditions, the total extraction efficiency of seven main taxanes was 1.25‐ to 1.44‐fold to the conventional methods. In addition, a high‐performance liquid chromatography method with C₁₈ column was established for quantitation of seven main taxanes in <25 min, which had excellent linearity (R² > 0.9986), precision (relative standard deviation < 3.00%), repeatability (relative standard deviation < 3.69%), and recovery (90.26–109.00%). This method performed the extraction, and enrichment processes simultaneously, and it had advantages such as high extraction efficiency, simple operation, low cost, and eco‐friendliness. This work indicated that the natural menthol‐based deep eutectic solvent aqueous could be an excellent alternative to the sample preparation from Taxus or other plants.     

A New Taxane Diterpenoid from the Seeds of Taxus yunnanensis

Plant from the genus of Taxus are a rich source of biologically active diterpennodsbelonging to the unique structural family of taxoids'. Although more than 300 taxoidswere isolated from yew tree', new taxoids still were isolated. In our continuing studieson the yew tree, we have previously isolated several new taxoids from seeds of theChinese yew, Taxus chinensiS var mairei. T yunnanensiS, and Japanese yew, TCuspidata'-'. Further investigation on the extract of the seeds of T yunnanensis …     

Taxayuntin I from Taxus Yunnanensis

Taxayuntin I, a new 11 (15->l)abeotaxane, was isolated from the leaves and stems of Taxus yunnanensis. Its structure was elucidated on the basis of spectroscopic data.     

Purification and characterization of Taxol and 10-Deacetyl baccatin III from the bark,needles, and endophytes of Taxus baccata by preparative high-performance liquid chromatography,ultra-high-performance liquid chromatography-mass spectrometry,and nuclear magnetic resonance

Taxol and 10-Deacetyl baccatin III are major taxanes in the bark, needles, and endophytes of Taxus baccata. The current study aimed to develop a process for their separation from different matrices. Crude taxoid was prepared by extraction of samples with methanol, followed by partitioning with dichloromethane and precipitation with hexane. Analytical high-performance liquid chromatography involved isocratic elution on C18 column (4.6 × 250 mm, 5 μm) with methanol-water (70:30 v/v) at a flow rate of 1 ml/min. Injection volume was 20 μl and detection was carried out at 227 nm. The content of Taxol and 10-Deacetyl baccatin III in bark, needles and endophytic culture broth was 11.19 and 1.75 μg/mg; 11.19 and 1.75 μg/mg; and 2.80 and 0.22 μg/L, respectively. Preparative high-performance liquid chromatography was done on C18 column (10 × 250 mm, 5 μm) at a flow rate of 10 ml/min. About 20 g crude taxoid was processed in < 3 h with a recovery of about 90% for both the analytes. The purity of recovered Taxol and 10-Deacetyl baccatin III determined by ultra-high-performance liquid chromatography-mass spectrometry was found to be 95.78 ± 3.63% and 99.72 ± 0.18%, respectively. The structure of recovered Taxol was confirmed by nuclear magnetic resonance. The method can find use in biotransformation studies.     

Preparative isolation of paclitaxel and related taxanes from cell cultures of Taxus chinensis using reversed-phase flash chromatography

In this study, paclitaxel, baccatin III, taxuyunnanine C and sinenxane C were successfully separated by reversed-phase flash chromatography on a manually packed C₁₈ column from Taxus chinensis cell culture extract. The crude cell culture extract was first treated with Al₂O₃ column chromatography and then divided into two parts: fraction 1 and fraction 2. Ten milligrams of baccatin III and 19 mg of paclitaxel were obtained from 100 mg dried fraction 1. Fifty-two milligrams of taxuyunnanine C and 11 mg sinenxane C were obtained from 100 mg dried fraction 2. The purities of the four compounds were 98.02%, 98.53%, 98.93% and 98.76%, respectively. Their structures were characterised by using UV, MS and NMR. These results indicate that paclitaxel and related taxanes including baccatin III can be obtained from cell culture in a highly pure state using reversed-phase flash chromatography.