is not poisonous. There has been confusion over this
issue for two reasons, both of which will be clarified here.
Pacific Northwest of the United States has actually only
been ‘civilized’ and ‘settled’ for a little over 100 years.
Most of the people that ‘settled’ this country were of
European or Asian decent. They recognized the yews when
they got here and mistakenly assumed they were poisonous
like the yews in their homelands.
European yews (Taxus baccata) and Japanese yews
(Taxus cuspidata) are
poisonous because they contain toxic
amounts of the cardiotoxic alkalodial
fraction named ‘taxine’.
Taxus brevifolia got a bad rap due to
guilt-by-association and that is why many
websites, encyclopedias and botanical publications list
Taxus brevifolia as
There are no documented
instances of poisoning in humans or animals with
cardiotoxic alkaloidal fraction ‘taxine’ is relatively
abundant in Taxus baccata (European Yew) and
even more so in Taxus cuspidata (Japanese Yew), which
are the most frequent causes of stock poisonings by yew, but
the taxine fraction is almost absent in Taxus
brevifolia, and Pacific Yew is indeed a frequent browse
of moose, elk and deer.” (Suffness (1995), Taxol Science
and Applications, page 8).
chemical studies of the toxicity of yew indicated that the
major toxicity was due to ‘taxine’, which is now
known to be a mixture of alkaloids with
and taxine B as the major constituents. Taxine
causes death from asphyxia due to cardiac and
respiratory failure.” (Suffness (1995), Taxol Science
and Applications, chapter 12, The Toxic
Constituents of Yew, page 311).
Due to an
idiosyncrasy of nature, Taxus brevifolia is lacking
in harmful amounts of poisonous alkaloids as documented by
V.E.Tyler, Jr. (1960).
the Occurrence of Taxine in Taxus brevifolia”. Journal
of the American Pharmaceutical Association Scientific
Edition, Vol. 49, No. 10,
yield from fresh needles of Taxus brevifolia,
analyzed by Tyler, showed
fresh weight, and “cyanogenetic glycosides of this type were
found to be absent in this alkaloid-poor species.”
Product Safety Labs – Chicago, IL.
Acute Oral Toxicity Study in
Rats – Limit Test (Summary)
Purpose – to provide information on health
hazards likely to arise from a short term exposure to
Montana YewTip™ Powder (Taxus brevifolia) by the oral
Procedure – Each animal received 5,000 mg/kg
of the test substance, as 25% ww suspension in distilled
water by intubation. The animals were observed for
mortality, signs of gross toxicity and behavorial changes at
least once daily for 14 days. Body weights were recorded
prior to initiation and at termination.
Results – All animals survived, gained weight
and appeared active and
healthy. There were no signs of gross toxicity, adverse
Conclusion – The single dose acute oral LD 50
of Montana YewTip™ Powder
brevifolia) is greater than 5,000 mg/kg of body
Test Method Number
Study Number – 7734
Sponsor – Trimedica,
Inc, Tempe, AZ
Test Substance –
Montana YewTip™ Powder (Taxus brevifolia)
Decription – dark green powder
PSL Reference Number –
Dates of Test – June
Notebook Number –
99-38, pages 222-227
Another confusing issue regarding toxicity of
Taxus brevifolia is also a case of
‘guilt-by-association’. Adverse effects of
chemotherapeutic drugs produced from Taxus brevifolia
(Taxol) and Taxus baccata (Paclitaxel) are different
than herbal preparations of Taxus brevifolia.
ethanol:Cremophor vehicle required to solubilize paclitaxel
in Taxol is toxic. Although it has been used to
administer other drugs, such as cyclosporine
the amount of Cremophor necessary to deliver the required
doses of Taxol is significantly higher than that
administered with any other marketed drug. Thus the
vehicle has been shown to cause serious or fatal
hypersensitivity episodes at nearly every step in the
developmental path, in both preclinical and clinical
testing. One mediator of the hypersensitivity reaction is
endogenous histamine release, and prophylaxis to counteract
histaminergic mechanisms reduce the incidence of
(1995), Taxol Science and Applications, Chapter 9,
is polyethoxylated castor oil.
toxic side effects have been attributed to Taxol
(Paclitaxel), including cardiotoxicity, neutropenia,
peripheral neuropathy, mucositis, gastrointestinal
toxicities, alopecia, arthralgias and myalgias.
Attributes of Taxus brevifolia by Maria Costello and
Kelly Kellmell (1997).
(Paclitaxel) is administered intravenously with
pre-treatment with other drugs to counter the adverse