Himalayan Yew a Vietnam cancer cure in the making

(No.7, Vol.3, Aug 2013 Vietnam Heritage Magazine)

The rare and valuable Himalayan Yew is endemic to Lam Dong Province in the Central Highlands. It ranks among the species that contain the active agent 10-DB III, which is converted into taxol to make the foremost cancer treatment medicine in the world.
In 1994, when a cancer treatment medication that was produced by the United States from Himalayan Yew appeared on the market, Vietnamese scientists clamored, since, 61 years prior to that, in the book Gazetteer of Indochinese Plants, the foreign researcher H. Lecomte had announced the discovery of a population of Himalayan yew consisting of 10 individual trees in the pristine forest of Cam Ly in Dalat.

An old Himalayan Yew in a
forest in Lam Dong Province
Photos: Nguyen Hang Tinh

Also in that year, Professor Le Thi Xuan of the Biotechnology Institute, along with a number of scientists working in Dalat City, sought out Cam Ly.
‘The entire survey team fell silent when they discovered that the forest described by H. Lemonte as having a population of Himalayan yew had already been utterly felled to plant coffee,’ Associate Professor Duong Tan Nhut, Deputy Director of the Central Highlands Institute of Biology, recollected.
The scientists took a specimen of Himalayan yew to look for the village of the K’Ho people— the group of inhabitants who had long since lived in Cam Ly— in order to inquire about the species.
In June of 1994, they discovered a population of about 25 trees on the tottering mountainside at an elevation of over 1,500 meters, towards the east of the Lam Vien Plateau.
They collected several leaf, branch, flower and fruit specimens and then sent them to the United States for assessment.
The response exceeded all expectations; Not only was it the rare and precious Himalayan yew (scientific name Taxus Wallichiana Zuccarini), but it was also a species endemic to Vietnam with a 10-DB III content ten times higher than the American yew and a hundred times higher than the Mexican yew.
For the next 15 years, many universities, forestry agencies, and researchers dispatched survey teams to scale mountain passes and wade through streams to enter the depths of the forests in pursuit of the Himalayan Yew, but they found no more than ten populations, each of which had just a few scattered trees or several tens of trees, and most of which still had only a hundred or so trees.
Almost all the populations were situated on precarious mountainsides adjacent to rivulets at an altitude of 1,500 meters in forested land that was constantly damp, mushy, rich in hummus, carpeted in thick decaying matter, and beneath the umbrage of a canopy of broad-leafed trees.
Mr Vo Danh Tuyen of the Deputy Branch of the Lam Dong Department of Forest Management related that the distribution range of the Himalayan yew is limited, since the trees are only found in Lam Dong.
This species of tree grows slowly. After growing for hundreds of years, it still only has a diameter of just a few dozen centimeters. The tree’s frequency of proximate cross-fertilization has led to the degeneration of the population’s genetics. Another consideration is that the Himalayan yew often interspersed within a wide leafed, verdant forest, so that it has a low regenerative ability. Most mature Himalayan yews are encroached upon by other trees or creeper vines that cling to the tree trunks, causing them to be of poor quality. They also attract pestilent insects and become hollowed out. This situation threatens the Himalayan yew with extinction and the tree has already been added to Vietnam’s red list for conservation.

Himalayan Yew fruits.

Reproduction of Himalayan Yew at Vimedimex.

Nevertheless, the Himalayan yew is still insistently hunted by tree thieves in order to sell it to lumber smuggling magnates, since the trees’ trunks are very solid, the wood is a mild golden color, and the dark brown heartwood is quite beautiful and of high economic value.
In other respects, many places abound with rumors that owning a work of art carved from Himalayan yew wood is spiritually efficacious— that it blesses the family, extricates relatives from ill fortune, and allows them to thrive, succeed and achieve eminence.
Most perturbing was the case in which tens of Himalayan yew trees hundreds of years old on Voi (Elephant) Mountain in Duc Trong District were hacked to pieces in 2008.
Down from over a hundred trees, now only about 40 trees remain there due to constant felling.

Processing Himalayan Yew at Vimedimex.
Photos: Kim Anh

Certain people venture into the depths of the forest in search of Himalayan yew because of hearsay that the roots or bark of the trees, when brewed into a medication in the manner of traditional Chinese medicine, yields a cure for cancer.
‘At present, there are no specific measures for the protection of the Himalayan yew and there are only general agreements to manage their protection, just like any other species of forest trees, while the Himalayan yew is a rare and valuable tree species that requires special protective regulations,’ said a leader of the Lam Dong Office of Agriculture and Rural Development.

Scientists estimate that if a cancer medication were to be extracted and prepared from Himalayan yew bark, it would take three to four decade old trees. With the small number of trees found in Lam Dong, there are only enough to produce a few dozen doses.
A research team from the Central Highlands Institute of Biology, under the supervision of Associate Professor Duong Tan Nhut, PhD, has conducted breeding research on thousands of trees and has successfully experimented on cultivating Himalayan yew in Lam Dong through provining methods in 1994.
The Lam Dong Centre of Forest Biological Research has also succeeded in breeding the trees, researched the ecological conditions for tree development, and planted three hectares of Himalayan yew.
The Dalat Centre for Research on the Cultivation and Processing of Medicinal Plants, under the pharmaceutical stock company Vimedimex, currently owns two Himalayan yew plantations with a total area of seven hectares.
In 2000, the Central Highlands Institute of Biology completed a project to extract the active agent 10-DB III.
Vimedimex expects to build a factory to produce cancer medicine from Lam Dong Himalayan yew with an investment expenditure of 100 billion Vietnamese dongs.
They hope that a cancer-fighting medication from Himalayan yew with a Vietnamese brand name will enter market circulation in 2013.

By Kim Anh
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