THE MEDICINAL USE OF TREES

Abigail Turner (OHS)

Trees are thought to have existed on Earth for approximately 370 million years (8% of the Earth’s life), compared to Homo sapiens presence for only the last 200,000 years (0.004% of the Earth’s life). Available documentation suggests trees have been used medicinally for at least 3% of this human existence but may be much longer.

Aspirin is an example of a well-known and frequently used drug derived from the chemical salicin, found in willow bark. It has been used as far back as 3000BC by ancient civilizations such as the Egyptians, in the form of willow bark to reduce inflammation and pain. In the modern era, aspirin was often used as a first-line pain killer for example for ailments such as headaches and toothaches. In the last century its properties as a blood thinner were discovered, taken daily in small doses to reduce the risk of heart attack and stroke. In the last decade evidence for a role of aspirin in preventing bowel cancer has also been found. The yew tree has been revered both in Medicine and mythology for a long time. Although the whole of the yew tree is poisonous, with many deaths being associated with the ingestion of parts of the tree, the yew tree plays a very important role in modern day Medicine. The tree contains taxane alkaloids containing the chemical taxane. It has been discovered that this chemical can help to prevent the formation of new cancer cells, hence taxanes (docetaxel and paclitaxel etc) are used as cytotoxic chemotherapy drugs in the treatment of many types of cancer including breast, gynaecological, lung and prostate cancers. The fact that yew trees can both be used as a poison and a life-saving drug has caused the yew tree to be portrayed as the symbol of immortality as well as an ‘omen of doom’.

The cinchona tree was first used to treat fevers over 400 years ago. However, it was not until 1820 when a compound called quinine was first isolated from the bark of the tree by two French chemists. Now, quinine is widely known and used as an antimalarial drug. An infected mosquito, which acts as a vector, bites the host and malarial parasites enter the host. These parasites live in the body tissues. When ingested, quinine has the ability to kill the malarial parasites, which are living inside red blood cells. However, it may be toxic in high doses and an additional drug is required to kill any malarial parasites which are living inside other body tissues.

Trees already make up a significant number of the 50,000 plant species which are currently used medicinally. However, it is thought that in the Amazon rainforest alone, there might be approximately 4000 undiscovered tree species so that, in the future, thousands of new tree-based medicinal products might emerge. Some may already be being used regularly by indigenous populations.

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Images

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