Willow Bark to Wonder Drug

The story of the discovery of aspirin stretches back more than 3500 years to when bark from the willow tree was used as a pain reliever and antipyretic. It involves an Oxfordshire clergyman, scientists at a German dye manufacturer, a Nobel Prize-winning discovery and a series of pivotal clinical trials. Aspirin is now the most commonly used drug in the world. Its role in preventing cardiovascular and cerebrovascular disease has been revolutionary and one of the biggest pharmaceutical success stories of the last century.

Evidence for this early use of willow as an analgesic and antipyretic first surfaced in 1862. Edwin Smith (1822–1906), an American trader living in Cairo purchased a pair of ancient documents, the provenance of which was unknown. These scrolls dated back to around 1500 BC and are amongst the most important historical documents in medicine. One of these is now known as the Edwin Smith Surgical Papyrus and details 48 surgical cases and their management. The other is now known as the Ebers Papyrus. This was an Egyptian record of around 160 herbal and vegetable remedies. One of these is the first written record of the use of tjeret or salix (now known as willow) for treatment of non-specific pains. This herbal knowledge was passed on as empires rose and fell. The use of willow bark for pain relief continued through ancient Greece, where it was recommended by Hippocrates to relieve the pain of childbirth, through to Roman times, when its use was recorded by Pliny the Elder.

Many traditional therapies were used for pain relief over the following centuries but were not studied systematically. The study of natural remedies received a boost with the discovery that the bark of the cinchona tree had fever-relieving properties. This bark was imported at great expense from South America. Although it was unclear at the time, we now know that cinchona is a source of quinine, the first treatment for malaria. It was with this background that in 1763 the Reverend Edward Stone, an Oxfordshire clergyman and fellow of Wadham College at the University of Oxford, investigated the use of willow bark. His letter to the president of the Royal Society outlining his findings survives today. He described using willow bark as a treatment for aguish (fever and shivering): ‘There is a bark of an Englifh tree that, which I have found by experience to be a powerful aftringent, and very efficacious in curing aguifh and intermitting diforders’. Reverend Stone left the willow bark to dry on the outside of a baker's oven for 3 months then pounded and sifted it into a powder. He reported: ‘It hath been given I believe to fifty perfons, and never failed in the cure, except in a few autumual and quartun agues, with which the patients have been long and feverely afflicted’. This letter is likely to be the driving force behind the use of willow bark to treat fevers by many physicians of the time.

The active ingredient in willow bark was not discovered until 1828 when Johann Buchner first refined willow bark into yellow crystals and named it Salicin (after Salix, the genus of the willow tree). In 1829 the process was further refined by Pierre-Joseph Leroux in France and taken a step further in 1838 when Raffaele Piria produced a stronger compound from the crystals isolated from willow bark, which he named salicylic acid.

Since then chemists have given us paracetamol, ibuprofen and clopidogrel. Asprin has been scientifically proven to prevent the development of platelets that can cause Alzheimers. It is truly a wonder drug and because of this we must reconsider our exploitation of rainforest. As many tree species become endangered or indeed extinct, how many scientific discoveries will be lost to us. Saving trees may not only save the lives of many endangered animal species but may hold the answer to finding a cure for cancer or other devastating diseases.

Ode to a Tree 

I bathe in your shadow,

striped by filtered light,

the gentle breeze bending as it curves around us.

A strange couple,

me,  just seven and a half,

 you more than a century.

What knowledge

passes from one to the other?

A child and tree.

Thanks for reading. Adele