A new taxane with an amino side chain on C-5 and a new 11(15→1)abeotaxane having a tetrahydrofuran ring along carbon atoms C-2, C-3, C-4, C-20 identified for the first time from the needles of the Canadian yew, Taxus canadensis. Their structures were characterized as 2α,7β ,9α,10β ,13-pentaacetoxy-11β -hydroxy-5α-(2´ -hydroxy,3'-N,N-dimethylamino-3´- phenyl)-propionyloxytaxa-4(20),12-diene (1) and 13α,20β -diacetoxy-5α,7β ,9α,10β -tetrahydroxy- 2α,20-epoxy-11(15→1)abeotaxa-11,15-diene (2) on the basis of 1D, 2D NMR spectroscopy and high-resolution FABMS analysis. Taxane 1 contains a rare C-12, C-13 double bond and a basic side chain, while taxane 2 bears a rare isopropenyl group at C-1.
Structural modifications were performed on isoalantolactone in an effort to find compounds with potential anticancer activity. Seven previously unknown adducts of active methylene compounds with isoalantolactone were synthesized by the Michael reaction. Moreover, four derivatives of aryl-substituted isoalantolactone were prepared by the Heck reaction. All synthetic products were evaluated for toxic activities against three different hepatoma cell lines, Bel-7402, SMMC-7721, and Hep G2. Products prepared through the Heck reaction and 3a,b show potential antiproliferative activity against the Hep G2 cell.
Two new phytoecdysteroids with a 20,22-acetal group were identified for the first time from the needles of the Canadian yew, Taxus canadensis. Their structures were characterized as ponasterone A 20,22-p-hydroxybenzylidene acetal (1) and ponasterone A 20,22-acetonide (2) on the basis of 1D, 2D NMR evidence and high-resolution FABMS analysis
Two minor taxane glycosides were isolated for the first time from the needles of Taxus canadensis. Their structures were characterized as 2α,5α-diacetoxy-10β-(6′-O-acetyl-β-d-glucopyranosyl)oxy-14β-[(2′R,3′S)-3′-hydroxy-2′-methylbutanoyl]oxytaxa-4(20),11-diene (1) and 2α,14β-diacetoxy-10β-(β-d-glucopyranosyl)oxytaxa-4(20),11-dien-5β-ol (2) on the basis of 1D and 2D NMR data analysis and confirmed by high-resolution fast atom bombardment mass spectrometry.
Two 11(15→1)abeotaxanes having a tetrahydrofuran ring along the carbon atoms C-2, C-3, C-4, C-20 were identified for the first time from the needles of the Canadian yew, Taxus canadensis. The compounds could be identified as 4α,10β,13α-triacetoxy-15-benzoyloxy-2α,20β- epoxy-11(15→1)abeotax-11-ene-5α,7β,9α-triol () and 4α,7β,9α,10β,15-pentaacetoxy-2α,20β- epoxy-11(15→1)abeotax-11-ene-5α,13α-diol (2) on the basis of 1D-, 2D-NMR evidence and high-resolution FABMS analysis. Compound 1 showed weak growth inhibitory activities against T-98 and MM1-CB cells in vitro.
Sinenxan H [2α,14β -diacetoxytaxa-4(20),11-diene-5α, 10β -diol, 1] was isolated from the heartwood of Taxus cuspidata, for the first time from natural sources. Compound 1 was found to be readily converted into 2α-acetoxytaxa-4(20),10,12(18),13-tetraen-5α-ol (2), the first example of a taxane with 10,11- and/or 13,14-double bond(s) and a conjugated triene system, in CDCl3.
A new taxane peroxide, 4α,10β,13α-acetoxy-2α-benzoyloxy-7β,9α-epidioxy-5β,20-epoxytax-11-en-1β-ol (1), was isolated and characterized for the first time in rooted cuttings of the Canadian yew, Taxus canadensis.
A novel 6/12-membered bicyclic taxane with a 13,17-ether bridge, named canataxpyran A, was isolated from the needles of Taxus canadensis. The structures were characterized as 7β,9,10β,20-tetracetoxy-13β,17-epoxy-3,8-secotaxa-3E,8E,11-triene-2α,5α-diol (designated as canataxpyran A, 1). This bicyclic taxane gradually decomposed in CDCl3to give the corresponding enones, 10β,20-diacetoxy-13β,17-epoxy-4α,5α-dihydroxy-3,8-secotaxa-2E,7E,11-trien-9-one (canataxpyran B, 2) and 5α,10β,20-triacetoxy-13β,17-epoxy-4α-hydroxy- 3,8-secotaxa-2E,7E,11-trien-9-one (canataxpyran C, 3). Compound 1 is the first example of a natural 3,8-secotaxane with 13,17-oxygen bridge.
Ten 1,10-secoguaianolides were isolated from the flowers of Achillea millefolium. Their structures were determined on the basis of spectroscopic methods. Three of them (millifolides A-C) including two dimeric sesquiterpenoids exhibit new skeletons. Seco-tanapartholide A exhibited moderate cell growth inhibitory activity against the human cancer cell line MCF7WT (IC50 = 5.51 μm) in vitro.