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From an EtOAc-soluble extract of the roots of Taxus wallichiana, six new (1–6) and 11 known lignans were isolated. The structures of the new compounds were elucidated based on interpretation of spectroscopic data. (+)-7′-epi-Tsugacetal (1) is a rare aryltetralin-type lignan having a cis-orientation of H-7′ and H-8′. Compounds 3–6 were identified as the first naturally occurring tetrahydrofuranoid lignans having a cis-orientation of H-7 and H-8. All tested compounds were found to possess α-glucosidase inhibitory activity, with formosanol (9) showing the most potent effect with an IC50 value of 35.3 μM.

From a CH2Cl2 extract of the bark of Taxus wallichiana, six new taxoids, wallitaxanes A–F (1–6), were isolated, together with 29 known compounds. The structures of the new compounds were elucidated on the basis of spectroscopic data interpretation. Wallitaxane D (4) was identified as an opened oxetane-type taxoid having the first naturally occurring C(H)-20 acetal group, while wallitaxanes E (5) and F (6) are representative of the rare abeo-taxoid class. The isolated compounds were evaluated for their α-glucosidase inhibitory activity and for cytotoxicity against the HeLa human cervical cancer cell line. In the present work, taxanes were found to exhibit α-glucosidase inhibitory activity for the first time, and wallitaxane A (1) showed the most potent effect, with an IC50 value of 3.6 μM. In turn, 7-epi-taxol (16) and 7-epi-10-deacetyltaxol (17) showed IC50 values of 0.05 and 0.085 nM, respectively, against HeLa cells.

Taxus trees possess fungal endophytes reported to produce paclitaxel. Inhibitors that block early steps in plant paclitaxel biosynthesis were applied to a paclitaxel-producing fungus to determine whether these steps are shared. The plant paclitaxel backbone is reportedly derived from the non-mevalonate terpenoid pathway, while the side chain is phenylalanine-derived. Evidence that the shikimate pathway contributes to fungal paclitaxel was shown by decreased paclitaxel accumulation following inhibition of phenylalanine ammonia lyase. Expression of another shikimate pathway enzyme, 3-dehydroquinate synthase, coincided with paclitaxel production. The importance of the mevalonate pathway in fungal paclitaxel biosynthesis was shown by inhibition of fungal paclitaxel accumulation using compactin, a specific inhibitor of 3-hydroxy-3-methyl-glutaryl-CoA reductase. Expression of another mevalonate pathway enzyme, 3-hydroxy-3-methyl-glutaryl-CoA synthase, coincided with fungal paclitaxel accumulation. Unexpectedly, results from using fosmidomycin suggested that fungal paclitaxel requires 1-deoxy-D-xylulose-5-phosphate reductoisomerase (DXR), an enzyme in the 2-C-methyl-D-erythritol-4-phosphate (MEP) pathway normally found in bacteria/plants. Additional lines of evidence support this finding; first, a plant DXR antibody recognized a fungal peptide of the correct size; second, expression of an apparent fungal DXR ortholog correlated to changes in paclitaxel production; finally, BLAST searching identified a gene putatively encoding 1-deoxy-D-xylulose-5-phosphate synthase, the first enzyme in the MEP pathway in Aspergillus.

From the aqueous extract of the wood of Taxus yunnanensis, which showed cytochrome P450 3A4 (CYP3A4) inhibition, a new isoflavan [(3S,4R)-4'-hydroxy-6,3'-dimethoxyisoflavan-4-ol (1)], a new degraded lignan [2,3-bis(hydroxymethyl)-7-hydroxy-6-methoxy-1-tetralone (2)], and a new lignan [(7R)-7-hydroxytaxiresinol (3)] were isolated, together with nine known lignans. Among the isolates obtained, α-conidendrin (12) showed strong CYP3A4 inhibition with an IC(50) value of 0.2 μM.

Phytochemical investigation of the leaves and twigs of Taxus sumatrana afforded six new taxane diterpene esters, tasumatrols U-Z ( 1- 6). Compounds 2 and 5 contained a rare five-membered lactone ring at C-8, C-9, C-10, and C-19. The structures were established on the basis of detailed spectroscopic analyses, particularly HRESIMS and 2D NMR techniques. Compound 5 showed cytotoxicity against a human hepatoma (Hep2) cell line.

Luteibacter sp., a new bacterium isolated from the soil around a Taxus cuspidata Sieb. et Zucc plant, was studied for its capability to metabolize cephalomannine (1). After preparative fermentation, eight metabolites were obtained and characterized as baccatin III (2), baccatin V (3), 10-deacetylbaccatin III (4), 10-deacetyl-10-oxobaccatin V (5), 7-epicephalomannine (6), 10-deacetylcephalomannine (7), 10-deacetyl-7-epicephalomannine (8), and 3'-N-debenzoyl-3'-N-(2-methylbutyryl)-7-epitaxol (9). Among these metabolites, 9 is a new compound. Epimerization of the 7beta-OH group and hydrolysis of the C-13 side-chain were the two major reactions in this bioprocess. However, the biotransformation of 7beta-D-xylosyl-10-deacetyltaxol (10) with the same strain yielded a C-13 side-chain eliminated product without epimerization at C-7 (11). Metabolites 5-9 and 11, together with 1 and paclitaxel, were evaluated for their inhibitory activities against five human cancer cell lines (HCT-8, Bel-7402, BGC-823, A549, and A2780). All these compounds showed less potent activities than paclitaxel, which is currently used in clinical chemotherapy.

A new paclitaxel derivative and two new 2(3--20)-abeo-taxoids were isolated from a methanol extract of the seeds of Taxus mairei, and their structures were established as 1-deoxypaclitaxel (1), 7beta,10beta-diacetoxy-2alpha,5alpha,13alpha-trihydroxy-2(3--20)-abeo-taxa-4(20),11-dien-9-one (2), and 2alpha,13alpha-diacetoxy-10beta-hydroxy-2(3--20)-abeo-taxa-4(20),6,11-triene-5,9-dione (3) on the basis of spectroscopic data analysis. Taxane 1 is the first example of a paclitaxel analogue with a C-1beta hydrogen substituent. Taxane 3 is an 2(3--20)-abeo-taxane with a rare C-5 ketone and C-6 double bond.

Deacylation of a taxoid mixture isolated from the roots of Taxus mairei followed by chromatographic fractionation resulted in the isolation of three new taxoid derivatives, 2alpha,9alpha,10beta-triacetoxy-5alpha,14beta-dihydroxy-4(20),11(12)-taxadiene (1), 9alpha,10beta-diacetoxy-2alpha,5alpha,14beta-trihydroxy-4(20),11(12)-taxadiene (2), and 9alpha,10beta-diacetoxy-2alpha,5alpha,14beta-trihydroxy-4,20-epoxy,11(12)-taxene (3). Epoxidation of 2 afforded 9alpha,10beta-diacetoxy-2alpha,5alpha,14beta-trihydroxy-4,20:11,12-diepoxytaxane (6), while epoxidation of 4 yielded 9alpha,10beta-diacetoxy-5alpha,13alpha-dihydroxy-4,20-epoxy,11(12)-taxene (7) and 9alpha,10beta-diacetoxy-5alpha,13alpha-dihydroxy-4,20:11,12-diepoxytaxane (8). The structures were elucidated by detailed analysis of their NMR spectra. The structure and relative stereochemistry of 7 was confirmed by X-ray crystallography.

Approximately 120 taxoids have been isolated to date from the Japanese yew, Taxus cuspidata. These taxoids possess various skeletons containing 5/7/6-, 6/10/6-, 6/5/5/6-, 6/8/6-, or 6/12-membered ring systems. Among the taxoids, some non-paclitaxel-type compounds have been shown to reduce CaCl(2)-induced depolymerization of microtubules, increase cellular accumulation of vincristine in multidrug-resistant tumor cells, and exhibit potent cytotoxicity. Chemical derivatization of taxoids of T. cuspidata is also reviewed.

The research team of Dr. Monroe E. Wall and Dr. Mansukh C. Wani of Research Triangle Institute discovered two first-in-class life-saving chemotherapeutic agents. Camptothecin, first isolated and identified from Camptotheca acuminata, was found to kill cancer cells uniquely via topoisomerase I poisoning. Presently, two first-generation analogues of camptothecin are used to treat ovarian, colorectal, and small-cell lung cancers, and several second-generation analogues are in clinical trials. Taxol, first isolated and identified by Wall and Wani from Taxus brevifolia, was found to inhibit cancer cell growth via the stabilization of microtubules. In 1992, taxol was approved for refractory ovarian cancer and today is used against breast and non-small cell lung cancers and in Kaposi's sarcoma. While there have been numerous reviews of these molecules individually, this review offers an integrated account of the research team of "Wall and Wani" and the significance of their discoveries to chemistry, biology, and clinical medicine.

Two new taxoids, taxumairol Q (1) and 13-O-acetyl wallifoliol (2), have been isolated from the leaves and twigs of Taxus sumatrana. Taxuspine F and wallifoliol (10) have been isolated for the first time from the yew T. sumatrana. Seventeen known taxoid diterpenoids have also been isolated. The new derivatives, 9,13-diacetyltaxumairol W (3), 10,13-dibenzoyltaxacustin (4), 7,13-diacetylwallifoliol (5), 7,13-dibenzoylwallifoliol (6), and 7,9-dibenzoyltaxumairol P (7), have been prepared by acylation of a crude mixture of taxoids. All structures were established primarily on the basis of 1D and 2D NMR techniques, including DEPT, COSY, and HMBC experiments, as well as chemical correlation with known compounds. Wallifoliol (10) exhibited significant cytotoxicities against both Hepa 59 T/VGH (human liver carcinoma) and KB (human oral epidermoid carcinoma) tumor cells. Taxuspine F and compound 5 possessed moderate activity against Hepa cells only, while 3, 6, 7, and 10-deacetylbaccatin III showed only marginal activity against Hepa cells.

Two new taxane diterpenes, dantaxusin C (1) and dantaxusin D (2), were isolated from an ethanol extract of the aerial parts of Taxus yunnanensis along with 14 known taxoids. All structures were established on the basis of 1D and 2D NMR and HREIMS spectroscopic methods.

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).

Five new 11(15 -->1)-abeo-taxane diterpenoids, taxuyunnanines K-O (1-5), were isolated from an ethanol extract of the bark of Taxus yunnanensis, and their structures were determined using MS and NMR techniques. Compounds 1/2 and 4/5 are rearranged taxane diterpenoids possessing an opened oxetane ring moiety at C4(20). Compounds 4/5 are rearranged taxoids lacking an oxygenated functionality at C-4.

Cell suspension cultures of Taxus canadensis rapidly produced paclitaxel (1) and other taxoids in response to elicitation with methyl jasmonate. Three of these taxoids, of potential value in the synthesis of taxoid analogues, have been isolated from cell cultures of Taxus canadensis and identified as 13-acetyl-9-dihydrobaccatin III (2), baccatin VI (3), and 9-dihydrobaccatin III (4). Of these metabolites, 9-dihydrobaccatin III (4) has not been isolated from any Taxus species, whereas 13-acetyl-9-dihydrobaccatin III (2) and baccatin VI (3) have been isolated from a number of natural sources. 2D NMR techniques, mass spectrometry, and partial synthesis were used to rigorously elucidate the structure and stereochemistry of these natural products.

Five novel taxanes (1-5) have been isolated from the needles of Taxus canadensis, and their structures were elucidated on the basis of spectroscopic data. Two of these taxanes have structural features seldom found in yews, with a C-12, C-13 double bond and a hydroxymethylene at C-4. In addition, the 2D structures generated by molecular modeling of taxanes 1 and 2, differing mostly in the location of the double bond in ring A, were compared. The different conformation of ring A derived from the C-12, C-13 double bond is particularly interesting because it implies that if a Taxol (paclitaxel) side chain were attached to C-13 it would have a different orientation from that in paclitaxel.

Six new taxane diterpenoids and three known 2(3-->20)abeotaxoids were isolated from the seeds of Taxus chinensis var. mairei and of Taxus yunnanensis. Their structures were established as 2alpha, 20-dihydroxy-9alpha-acetoxytaxa-4(20),11-dien-13-one (1), 5alpha-cinnamoyloxy-7beta,10beta, 13alpha-triacetoxy-2(3-->20)abeotaxa-2alpha-ol-4(20),11-dien-9-one (2), 5alpha-cinnamoyloxy-10beta, 13alpha-diacetoxy-2(3-->20)abeotaxa-2alpha,7beta-diol-4(20), 11-dien-9-one (3), 5alpha-cinnamoyloxy-2alpha,7beta,10beta, 13alpha-tetraacetoxy-2(3-->20)abeotaxa-4(20),11-dien-9-one (4), 7-O-acetyltaxine A (5), 2alpha,7beta,10beta, 13alpha-tetraacetoxy-5alpha-phenylisoserinatoxy-2(3-->20)abeotaxa-4(2 0),11-dien-9-one (6), 5-O-acetyltaxinine M (7), 5alpha-hydroxy-2alpha,7beta,10beta, 13alpha-tetraacetoxy-2(3-->20)abeotaxa-4(20),11-dien-9-one (8), and 2alpha,5alpha-dihydroxy-7beta,10beta, 13alpha-triacetoxy-2(3-->20)abeotaxa-4(20),11-dien-9-one (9), on the basis of 1D and 2D NMR spectroscopic analysis. Compound 1, as a new compound isolated from T. chinensis var. mairei, is a rare example of a taxane with a 4,11-diene unit, which is considered to be an important intermediate in the biogenesis of taxoids. Compounds 2-4, 6, and 7 are new compounds, isolated from T. yunnanensis, which also afforded the known compounds 5, 8, and 9.

The roots of T. x media Rehd. cv. Hicksii gave three novel analogues of paclitaxel modified at the N-acyl residue (N-debenzoyl-N-alpha-methylbutyryl paclitaxel and N-debenzoyl-N-cinnamoyl paclitaxel, 1b and 1c, respectively) or at the ester group at C-2 (2-debenzoyl-2-tigloyl paclitaxel, 1d). Compounds 1b and 1d showed reduced cytotoxicity and tubulin binding compared to paclitaxel, while 1c retained substantial activity in these assays.

Three novel (1-3) and five known bicyclic 3,8-secotaxane diterpenoids were isolated from the needles of the Chinese yew, Taxus chinensis var. mairei. The structures of the new compounds were established, respectively, as (3E,7E)-2alpha,10beta, 13alpha-triacetoxy-5alpha,20-dihydroxy-3,8-secotaxa-3,7, 11-trien-9-one (1), (3E,7E)-2alpha,10beta-diacetoxy-5alpha,13alpha, 20-trihydroxy-3,8-secotaxa-3,7,11-trien-9-one (2), and (3E,8E)-7beta, 9,10beta,13alpha,20-pentaacetoxy-3,8-secotaxa-3,8,11-triene-2alpha, 5alpha-diol (2-deacetyltaxachitriene A) (3), on the basis of spectral analysis. The other five bicyclic taxane diterpenoids were determined as canadensene, 5-deacetyltaxachitriene B, taxachitriene B, taxuspine U, and taxuspine X by comparison of their physical properties and spectral data with those previously reported.

Fungi present in the inner bark of the yew tree Taxus yunnanensis were studied for the capability to biotransform natural taxoids. On the basis of screening, three fungi, Microsphaeropsis onychiuri, Mucor sp. and Alternaria alternata, were revealed to be able to selectively hydrolyze and epimerize two taxoids, 10-deacetyl-7-epitaxol (1) and 1β-hydroxybaccatin I (2), previously isolated from the bark of the same yew species. After preparative-scale incubation of 10-deacetyl-7-epitaxol with M. onychiuri and Mucor sp., three metabolites were isolated and characterized as 10-deacetylbaccatin V (3), 10-deacetyltaxol (4), and 10-deacetylbaccatin III (5). Incubation of 1β-hydroxybaccatin I with A. alternata, on the other hand, gave 5-deacetyl-1β-hydroxybaccatin I (6), 13-deacetyl-1β-hydroxybaccatin I (7), and 5,13-dideacetyl-1β-hydroxybaccatin I (8).

Two diastereomeric 2",3"-dibromo cephalomannines and their two corresponding 7-epimers were obtained by treatment of extracts of Taxus yunnanensis with bromine solution under mild conditions. Treatment of the same extract with chlorine solution yielded four diasteromeric 2",3"-dichlorocephalomannines, with no 7-epimers. The diastereomeric mixtures were separated into the individual components by preparative HPLC on C18 reversed-phase silica gel. A more efficient analytical separation was obtained on a pentafluorophenyl-bonded phase. These reaction products were isolated and fully identified spectroscopically. Slight differences were observed in the NMR spectra of the 7-epimers when compared to their 7 beta-OH analogues. On the basis of a comparison of physicochemical data, the bromo compounds were identified as (2"R,3"S)-dibromo-7-epi-cephalomannine (3), (2"S,3"R)-dibromo-7-epi-cephalomannine (4), (2"R,3"S)-dibromocephalomannine (5), and (2"S,3"R)-dibromocephalomannine (6), and the chloro compounds as (2"R,3"R)-dichlorocephalomannine (7), (2"S,3"S)-dichlorocephalomannine (8), (2"R,3"S)-dichlorocephalomannine (9), and (2"S,3"R)-dichlorocephalomannine (10). Cytotoxic activity was tested against the NCI 60 human tumor cell line panel in comparison with paclitaxel (1), and encouraging results were obtained in some cases.

Bioassay-guided fractionation of an extract of foliage of European yew (Taxus baccata L.) yielded two new (1−2) and a previously reported (3) taxoid that acted as pyrethroid insecticide synergists ...

Two new taxoids, taxezopidines M (1) and N (2), have been isolated from seeds of the Japanese yew, Taxus cuspidata, and new structures were elucidated on the basis of spectroscopic data. The absolute configuration of a 3-N,N-(dimethylamino)-3-phenylpropanoyl group in 1 and 2 was determined to be R in each case by chiral HPLC analysis. The effect of 1 and 2 on the CaCl(2)-induced depolymerization of microtubules was investigated.

The separation of a stem-bark extract of Taxus baccata L. cv. stricta by HSCCC resulted in several chromatographic fractions that were analyzed by ELISA using specific anti-10-deacetylbaccatin III antibodies. In addition to 10-deacetylbaccatin III and to four known xylosyl taxoids, a new taxoid, 9-deacetyl-9-benzoyl-10-debenzoyltaxchinin A (1), was isolated, and its structure was elucidated using spectroscopic methods. The cross-reactivity of 1 with anti-10-deacetylbaccatin III antibodies was examined.

The in vitro synthesis of secondary compounds from plants is one source of scarce and valuable phytopharmaceuticals. Often, some level of cellular or tissue differentiation is needed for the biosynthesis of many of these important compounds. Nodule cultures, consisting of cohesive multicellular units displaying a high degree of differentiation, were initiated from cultured needles of seven Taxus cultivars (Taxus cuspidata, Taxus x media 'Hicksii', Taxus x hunnewelliana 'Richard Horsey', Taxus x media 'Dark Green Spreader', Taxus x media 'L. C. Bobbick', and Taxus brevifolia). Under normal semicontinuous perfusion culture conditions (bimonthly refreshments to yield 0.2% sucrose), only trace amounts of taxol were detected from Taxus nodule cultures. However, with an elevated sucrose level (0.5% or 1.0%), taxol production was enhanced in T. cuspidata nodules to approximately 12 micrograms taxol/g nodule dry weight (dw). Stimulation of taxol production by elevated sucrose levels occurred even in the absence of other nutrients. The effect of increased sucrose on taxol induction does not appear to be due to an osmotic effect in the medium, suggesting that the increase in taxol production may be correlated with a metabolic process within the nodules. Although sucrose had a significant effect on taxol production, taxane precursors or elicitors of terpenes, as well as other plant secondary metabolites, had no effect on the production of taxol from these cultures. In addition to taxol, the higher sucrose levels also induced the production of 7-epi-10-deacetyltaxol, cephalomannine, and 7-epi-10-deacetylcephalomannine, so that total content of these taxanes equaled approximately 39 micrograms taxane/g dw nodules.

Three new 14beta-benzoyloxy taxoids containing an oxetane ring, namely, 14beta-benzoyloxybaccatin IV (1), 14beta-benzoyloxy-13-deacetylbaccatin IV (2), and 14beta-benzoyloxy-2-deacetylbaccatin VI (3), have been isolated from the leaves and stems of Taxus chinensis. Their structures were elucidated on the basis of 1D and 2D NMR spectroscopic data.

Two new fusicoccane diterpenes, named periconicins A (1) and B (2), with antibacterial activities have been isolated by bioassay-guided fractionation from an endophytic fungus Periconia sp., collected from small branches of Taxus cuspidata. The structures of the new compounds were determined by combined spectroscopic methods.

Four new taxanes were isolated from the roots of Taxus yunnanensis. Among them, two were determined to contain isobutyrate group and propionyloxy group on C-14 respectively, and one was determined as the least oxygenated taxane. The structures were elucidated by spectroscopic means.

Polyclonal antibodies raised against 2'-succinyltaxol-bovine serum albumin (BSA) conjugate were used for the immunodetection of bioactive taxoids in chromatographic fractions of the stem bark extract of Taxus baccata. In addition to taxol, cephalomannine, and baccatin III, two taxoids were isolated and their structures were elucidated as 4 alpha,7 beta-diacetoxy-2 alpha,9 alpha-dibenzoxy-5 beta,20-epoxy-10 beta, 13 alpha, 15-trihydroxy-11(15-->1)-abeo-tax-11-ene[5] and taxol C [6] using spectroscopic methods.

Yunantaxusin A [2], an 11(15-->1)abeo-taxane-type diterpene with an opened oxetane ring, has been isolated from the leaves and stems of Taxus yunnanensis. Its structure was established from its spectral data.

The taxol content of dried Taxus biomass was monitored monthly for 15 months. Intact and finely ground biomass was stored at room temperature (22 degrees-24 degrees) as well as under refrigeration (2 degrees-4 degrees). In addition, intact fresh clippings stored under refrigeration in sealed plastic bags for up to 10 weeks were evaluated for changes in taxol content. Analysis indicates that properly dried Taxus clippings can be stored either intact or powdered at room temperature or under refrigeration with no apparent loss of taxol content. The taxol content in fresh intact clippings was also stable for at least 10 weeks when stored under refrigeration.

Four new taxoids were isolated from cell cultures of Taxus baccata. Their structures were elucidated by spectroscopic analyses. Two were the aglycones corresponding to previously isolated 7-O-xylosides of taxol C [1] and 10-deacetyltaxol C [2]. The third [3] had an N-methylated side-chain, while the fourth, named taxcultine [4], contained an n-propyl group on the side-chain. All four compounds actively promoted tubulin assembly. Taxol C [1] showed potent and selective cytotoxicity in the NCI human cell line screen.

Five new diterpenoids, taxchinins A {3}, B{4}, and C{5}, 19-hydroxy-7-epibaccatin III {6}, and 10-deacetyl-10-oxobaccatin V {7}, have been isolated from the needles and stems of Taxus chinensis together with twelve known compounds including taxol {1}. These structures were elucidated and identified by spectroscopic techniques. A single X-ray crystallographic analysis of taxchinin A {3} determined its unique 51716-membered ring system. Taxchinins B {4} and C {5} were shown to have the same ring system

The seeds of the European yew, Taxus baccata, gave two alkaloidal taxanes 2 and 4, related to taxine B [1], and an oxygenated derivative 5 of brevifoliol. Conformational flexibility of the tricyclic taxane skeleton was detected in 5

Three new 11(15-->1)-abeo-taxanes, taxumairols U-W (1-3), have been isolated from extracts of the stem bark of Formosan Taxus mairei. The structures of 1-3 were identified as 5alpha,7beta,9alpha,13alpha,20-pentaacetoxy-2alpha,10beta,15-trihydroxy-11(15-->1)-abeo-taxene, 5alpha,7beta,9alpha,20-tetraacetoxy-2alpha,10beta,13alpha,15-tetrahydroxy-11(15-->1)-abeo-taxene, and 2alpha,4alpha,7beta,10beta-tetraacetoxy-5beta,20-epoxy-9alpha,13alpha,15-trihydroxy-11(15-->1)-abeo-taxene, respectively, on the basis of 2D NMR techniques including COSY, HSQC, HMBC, and NOESY experiments as well as chemical reactions of compounds 1-3 to give 4 (5alpha,7beta,9alpha,10beta,13alpha,20-hexaacetoxy-2alpha,15-dihydroxy-11(15-->1)-abeo-taxene) and 5 (4alpha,7beta,10beta-triacetoxy-9alpha,13alpha-dibenzoxy-5beta,20-epoxy-2alpha,15-dihydroxy-11(15-->1)-abeo-taxene), which are also novel taxane derivatives. Taxumairols U (1) and V (2) exhibited significant cytotoxicities against human hepatoma tumor cells, while taxumairol W (3) was inactive.

Two site-directed mutations within the wild-type 2-O-benzoyltransferase (tbt) cDNA, from Taxus cuspidata plants, yielded an encoded protein containing replacement amino acids at Q19P and N23K that map to a solvent-exposed loop region. The likely significant changes in the biophysical properties invoked by these mutations caused the overexpressed, modified TBT (mTBT) to partition into the soluble enzyme fraction about 5-fold greater than the wild-type enzyme. Sufficient protein could now be acquired to examine the scope of the substrate specificity of mTBT by incubation with 7,13-O,O-diacetyl-2-O-debenzoylbaccatin III that was mixed individually with various substituted benzoyls, alkanoyls, and (E)-butenoyl CoA donors. The mTBT catalyzed the conversion of each 7,13-O,O-diacetyl-2-O-debenzoylbaccatin III to several 7,13-O,O-diacetyl-2-O-acyl-2-O-debenzoylbaccatin III analogues. The relative catalytic efficiency of mTBT with the 7,13-O,O-diacetyl-2-O-debenzoyl surrogate substrate and heterole carbonyl CoA substrates was slightly greater than with the natural aroyl substrate benzoyl CoA, while substituted benzoyl CoA thioesters were less productive. Short-chain hydrocarbon carbonyl and cyclohexanoyl CoA thioesters were also productive, where C(4) substrates were transferred by mTBT with approximately 10- to 17-fold greater catalytic efficiency compared to the transfer of benzoyl. The described broad specificity of mTBT suggests that a plethora of 2-O-acyl variants of the antimitotic paclitaxel can be assembled through biocatalytic sequences.

The investigation of Taxus canadensis (Canada yew) needles as a renewable source of taxol and its congeners led to the isolation of a novel taxane derivative, 9-dihydro-13-acetylbaccatin III [1], which was characterized by spectral analyses and confirmed by single crystal X-ray diffraction studies

Taxol and cephalomannine concentrations were measured in the bark and foliage of Pacific yew trees growing in the shade of a forest canopy and at a site nearby where trees had been exposed to full sunlight for 6 years. Bark was the only tissue showing concentration differences due to light, with significantly greater quantities of both compounds in the bark of shaded trees than in the bark of sun-exposed trees. In either light regimen taxol concentrations were greater in the bark than in the needles or twigs

International audience; The structure of taxine B, the main alkaloid of leaves of European yew, Taxus baccata, has been revised by means of ‘H detected multiple bond heteronuclear multiple quantum coherence (HMBC) experiment.

Paclitaxel is an effective antineoplastic agent originally extracted in low yield from the bark of Taxus brevifolia. Although it was generally considered a particular metabolite of Taxus sp., paclitaxel was recently found in hazel cell cultures. The aim of the present work was to verify whether hazel differentiated tissues could be used as a commercial source of paclitaxel and other taxanes. Thus, shells and leaves of hazel plants were analyzed by ELISA and HPLC-MS. Both shell and leaf extracts contained taxanes. Among these, paclitaxel, 10-deacetylbaccatin III, baccatin III, paclitaxel C, and 7-epipaclitaxel were identified and quantified. Hazel extracts also showed biological activity, inhibiting metaphase to anaphase transition in a human tumor cell line. The level of total taxanes in leaves was higher than in shells collected in the same period from the same plants. However, the finding of these compounds in shells, which are considered discarded material and are mass produced by many food industries, is of interest for the future availability of paclitaxel and other antineoplastic compounds.

In this review we will briefly summarize our earlier published studies of taxol analogues, and then present some new and as-yet-unpublished work on the preparation of some novel derivatives of taxol and baccatin III

Quantitative 1H NMR (qHNMR) provides a value-added dimension to the standard spectroscopic data set involved in structure analysis, especially when analyzing bioactive molecules and elucidating new natural products. The qHNMR method can be integrated into any routine qualitative workflow without much additional effort by simply establishing quantitative conditions for the standard solution 1H NMR experiments. Moreover, examination of different chemical lots of taxol (paclitaxel) and a Taxus brevifolia extract as working examples led to a blueprint for a generic approach to performing a routinely practiced 13C-decoupled qHNMR experiment and for recognizing its potential and main limitations. The proposed protocol is based on a newly assembled 13C GARP broadband decoupled proton acquisition sequence that reduces spectroscopic complexity by removal of carbon satellites. The method is capable of providing qualitative and quantitative NMR data simultaneously and covers various analytes from pure compounds to complex mixtures such as metabolomes. Due to a routinely achievable dynamic range of 300:1 (0.3%) or better, qHNMR qualifies for applications ranging from reference standards to biologically active compounds to metabolome analysis. Providing a "cookbook" approach to qHNMR, acquisition conditions are described that can be adapted for contemporary NMR spectrometers of all major manufacturers.

Two new taxoids, 13,15-epoxy-13-epi-taxayunnasin A (1) and taxchinin N (2), were isolated from the leaves and stems of Taxus chinensis. Compound 2 is the first taxoid to be reported with an alpha,beta-unsaturated lactone at C-4, C-5, C-20, and C-2. The structure of 1 was elucidated by spectroscopic analysis and confirmed by semisynthesis from taxayunnasin A, while 2 was determined structurally using spectroscopic methods and by single-crystal X-ray diffraction.

Investigation of the bioactive compounds from a Penicillium sp. isolated from the inner bark of the Pacific yew, Taxus brevifolia, led to the isolation of the known furanone 1, and a series of phomopsolides. The phomopsolide fractions contained phomopsolides A and B, which have previously been described, and three new phomopsolides. The structures of the new phomopsolides were deduced by comparison of their NMR spectra to those of the known compounds.

Seventeen known taxoids and 10 abietanes were isolated from the dark brown callus culture of Taxus cuspidata cultivated on a modified Gamborg's B5 medium with 0.5 or 1.0 mg/L NAA. Seven known taxoids and four abietanes were obtained from the callus culture incubated under light irradiation on the medium with 1.0 mg/L NAA. Eight taxoids and five abietanes were also separated from the callus culture on the medium with 10 mmol/L beta-cyclodextrin and 1.0 mg/L NAA. The new compounds were identified by analyses of the spectroscopic data and were found to be abieta-6,8,11,13-tetraene-3beta,12-diol (1), 3beta,20-epoxy-12-methoxy-abieta-8,11,13-triene-3alpha,11-diol (2), 3alpha-hydroxy-9(10--20)abeo-abieta-1,5,8,10(20),13-pentaene-7,11,12-trione (3), 2-hydroxy-9(10--20)abeo-abieta-1,5,8,10(20),13-pentaene-3,7,11,12-tetraone (4), and 3,7-dioxo-9(10--20)abeo-12-norabieta-1,5,8,10(20),13-pentaene-11,13-lactone (5), respectively. The yield of paclitaxel and its analogues was markedly decreased in the calluses mentioned above compared with that of standard callus. Instead, abietanes and some taxoids related to biosynthesis of paclitaxel were produced. Taxusin (6) exhibited stronger MDR-reversing activity than verapamil toward 2780 AD tumor cells.

A new 11(15→1)-abeotaxane diterpene, 7,9-dideacetyltaxayuntin (1), and 11 known taxane diterpenes were isolated from the bark of Taxus yunnanensis. Their structures were determined primarily on the basis of analysis of their 1 H NMR, 13 C NMR, DEFT, 1 H- 1 H COSY, HMQC, HMBC, and mass spectra.

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.

Brevifoliol is a natural diterpene isolated from Taxus baccata Nutt. A series of brevifoliol 1 derivatives, 2-8 and 10, were prepared for characterization and semisynthesis purposes and included the introduction of acetyl, Troc, and TES groups at C-5 and C-13. Derivatives 16-20 of 5-acetylbrevifoliol 2 were obtained via esterification with cinnamic acid, with both 2S-(-)- and 2R-(+)-3-phenyllactic acid, and with N-benzoyl-(2'R,3'S)-3'-phenylisoserine at C-13. Brevifoliol compounds 12, 13, and 15 with either 2S-(-)-phenyllactate moieties at C-5 and C-13 or an N-benzoyl-(2'R,3'S)-3'-phenylisoserinyl at C-13 were also prepared. An abeo-taxane structure for 1 was clearly defined from the (13)C NMR analysis of the 5-acetyl-13-oxo derivative 8 and from the conversion of 1 into 10, a conformationally restrained compound having a C-13, C-15 oxygen bridge. The biological activity of each of these derivatives is being studied.

Five new taxanes, 5alpha,9alpha,10beta,13alpha-tetraacetoxy-14beta-O-(beta-d-glucopyranosyl)taxa-4(20),11-diene (1), 1beta,2alpha,9alpha,10beta-tetrahydroxy-5alpha-cinnamoyoxytaxa-4(20),11-dien-13-one (2), 2alpha,9alpha,10beta-trihydroxy-5alpha-cinnamoyoxytaxa-4(20),11-dien-13-one (3), 9alpha-acetoxy-2alpha,10beta-dihydroxy-5alpha-cinnamoyoxytaxa-4(20),11-dien-13-one (4), and 2alpha,10beta-diacetoxy-1beta,9alpha-dihydroxy-5alpha-cinnamoyoxy-3,11-cyclotaxa-4(20)-dien-13-one (5), have been identified in a Taxus baccata yew grown in Israel from seeds imported from the United States. We have also characterized 40 previously known taxanes from this plant material. The structures of the new taxanes (1-5) were rigorously established with 1D and 2D NMR data and confirmed by high-resolution FAB-mass spectrometry.

All of us who have worked with taxol in the laboratory and the clinic, and the many patients all over the world who have benefited from the drug, owe a great debt of gratitude to Monroe Wall, Mansukh Wani, and their colleagues for the initial isolation and characterization of this compound.