Three novel bicyclic 3,8-secotaxane diterpenoids from the needles of the chinese yew, taxus chinensis var. mairei

Taxanes and taxoids of the genus Taxus - A comprehensive inventory of chemical diversity

The pseudoalkaloid diterpene Taxol® (paclitaxel) emerged as a best-selling anti-cancer drug in the mid-1990s. The compound attracted considerable interest because of its unique mechanism to stabilize microtubules, thus reducing dynamicity and ultimately promoting mitotic arrest. Taxol was originally isolated from members of the genus Taxus. Over the last 50 years, close to 600 metabolites with taxane scaffolds were isolated from various Taxus species and their structures reported. The present review article provides an overview of the known chemical diversity of taxanes, with an emphasis on the functionalization of diterpene scaffolds. The implications of the occurrence of chemically diverse taxane metabolites for unraveling Taxol biosynthesis and enabling pathway engineering are discussed as well.

The verticillenes. Pivotal intermediates in the biosynthesis of the taxanes and the phomactins

Recent enzymatic studies, quantum chemical calculations and biomimetic conversions consolidate the role of verticillenes in the biosynthesis of taxanes and phomactins.

Oxygenated verticillene derivatives from Bursera suntui

Medium polarity fractions of the hexane extracts of the stems of Bursera suntui afforded six previously known (1-6) and four hitherto unknown verticillane derivatives: (1S,3Z,7S,8S,11S,12S)-(+)-7,8-epoxyverticill-3-en-12,20-diol (7), (1S,3Z,7S,8S,11S,12S)-(+)-7,8-epoxyverticill-3-en-12,20-diol 20-acetate (8), (1S,3Z,7S,11S,12S)-(+)-verticilla-3,8(19)-dien-7,12,20-triol (9), and (1S,3Z,7S,11S,12S)-(+)-verticilla-3,8(19)-dien-7,12,20-triol 20-acetate (10). Acetylation of 9 and 10 yielded (1S,3Z,7S,11S,12S)-(+)-verticilla-3,8(19)-dien-7,12,20-triol 7,20-diacetate (11), while hydrolysis of 8 gave 7. The structures and stereochemistry of 7-11 were established by spectroscopic analyses, particularly by 1D and 2D NMR spectra and HRESIMS. The conformational preferences of 7-11 were studied by molecular mechanics modelling employing the Monte Carlo protocol followed by B3LYP/DGDZVP DFT calculation, thus supporting the observed (1)H NMR NOESY cross peaks.

New Bicyclic Taxane Diterpenoids from Taxus sumatrana

Investigation of an acetone extract of the leaves and twigs of Taxus sumatrana has resulted in the isolation of two new bicyclic taxoids, tasumatrols M (1), and N (2) and a new baccatin III derivative, tasumatrol O (3) together with the previous known 7-deacetylcanadensene (4) and 2alpha,7beta,13alpha-triacetoxy-5alpha,9alpha-dihydroxy-2(3-->20) abeotaxa-4(20),11-dien-10-one. The structures of these taxanes were established on the basis of spectroscopic analyses, especially 1- and 2D NMR, and chemical derivatization.

Canadensenes: Natural and semi-synthetic analogues

The first bicyclic taxanes isolated in the needles of the Canadian yew were named canadensene 1 and 5-epi-canadensene 2. Four additional analogues (3–6), isolated previously in Taxus chinensis and Taxus mairei, and a new natural 5-epi-canadensene analog 7 with a C-20-cinnamoyl group, were characterized for the first time in the needles of Taxus canadensis. A bicyclic derivative 8 with a docetaxel side chain on C-20 was synthesized using 5-epi-canadensene 2 as starting material. The lack of bioactivities of these bicyclic analogues (tubulin polymerization and cytotoxicities against human cancer cell lines) is discussed.Key words: Taxus canadensis, Taxaceae, taxanes, natural products, semi-synthesis.

Three new taxane diterpenoids from the seeds of the Chinese yew, Taxus chinensis var mairei

Three new taxoids were isolated from the seeds of the Chinese yew, Taxus chinesis var mairei, their structures were established as 9alpha, 13alpha-diacetoxy-5alpha-cinnamoyloxy-11(15-->1)-abeo-taxa-4(20),11-diene-10beta, 15-diol, 2alpha,9alpha,10beta-triacetoxy-taxa-4(20),11-diene-5alpha,13alpha-diol and 2alpha,7beta,10beta-triacetoxy-5alpha-cinnamyloxy-9alpha-hydroxy-taxa-4(20),11-diene-13-one on the basis of 1D, 2D NMR, and MS spectral analyses.

Two new taxane diterpenoids from the seeds of the Chinese yew, Taxus yunnanensis

A new taxoid and a taxinine analogue were isolated from the seeds of the Chinese yew, Taxus yunnanensis. The structures were established as 13 alpha-acetoxy-5 alpha-(3'-dimethylamino-3'-phenyl)-propionyloxy-11(15-->1)-abeotaxa- 4(20),11-diene-9 alpha, 10 beta-diol and 2 alpha-acetoxy-5 alpha-cinnamoyloxy-9 alpha, 10 beta-dihydroxy-taxa- 4(20),11-diene-13-one on the basis of 1D, 2D NMR, and MS spectral analysis.

Three new bicyclic taxane diterpenoids from the needles of Japanese yew, Taxus cuspidata Sieb. et Zucc

Three new bicyclic taxane diterpenes were isolated from the needles of the Japanese yew, Taxus cuspidata Sieb. et Zucc. Their structures were established to be 7,9,10,13-tetraacetoxy-5-cinnamoyloxy-4-hydroxy-methyl-8,12,15,15- tetramethyl-bicyclo[9.3.1] pentadeca-3,8,11-trien-2-ol (2,20-dideacetyl taxuspine X), 7,9,10,13,20-pentaacetoxy-5-cinnamoyloxy-8,12,15,15-tetramethyl bicyclo[9.3.1] pentadeca-3,8,11-trien-2-ol (2-deacetyl taxuspine X), and 9,10,13,20-tetraacetoxy-5-cinnamoyloxy-8,12,15,15-tetramethyl-bicyclo[9.3.1] pentadeca-3,8,11-trien-2,7-diol (2,7-dideacetyl taxuspine X) with the aid of spectroscopic techniques and by comparing with taxuspine X.