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- Loverly Duverly – exploring the duvers of the Isle of Wight - 19th July, 2020
Ages ago The Ranger worked for the National Trust in East Anglia. it was a remarkable and not unpleasant experience, a nice part of which was discovering much about the fine old houses that were a part of the Trust’s holdings out there – although as a humble nature reserve manager he only got to go to the posh houses when invited – and then he usually had to be reminded to take his boots off. One of the snippets that he picked up during this employment was a tale about yew trees. It was said that the clippings from the great hedges of yew on the landscaped estates were collected annually and sent off for medical research to make new cancer drugs.
These particular yews are beautifully managed by the Isle of Wight Council, not the National Trust.
For years after, The Ranger adorned his guided walks and interpretation leaflets with this snippet: yew trees make cancer drugs. But then he began to have doubts. The wonder of the internet allowed him to discover all about the marvellous story of the discovery of Taxol (Paclitaxel) in the bark of Pacific yews by American scientists in the 1960s. Maybe this had become a kind of urban myth and had mutated into this idea of stately English yews contributing their leaves? There are some elements of the story that just don’t add up. English yew is a different species from Pacific yew – and Taxol is made in laboratories and now not made directly from yew trees at all. So nobody would actually want English yew hedge clippings, would they? Was none of it true after all? He began to doubt the reliability of his oft-recounted truism. Now join The Ranger on a hunt through the internet to find the truth. Today once more The Ranger’s interest in this subject was awakened as a story in the Eastern Daily Press repeats the original story he heard, and suggests that actually, it is true. For decades the great yew hedges of England have indeed been contributing clippings to medical research, and continue to do so:
Harvesting the 300-year-old hedges for their health-giving properties has been going on for more than 20 years. The clippings are collected by Friendship Estates, who pass them to the drug industry, which isolates the taxol used to make drugs for battling breast and ovarian cancer. While most parts of yew trees are poisonous the taxol, from the inner bark, was discovered to be effective in halting cancer growth in some patients. It is injected into the tumour and captures the problems cells in a cage of miniature tubes. It takes the product of six trees to help one patient, but many stately homes, including Hampton Court, contribute to the clippings bank. Assistant gardener at Blickling Stephen Hagon said cutting of the hedges always generated a lot of interest from visitors, adding: “One year we had a lady who had visited the property, return with a shoe box of yew cuttings from her own garden. She wanted to do her bit.”
Credible as far as it goes – but not much detail. And some worrying confusion about the bark and the clippings – if it’s bark they want, why send them clippings? Maybe the EDP has just repeated the same myth The Ranger heard. A bit more searching turns up this page about Friendship Estates and another similar recipient of clippings. Sadly it’s still not quite clear what they do with them. And what sort of medical research does Friendship Estates do anyway? It doesn’t sound much like a medical firm. A bit more digging and we discover that Friendship Estates, near Doncaster, are in fact “well known producers and wholesalers of Horse feeds and Pet products”. Huh? Whatever do they want yew clippings for? A search for the keyword ‘yew’ on their site returns nothing. Oh dear. It looks like the EDP was wrong. So the trail goes cold. How frustrating! But hold – what’s this publication (PDF only) on sustainable use of Scottish plants from the Scottish Executive? Seems as though Friendship Estates has a sideline. The Ranger reads this stuff so you don’t have to. Check it out:
Friendship Estates in Yorkshire, is trading and growing medicinal plants for the veterinary market as well as for herbal teas… …Yew clippings (young growth) are collected for the pharmaceutical industry for the production of anti-cancer drugs. Most traded clippings are produced from cultivated hedges rather than wild trees… Friendship Estates in Yorkshire, has been buying clippings from collectors in Scotland (7-8 tonnes in 2000) for supply to Rhone Poulenc. The market is very fickle and demand and price vary considerably: in the past it has been as high as 50p/kg (fresh) but in 2000 it was 30p. The market for clippings has been undermined by synthetic production, and also by the cultivated stands of yew that were established in France and Germany 5 years ago when the market boomed, and which are now beginning to produce.
So, Rhone Poulenc eh? That actually is a pharmaceutical company. Progress. So what do they do with it? Now knowing the company name, Google is very forthcoming:
A semisynthetic form of taxol is the anticancer compound Taxotere… synthesized from the precursor 10-deactylbaccatin III, which is isolated from the needles of the European yew tree Taxus baccata. Because the tree continues growing after the branches providing needles have been harvested, this type of yew tree provides a renewable source of the precursor. Taxotere is not currently marketed in any country, although regulatory approvals by the relevant health authorities have been given. Currently, the leading company in the development of Taxotere as an anti-cancer drug is Rhone-Poulenc Rorer. According to Jean-Louse Fabre, project leader for Taxotere at Rhone-Poulenc Rorer industrial-scale production of Taxotere has begun.
So we reach the end of our internet journey. We know the final destination of the yew clippings and what they are made into. The whole thing is legitimate after all and The Ranger’s urban myth was true. The confusion with the American Taxol is explained: Rhone Poulenc have made a European version of Taxol which is easier to make than the American one, and it needs English yew clippings – not bark. What a complicated journey the Norfolk yew clippings must take before they get to their final destination!