Seasonal variation of neutral and basic taxoid contents in shoots of European Yew (Taxus baccata)

Seasonal variations of taxoid constituents were determined in shoots of Eur opean Yew collected from two locations. The first samples originated from a male Taxus baccata tree growing in Gif, France. The second samples were ob tained from genetically identical female Irish Yew trees (T. baccata var. f astigiata), of the same age and growing at one site in Dublin, Ireland. Sho ots were collected monthly for one year and separated into needles and stem s. Neutral taxoids (paclitaxel and 10-deacetylbaccatin III (10-DAB III)) an d basic taxoids (including taxines B) were extracted and quantified. Needle s yielded significantly higher levels of taxoids than stems. 10-DAB III con tents in needles of French samples showed considerable monthly fluctuations , while in needles of the Irish samples maximum yields of 10-DAB III were f ound in June. Highest levels of paclitaxel were present between February an d April. Basic taxoids occurred in highest concentrations (total alkaloids 9.49 g/kg) in the August collection of French samples, but in needles of th e Irish Yew in November and December (total alkaloids 16.9 g/kg; taxines B 10.9 g/kg). No conclusion could be drawn as to the optimum time of year for harvesting, since this varies from tree to tree, depending on T. baccata v ariety, location and taxoid type. (C) 1999 Elsevier Science Ltd. All rights reserved.