| Some observations and conclusions reached after years of study
and research.
The original, written in 1997, has been edited for this article.
The Hampton Court Yews
The fact that several old yews at Hampton Court have been felled
in recent years is a sad indictment that we appear to be more
pre-occupied with formal garden design rather than seeing and
appreciating the special presence of these 300 year old trees.
They are after all trees which offer us a renewable source of
a substance already of immense medicinal value, extracted chiefly
from its evergreen needles. From this extract comes the ingredient
called ‘taxol’. I would like to consider how I believe
it might have even greater potential.
The use of taxol in drug form against certain kinds of cancer
was, from its earliest trials, heralded as one of the biggest
breakthroughs to date in the fight against cancer, because of
the unique properties which it possesses, and the way these can
be utilised to combat the disease. I believe that taxol/taxotere
could be made to be even more effective than it is so long as
more attention is paid to its point of origin, the yew tree.
We know that clippings from the Hampton Court Yews have already
been used along with those from many other sources to help many
hundreds of cancer patients. However it is my opinion that we
need to be clear about the exact location of the batches of clipping
that are used. At Hampton Court there are also avenues of yews,
which are more important a source of origin than a yew hedge or
maze. This is because yews in an avenue can be more readily identified
as being female or male and, if it is not already becoming apparent
in taxol research, it will become increasingly important to separate
clippings into their gender origin. At present such attention
is not given in the collection of clippings and if gathered from
hedges or mazes, which are also to be found at Hampton Court,
then the task of establishing gender is extremely difficult as
both sexes of the yew grow so close to each other in such environments.
Thus the yew avenue offers a better chance of gender selection
at the outset and consequently vastly improves further research
potential.
It is quite clear to me therefore that the chances of making
future breakthroughs in Taxol research and treatment require the
proper protection and registration of all yew avenues like Hampton
Court.
Seasonal Variation Factors.
I have considered the need for the selection of yew needles
by gender, for which a limited amount of work has already been
done. This is also the case when considering how seasonal variation
factors influence Taxol yields. (Griffin and Hook) It is surely
time to look at the adequate funding of research possibilities
which take into account the following criteria:
Examples:
Species - e.g. Taxus baccata
Gender - e.g. female
Estimated age - e.g. 300 years ( as in the case
of Hampton Court ).
Month and season - e.g. late February, spring.
Conditions - e.g. wet or dry and if these conditions
had been prevalent for some notable period previously, say three
days at least, and especially if this was typically unseasonal.
Temperature - e.g. very cold, cold, mild, warm
and hot and again note if these conditions had been prevalent
for a noticeable period or were unusual.
Colour of needles - e.g. light green/dark green.
Specifically targeted methods of collection could also be used
by for instance specifying spring collection from the male and
summer for the female, thus they are gathered separately.
“The yew poison may be of moderate virulence only, and
may occur in greater percentage in male than in female trees,
or the percentage may vary from tree to tree without distinction
of sex, and this may explain the capricious occurrence of poisoning……….also
the half-dried leaves would be, ceteris paribus, more potent than
the fresh. From an article “Variation in Taxol Content”
by Professor Munro, published in the Journal of the Royal Agricultural
Society 1892. Further details also in John Lowe’s The
Yew Trees of Great Britain and Ireland.
We already know that there can be marked differences in taxol
yield between sub species of the yew tree e.g. between taxus
baccata and fastigiata, (Colin Morgan – Bedgebury
Pinetum) but it is not yet so apparent that the yields are affected
by seasonal and gender factors within each sub-species.
Furthermore it is becoming increasingly recognised that even
individual yews might have unique chemical characteristics contained
within the needle, aril, flower or trunk. After seeing thousands
of Taxus baccata it becomes quite clear that the colour of the
needles, the size of the berry, and the colour and character of
trunk can all be quite different. These things may not appear
to be so relevant now, but they could hold the minute difference
between an extra year of life and a possible cure. Therefore during
the course of any research we must respect and safeguard the future
of this ‘Tree of Life’.
Identification - D.N.A. and ancestry
Very few areas of ancient yew wood remain anywhere in the world.
Britain is the last main refuge for these trees. Therefore it
is here that identification and tracking origins could be crucial.
Most of the trees for example at Druid’s Grove or Newlands
Corner may have originated from one or two trees - the parent
trees. Natural layering by one or two yews could, over the centuries,
create a wood or forest. A line of descent could be traced through
DNA sampling to discover the ancestry of any yew. Hundreds of
trees in the same forest might have shared the same D.N.A. in
their wood for thousands of years. These origins might one day
prove to be of importance in the development of life saving drugs.
Concentrations and strengths of yields are probably uppermost
in the eyes of scientists but subtle differences in inherent qualities,
as found in grape varieties for wine production, will probably
reveal themselves to be of paramount importance. In looking more
closely at the properties of the yew we should be prepared to
consider all possibilities and rule none out at this point. We
may have only taken the very first steps in recognising the potential
of Taxol.
Planning for the Future.
I have tried to establish the importance of knowing as much
detail as possible about the origin of the batches of needles
used in research and to make taxol. If a particular yew, or group
of yews, prove to have specific qualities that are beneficial
then it is especially important to preserve those trees and preserve
the line of descent through a planting programme taken from cuttings
from individual trees.
The Conservation Foundation’s Millenium Yew planting programme
which has taken cuttings from yews thought to be 2000 years old
to eventually be placed in over 13000 parishes in Britain may
be inadvertently activating one of the most important schemes
of the new century as it will help to ensure the continuation
of an ancient yew ancestry.
To safeguard our remaining especially ancient yews, we must not
only protect them now but set up nurseries and plantations in
areas where cuttings from the remaining yews can be maintained
and propagated. The yews of ancient status which have survived
this long should, it goes without saying, be protected by law.
There is no doubt that the yew contains a very powerful drug
and we have to use it wisely and acknowledge where it comes from.
Additional notes :
Berries and seeds - how much attention has been paid to the
healing qualities of the yew’s fruit, the red aril, and
the seed therein rather than just the leaves and bark? Although
very highly toxic, (indeed fatal if ingested) as the seed is,
as well as the bark and leaves, the flesh of the surrounding fruit
is not; but extreme caution is advised if the intention is to
eat them, as the effects from consuming them can vary considerably
from tree to tree, are not as yet properly understood and best
avoided except under the most expert knowledge and supervision.
Fungi on the yew.
It would be an interesting exercise to examine the healing potential
of the Yellow Sulphur Polypore, Laetiporus Sulphureus,
as this is a very common fungus found on the yew, as well as the
willow and the ash, which may well take on some of the properties
of its host. Although sometimes cooked and eaten, second thoughts
should perhaps be given to this intention if it is found growing
on a yew. Its most potentially interesting stage however is when
the bright yellow - orange stages of adolescent growth have paled
as the fruit dries to an off-whitish colour. It is at this stage
that it could be most potent concerning its medicinal properties.
These dry brackets of this particular polypore could easily be
reduced to powder form which investigative yew science may find
to be of significant interest.
If amounts of Taxol are absorbed into the fungi, this may give
an indicator in how to produce a soluble form of Taxol which could
be directly administered to the patient. Probably natural quantities
might not be suffcient but the equation of synthetic production
might come in at this stage (see early reference to fungi in The
Sacred Yew , p 234).
Copyright © A.Meredith 2002 All Rights Reserved
References :
Chetan A. & Brueton D. (1994) - The
Sacred Yew, Penguin Arkana.
Griffin J. & Hook I. (1996 ) - Taxol
Content of Irish Yews, PLANTA MEDICA, pp 370 - 372 Num62
.
Tabbush, P. & White, J. (1996 ) - Ancient
Yew Woodand, Quarterly Journal of Forestry Vol 90 No.3 pp
197 - 206.
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