Taxus Canadensis Research Articles

First example of conformational exchange in a natural taxane enolate

A detailed NMR study and full assignments of the (1)H- and (13)C-NMR spectral data for a novel enolate taxane isolated from Taxus canadensis needles is described. The structures of two stable conformers were established using a combination of 1D and 2D NMR techniques including (1)H, (1)H-COSY, gs-HMQC, gs-HMBC, NOESY and T-ROESY. Ab initio quantum mechanical calculations were performed on the B3LYP/6-31G* level of basis set to assist the NMR findings.

Taxanes from Rooted Cuttings of Taxus canadensis

A 3,11-cyclotaxane (1), a new epoxytaxane (2), an abeo-taxane (3), and 26 known taxanes were isolated in rooted cuttings of the Canadian yew (Taxus canadensis) for the first time. Their chemical structures were characterized as 1 beta,2 alpha,9 alpha-trihydroxy-10 beta-acetoxy-5 alpha-cinnamoyloxy-3,11-cyclotaxa-4(20)-en-13-one (1), 2 alpha,9 alpha,10 beta-triacetoxy-11,12-epoxy-20-hydroxytaxa-4-en-13-one (2), and 7 beta,9 alpha,10 beta,13 alpha-tetraacetoxy-11(15-->1)abeo-taxa-4(20),11-diene-5 alpha,15-diol (3). Metabolite 2 is a new taxane, metabolite 1 has been reported previously in the needles of Taxus baccata, and metabolite 3 was previously discovered as a biotransformation product but is now reported as a natural product for the first time.

Taxanes with C-5-amino-side chains from the needles of Taxus canadensis

Five taxanes with an amino-side chain on C-5 were identified for the first time in the needles of the Canadian yew, Taxus canadensis. Their structures were characterized as 2α,7β,9α,10β,13-pentaacetoxy-11β-hydroxy-5α-(3′- N,N-dimethylamino-3′-phenyl)-propionyloxytaxa-4(20),12-diene ( 1), 2α,9α-dihydroxy-10β,13α-diacetoxy-5α-(3′-methylamino-3′-phenyl)-propionyloxytaxa-4(20),11-diene ( 2), 2α17-dihydroxy-9α,10β,13α-triacetoxy-5α-(3′- N,N-dimethylamino-3′-phenyl)-propionyloxytaxa-4(20),11-diene ( 3), 2α-hydroxy-7β,9α,10β,13α-tetraacetoxy-5α-(2′-hydroxy-3′- N,N-dimethylamino-3′-phenyl)-propionyloxytaxa-4(20),11-diene ( 4), and 9α-hydroxy-2α,10β,13α-triacetoxy-5α-(3′- N,N-dimethylamino-3′-phenyl)-propionyloxytaxa-4(20),11-diene ( 5) on the basis of 1D-, 2D-NMR spectroscopic data and high-resolution fast atom bombardment MS analyses. Metabolite ( 1) was isolated from the needles of the Canadian yew for the first time but had previously been detected in the stems of the Japanese yew, whereas taxanes ( 2– 5) are only now reported. Metabolite ( 3) is the first reported nitrogen-containing taxane with a 17-hydroxyl substitution.

First Three Examples of Taxane‐Derived Di‐propellanes in Taxus canadensis Needles.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Continuing Environmental Change - An Example from Nova Scotia

Information from personal experience, from community elders and published literature served as a basis for evaluating environmental changes in the District of North Queens and adjacent areas of Southwestern Nova Scotia over the past century. Major events included disappearance of the Caribou (Rangifer tarandus), the arrival of White-tailed Deer (Odocoileus virginianus), the severe reduction of Canada Yew (Taxus canadensis), disappearance of Lynx (Lynx canadensis), a major dieoff of Striped Skunks (Mephitis mephitis), decline of American Beech (Fagus grandifolia), the loss of mature birch (Betula spp.), the severe reduction of Moose (Alces alces), the arrival of the American Dog Tick (Dermacentor variabilis) and Coyotes (Canis latrans), and the restoration of Beaver (Castor canadensis). The proximate cause of many of those changes were plant and animal disease, while the ultimate causes were naturally occurring animal range expansion and human impacts. The warming of the climate over the past 150 years probably played a role. The nature and timing of the events could not have been predicted.

New Minor Taxane Derivatives from the Needles of Taxus canadensis

Seven minor taxane derivatives were isolated for the first time from the needles of Taxus canadensis. Four of these natural taxanes are O-glycosylated (1-4), with 4 being the only reported taxane with a glucose on ring C, and two have a dimethylamino-C-5 side chain (5 and 6). An unusual double bond at C-5(6) has been identified in taxane 7.

Small Mammal Abundance and Diversity in Forests With and Without Canada Yew, <em>Taxus canadensis</em>

Canada Yew (Taxus canadensis) has been extirpated from much of its former range in northeastern North America possibly due to logging, fire, agriculture, and browsing by White-tailed Deer (Odocoileus virginianus). We compared the relative abundance and species diversity of small mammals in five northern hardwood stands containing Canada Yew to five adjacent stands without Canada Yew in the Upper Peninsula of Michigan, during October-November 2000. Overall, 72 individuals were captured (53 in yew, 19 in non-yew); dominant species were Short-tailed Shrew (Blarina brevicauda), Deer Mouse (Peromyscus maniculatus), and Red-backed Vole (Clethrionomys gapperi). Overall mean (+ sd) capture rate (individuals/100 adjusted trap nights) in sites with yew (5.5 + 2.2) was greater (P = 0.04) than mean capture rate in sites without yew (1.9 + 1.0). Three indices of species diversity suggested greater small mammal diversity in stands with Canada Yew understories in northern hardwood forests.

First Example of a Taxane‐Derived Propellane in Taxus canadensis Needles.

AbstractFor Abstract see ChemInform Abstract in Full Text.

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.

New taxanes from the needles of Taxus canadensis.

Ten new taxanes were isolated from the methanol extract of the needles of the Canadian yew, Taxus canadensis. On the basis of their spectral analysis, their structures were established as 9alpha-hydroxy-2alpha,7alpha,10beta-triacetoxy-5alpha-cinnamoyloxy-3,11-cyclotaxa-4(20)-en-13-one (1), 9alpha,10beta-diacetoxy-5alpha-cinnamoyloxy-3,11-cyclotaxa-4(20)-en-13-one (2), 9alpha,20-dihydroxy-2alpha,10beta,13alpha-triacetoxytaxa-4(5),11(12)-diene (3), 2alpha,9alpha,10beta-triacetoxy-20-cinnamoyloxy-11,12-epoxytaxa-4-en-13-one (4), 9alpha-hydroxy-2alpha,10beta,13alpha-triacetoxy-5alpha-(3'-methylamino-3'-phenyl)-propionyloxytaxa-4(20),11-diene (5), 2alpha,10beta-diacetoxy-5alpha,9alpha-dihydroxytaxa-4(20),11-dien-13-one (6), 2alpha,9alpha-diacetoxy-5alpha,10beta-dihydroxytaxa-4(20),11-dien-13-one (7), 5alpha,9alpha-dihydroxy-2alpha,10beta,13alpha-triacetoxytaxa-4(20),11-diene (8), 5alpha,10beta-dihydroxy-2alpha,9alpha,13alpha-triacetoxytaxa-4(20),11-diene (9), and 7beta,11beta-dihydroxy-2alpha,9alpha,10beta,13-tetraacetoxy-5alpha-cinnamoyloxytaxa-4(20),12-diene (10). Taxane 1 is the first example of a 3,11-cyclotaxane with a 7-epi-alpha-oxygenated group. Taxane 4 is the first taxane with a C-11,12-epoxide ring as well as a C-4(5)-endo-double bond. Taxanes with a 12(13) double bond as in 10 instead of the usual 11(12) double bond have been found so far only in the needles, stem, and seeds of the Japanese yew.

Semi-Synthesis of an O-Glycosylated docetaxel analogue

A 7β-O-glycosylated docetaxel analogue was semi-synthesized from 9-dihydro-13-acetylbaccatin III, the most abundant taxane isolated from the needles of Taxus canadensis. It was shown to be more bioactive than paclitaxel according to the tubulin assay. It had a reduced potency in the MCF7 cell line cytotoxicity assay compared to paclitaxel, but it demonstrated better activity against the drug resistant cell line MCF7-ADR. In addition, the presence of one sugar moiety on C-7 doubled the water solubility versus that of paclitaxel.

New minor taxanes analogues from the needles of Taxus canadensis

Seven new taxanes were isolated from the needles of the Canadian yew: unusual functional groups, positions and/or stereochemical features are described. Their chemical structures were rigorously characterized by detailed high resolution NMR analyses and confirmed by high resolution Fast Atom Bombardment Mass Spectrometry. Unlike paclitaxel and taxuspine D, these taxanes had no effect on tubulin assembly.

First example of a taxane-derived propellane in Taxus canadensis needles.

The first example of a propellane isolated from the needles of a yew is reported; the biogenesis from a putative taxane precursor is proposed.

A novel minor metabolite (taxane?) from Taxus canadensis needles

A novel minor metabolite 1 with an unprecedented skeleton was isolated from the needles of Taxus canadensis. A biogenesis from taxinine an abundant taxane is proposed. This is the first example of a taxane with a 6/6/8/6-membered ring skeleton.

Architectural and genotypic variation in the clonal shrub Taxus canadensis as determined from random amplified polymorphic DNA and amplified fragment length polymorphism

Canada yew (Taxus canadensis Marsh.) is a clonal species with two types of ramets. The most common type has bilateral symmetry and alternate branching. The radial symmetry and opposite branching of the rarer type are similar to the architecture expressed in a young plant grown from seed. Architectural analysis was conducted on four colonies of increasing age and size. A genetic analysis using random amplified polymorphic DNA (RAPD) and amplified fragment length polymorphism (AFLP) was conducted on 122 ramets, 93 sampled from nine colonies from a single population, 24 from eight other populations, and five from other Taxus species. Analysis of the architectural development sequence shows that yew follows the same architectural model as, for example, species of Abies or Picea. This model constitutes a level of organization intermediate between that of the ramet and of the genet. The molecular analyses confirm the greater variability of AFLPs over RAPDs and indicate that architecture is not directly related to genotypic variation. Ramets with radial symmetry have slightly higher genetic variation, on average, than ramets with bilateral symmetry with 95% degree of confidence. The molecular analyses show that the level of resolution of the AFLPs is adequate to characterize 98% of the ramets of a colony. Between pairs of physically connected ramets, some random genotypic differences are observed, supporting the hypothesis of genetic mosaicism in plants, due to somaclonal variations.Key words: architecture, clonal plant, intraclonal variation, molecular markers, somaclonal mutations.

Upland Old-Field Succession in Southeastern New Hampshire

HOWARD, L.F AND T.D. LEE. (Department of Plant Biology, University of New Hampshire, Durham, NH, 03824). Upland old-field succession in southeastern New Hampshire. J. Torrey Bot. Soc. 129: 60-76. 2002.A 22-site chronosequence was used to study old-field successional communities in Transition Hardwood forests of Durham, NH. Sites ranged from recently abandoned fields to hemlock forests greater than 200 years old. Trees, shrubs, and herbs were sampled in nested quadrats, and importance values were calculated. Increment borings were used to determine site ages. Five woody community types were identified using cluster analysis and ordination: 1) Gray Dogwood and 2) Juniper-Blackberry-Sweetfern (both early-successional, 14-23 years since abandonment), 3) White Pine and 4) Oak-Viburnum (both mid-successional, 50-150 years since abandonment), and 5) Hemlock (late-successional, 100-200+years since abandonment). Six herb stratum associations were found: 1) Kentucky Bluegrass and 2) Goldenrod-Dewberry-Buckthorn (both early-successional), and 3) Pennsylvania Sedge, 4) Wild Sarsaparilla, 5) Canada Mayflower, and 6) Canada Yew (all mid-late successional). Photosynthetically active radiation (PAR) declined exponentially over the 200-year chronosequence, and the temporal importance of woody species in the understory was associated with particular forest floor light levels. Actual succession at individual sites with similar soils may also be modified by previous land-use history, differential seed availability, and post-agricultural disturbance.

New taxane analogues from the needles of Taxus canadensis.

Eight minor taxanes have been identified for the first time in Taxus canadensis needles. Four of these metabolites are new taxane analogues: 7-acetyl-10-deacetyltaxol (1), 2'-acetyl-7-epi-cephalomannine (2), 10-deacetyl-10-oxo-7-epi-cephalomannine (3), and 10-acetylglycollylbaccatin VI (4).

Challenges in the isolation of taxanes from Taxus canadensis by fast pyrolysis

The Waterloo Fast Pyrolysis Process (WFPP) was used to determine the feasibility of extracting taxanes from needles, twigs and whole clippings of Taxus canadensis. Purification techniques developed for solvent extracts were not suitable for achieving analytic chromatographic separation of taxanes from pyrolytic lignins and other pyrolysis products as these materials are in much higher quantities in pyrolysis oil than in solvent extracts. A number of separation techniques were attempted including liquid–liquid partitioning, silica gel chromatography, adsorption and sodium phenoxide formation. Pretreatment of the feedstock by deionization was also attempted. Taxol® was identified in pyrolysis oils of needles and whole clippings with 20% recovery compared to solvent extraction. Other taxanes were most likely present in higher concentrations but could not be analyzed because of interference by phenolic substances.

Evidence for low genetic diversity and metapopulation structure in Canada yew (Taxus canadensis): considerations for conservation

Canada yew (Taxus canadensis Marsh.) is a gymnosperm that grows in the understory of mixed and deciduous forests of northeastern North America. This shrub had no economic importance until the discovery of paclitaxel, or TAXOL®, which is a compound found in plant tissue and used in cancer treatment. With the intensifying harvesting pressure on natural populations of this species, the natural gene pool might be affected. The objective of this study was to estimate the levels of genetic diversity and population structure in Canada yew, before any sizeable effects resulting from harvesting appear. Six natural populations of Canada yew were sampled in Quebec. Genetic diversity was estimated at 22 loci coding for 12 enzyme systems. At the population level, the number of alleles per locus was 1.32, the percentage of polymorphic loci was 26.5%, and the observed heterozygosity was 0.102. These results show that Canada yew is genetically less diverse than other yew species and the great majority of gymnosperms. However, the amount of population differentiation was substantially higher (FST= 10.2%) than that for other conifer and tree species growing in the boreal-temperate zone. Hypotheses related to the biogeography of the species and a likely metapopulation structure are proposed to explain the observed trends.

Oligosaccharides potentiate methyl jasmonate-induced production of paclitaxel in Taxus canadensis

The interdependence of methyl jasmonate (MJ) with chitin and chitosan derived elicitors in formation of paclitaxel was studied using plant cell suspension cultures of Taxus canadensis. Induction of paclitaxel biosynthesis was enhanced when MJ and elicitors were added 8 days after culture transfer compared to treatments in which only MJ or only elicitors were added. The enhancement of the paclitaxel biosynthesis response to MJ concentration was roughly linear between 0 and 200 μM using colloidal chitin or oligosaccharides of chitin and chitosan as elicitors. MJ concentrations greater than 200 μM were inhibitory. In kinetic studies, culture growth and substrate utilization were inhibited when the cultures were elicited with 100 μM MJ and with 0.63 mg l −1 N-acetylchitohexaose and with 100 μM MJ alone; paclitaxel yields were 10-fold greater under the latter condition than the former. Ethylene biosynthesis by the cell cultures in response to elicitation is implicated in regulation of the response.