Taxanes from Taxus x media* 1 (original) (raw)

Taxoids from the Roots of Taxus × media cv. Hicksii

Journal of Natural Products, 1994

A%mm.-The roots of TaxusXmpdia cy. Hicksii gave two new pseudoalkaloidal taxoids, identified as N-debenzoyl-N-butanoyl taxol [l] and 7/3-acetoxy-9-acetylspicataxine [2a]. A new baccatin IV derivative Val and the lignans hydroxymatairesinol [SI and (-)-epinomachelogenin E91 were also isolated. The epoxidation of Aqz0)''' taxadienes was investigated, disclosing an unusual reactivity of the bridgehead double-bond towards peracids. Regiochemically and stereochemically unnatural epoxides of taxoids were obtained. Nmr data for these compounds were compared with literature values on the natural epoxides. No significant correlation between the configuration of the 4(20)-oxirane ring and the chemical shift of H-5 was found. The stem bark and the needles of several species of yew have been thoroughly investigated (2), but very few studies have been done on the constituents of the roots (3,4). As part of a study aimed at assessing the availability of taxol and taxol-equivalent diterpenoids from cultivated yew species, we investigated the constituents of the roots of T. Xmediu Rehd. cv. Hicksii (5). This yew was developed for ornamental purposes and is popular as landscape material. Extensive cultivations exist in nurseries, and the needles have been studied as a potential source of taxol(6). A previous study has shown the presence of taxol and two novel analogs in the roots (7). We report here the isolation of three new taxoids El, 2a, 7a7 and of a lignan not previously described as a natural product E97. RESULTS AND DISCUSSION ' Compound 1 has the molecular formula C44H53N0,4 (cims). Its 'H-nmr spectrum was similar to that of taxol C (N-debenzoyl-N-hexanoyl taxol) (7). The only significant difference was the absence of the w-2 and w-3 methylene protons of the N-acyl residue. The 13C-nmr spectrum was almost superimposable on that of taxol C (7) except for the absence of the 0-2 and 0-3 carbons. These data suggested that 1 differs from taxol C by 'Part 14 in the series "The Chemistry and Occurrence of Taxane Derivatives." For part 13, see Appendino et al. (1).

A new taxane from Taxus canadensis needles

Chemistry of Natural Compounds, 2012

Paclitaxel (Taxol ® ) [1] by virtue of its complex and densely functionalized, challenging and seductive structure, coupled with its novel mechanism of action, potent antitumor activity, and its clinical use as a powerful anticancer drug used for the treatment of ovarian and breast cancers as well as Kaposics sarcoma and non-small-cell lung cancers, has attracted the attention of many chemists and biological scientists. Indeed, taxol and its analogues continue to stimulate a great deal of interest in the isolation of further taxoids from plants in the genus Taxus. As a result, more than 550 taxane diterpenoids have been isolated and identified . The isolation of new and minor taxanes is important in the context of the plant biosynthesis and metabolism of these compounds .

Minor Taxoids from Taxus wallichiana

Journal of Natural Products, 1995

ABSmm.-The needles of Taxus wallichiama afforded a new analogue of taxinine M [la] and two derivatives of brevifoliol [2a,3a]. The conformation of 3a was investigated by n m r spectroscopy with the aid of variable-temperature experiments and in situ reactions. The needles of the Himalayan yew (Taxus wallichiana Zucc., Taxaceae) are a valuable and renewable source ofpaclitaxel (=Taxol@) and paclitaxel analogues (2). Several other taxoids have been isolated, including one of a novel structural. type

New taxoids fromTaxus baccata L

Liebigs Annalen, 1995

A side-cut of the industrial purification of an extract of yew needles afforded eight new taxoids, including two derivatives of taxine A, the 7-0-acetyl-(2) and the 2-deacetyl-(3) derivatives. The new structures were established by spectroscopic methods, and some unusual features of the 'H-NMR spectra of taxine A and its derivatives are discussed.

Isolation of a new taxane fromthe needles of Taxus baccata L

A phytochemical investigation of the MeOH extract of the needles of Taxus baccata afforded new taxane: 7, 10-diacetyl-2,9-dihydroxy-5-cinnamatetaxa-4(20),11-diene-13-one. The structure of this compound was characterized by spectroscopic methods, including 1D-NMR, 2D-NMR, MS and IR.

New 6/8/6-Taxanes Isolated from the Heartwood of Taxus cuspidata

Helvetica Chimica Acta, 2012

Two new natural taxanes were isolated from the heartwood of Taxus cuspidata. The structures were established as rel-(2a,5a,7b,9a,10b,12a)-7,9-bis(acetyloxy)-2-(benzoyloxy)-11,12-epoxy-1,5-dihydroxy-10-[(hydroxyacetyl)oxy]tax-4(20)-en-13-one (1), and (2a,5a,10b,14b)-taxa-4(20),11-diene-2,5,10,14-tetrol 2-acetate (2) on the basis of spectroscopic analysis.

Tri- and Bicyclic Taxoids from the Taiwanese Yew Taxus sumatrana

Helvetica Chimica Acta, 2009

Five new taxoids, including a new 2(3 ! 20)-abeo-taxane with a 6/10/6-membered ring system and four 3,8-seco-taxanes having a 6/12-membered ring system, were isolated from an acetone extract of the leaves and twigs of the Taiwanese yew (Taxus sumatrana, Taxaceae). The structures were established as 2a,7b,10a-triacetoxy-5a-hydroxy-2(3 ! 20)-abeo-taxa-4(20),11-dien-9,13-dione (1), (3E,8E)-2a,9,10b, 13a,20-pentaacetoxy-7b-hydroxy-3,8-secotaxa-3,8,11-trien-5-one (2), (3E,8E)-2a,9,10b,13a,20-pentaacetoxy-5a,7b-dihydroxy-3,8-secotaxa-3,8,11-triene (3), (3E,8E)-9,10b,13a-triacetoxy-2a,7b,20-trihydroxy-5a-[(2E)-cinnamoyloxy]-3,8-secotaxa-3,8,11-triene (4), and (3E,8E)-2a, 5a,7b,9,10b,13a-hexaacetoxy-20-hydroxy-3,8-secotaxa-3,8,11-triene (5), respectively, on the basis 1D-and 2D-NMR spectral analyses. The in vitro cytotoxic activity of compounds 1 -5 against four human tumor cell lines, including HeLa (cervical epitheloid), WiDr (colon), Daoy (medulloblastoma), and Hep2 (liver carcinoma) tumor cells was evaluated. Whereas compounds 1 -3 were inactive, the novel taxanes 4 and 5 showed significant cytotoxicity.