New Taxanes from Taxus chinensis

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.

Isolation and identification of two new compounds from the twigs and leaves of Cephalotaxus fortunei

Two new compounds, namely 5-hydroxy-7-methoxy-6-methylchromone (1), and sesquiterpene X (6), together with 21 known compounds were isolated from the twigs and leaves of Cephalotaxus fortunei Hook. f. The structures of 1-23 were elucidated on the basis of spectroscopic analysis (1D/2D NMR, HR-ESI-MS and IR) and comparison with literature. The absolute configuration of compound 6 was determined by means of electronic circular dichroism calculation. The in vitro anti-inflammatory activities of all compounds were assayed in RAW 264.7 cells by assessing lipopolysaccharide-induced nitric oxide production. Compounds 1 and 6 exhibited weak effects with percentage inhibitions of 24% and 35.60%, respectively. In addition, compounds 4, 9, and 14 have the potential to be developed as therapeutic agents for inflammatory diseases because of their significant anti-inflammatory activities and high content in C. fortunei.

Taxanes in rooted cuttings vs. mature Japanese yew

Two novel taxanes were identified from rooted cuttings of the Japanese yew, Taxus cuspidata Sieb. et Zucc. Their structures were characterized as taxa-4(20),11-dien-2α,5α-diacetate-14β-(2'S,3'R)-3'-hydroxy-2'-methylbutyrate-10-β-glucoside (1) and 2α,5α,9α,10β-tetraacetoxy-13α-(Z)-cinnamoyloxy-taxa-4(20),11-diene (2). In addition, metabolites 3–43 were also characterized in the same cuttings. Taxanes 3–16 as well as three non-taxane metabolites (17–19) have not previously been reported in the needles, stems, seeds, or bark of the mature T. cuspidata plant, although they have been found in other yews. The known taxanes 20–43 were also detected for the first time in the rooted cuttings of the Japanese yew. Key words: Taxus cuspidata, Taxacae, taxanes, rooted cuttings, metabolites.

Taxus canadensis taxanes: structures and stereochemistry

The structures and stereochemistry of 14 taxanes isolated from Taxuscanadensis have been rigorously established by high-resolution NMR techniques and mass spectrometry. Taxuscanadensis is the only yew that accumulates 9-dihydro-13-acetylbaccatin III (also called 7,9-deacetylbaccatin VI) as the most abundant taxane. Five 9-dihydrotaxanes derived from the Canadian yew are novel natural products not reported in the needles of other species of yew (8–11, 14, Fig. 1). Keywords: Taxuscanadensis, Taxaceae, taxanes, 9-dihydro-13-acetylbaccatin III, taxol.