Contrary to popular belief, aspirin does not occur in nature, it is not found in the willow tree. But there is a connection. Aspirin, or acetyl salicylic acid, was first produced commercially by the Bayer Company based on a synthesis by Felix Hoffmann, a chemist working in 1897 for the Bayer company in Germany. While Hoffmann did indeed synthesize the first commercial sample of acetylsalicylic acid, he certainly was not the first to produce the substance in the laboratory. That honor goes to Karl Friedrich Gerhardt, who in 1853 at Montpelier University in France made an impure version with an aim towards improving on the effects of a salicylic acid, a commonly used pain killer. At the time salicylic acid was extracted from the leaves of the meadowsweet plant and was used for the treatment of fevers and pain, particularly of the arthritic variety. But it had to be taken in large amounts, had a bitter taste and often caused stomach irritation. Gerhardt identified the molecular structure of salicylic acid and thought he could modify it and produce a better product. He abandoned the project when he could not produce the 鈥渁cetylated鈥� version reliably.
How did salicylic acid come to be used as a pain reliever in the first place? That鈥檚 a long and engaging tale. It all starts with a recommendation in the famous, 3500-year-old Egyptian Ebers Papyrus about treating an inflamed wound with a concoction made from the leaves of the white willow tree. This makes sense in view of the fact that willow leaves and bark contain a substance known as salicin, which in the body can be converted to salicylic acid. Of course, not all of the prescriptions for inflammation in the Ebers papyrus turned out to be as compelling scientifically. A poultice made from chopped bat or a potion of wasp鈥檚 dung in fresh milk have not stood the test of time. But salicylate containing plants have. Hippocrates championed the use of willow bark for the pain of childbirth and the Roman physician Celsius described the treatment of inflammation, characterized by redness, heat, pain and swelling, with willow leaves. The ancient Chinese, as well as North American Indians knew about the special properties of plants like the meadowsweet.
The true scientific era of the salicylates began in 1763 when the Reverend Edward Stone presented a report to the Royal Society in England about the use of willow bark in the treatment of fever. Stone was a believer in the rather curious Doctrine of Signatures which maintained that cures could be found in the same locations that spawned diseases. Since fevers were often associated with swamps, probably because of mosquito-borne infectious agents, it was here that Stone looked for cures. He tasted a sprig of willow and was stunned by its bitterness. This was exciting stuff though, because he knew that quinine, an equally bitter substance, was useful for the treatment of malarial fever. So he decided to give willow bark a try. Stone dried and powdered the substance and tried it on fifty patients with rheumatic symptoms. The bark worked!
The search was now on to discover the active ingredient. By 1828, salicin, named after Salix alba vulgaris, the botanical name of the willow, was isolated and was shown to have a medicinal effect. Furthermore, it could be converted in the laboratory to salicylic acid, which was even more potent as a drug. It was around this time that Gerhardt became interested in solving the problem of bitterness and gastric complications, a problem that was eventually solved by Felix Hoffmann some fifty years later. Hoffmann鈥檚 father had long been taking salicylic acid for arthritis, but he could no longer take it without vomiting. The chemist searched the literature for alternate forms of salicylates and came upon Gerhardt鈥檚 work. By this time chemical techniques had been refined to the extent that he was able to make acetylsalicylic acid in a pure form and the aspirin era was under way. The name was chosen by combining 鈥渟piric acid,鈥� as salicylic acid was originally known, with 鈥渁鈥� for 鈥渁cetyl.鈥� The rest, as they say, is history.
It should be obvious from the preceding that aspirin itself does not occur in nature, but similar, less effective substances do. Willow extracts sold in health food stores cannot compare with the demonstrated effectiveness of aspirin; in fact aspirin came about as an improvement on the natural salicylates. Furthermore, aspirin鈥檚 anticoagulant effect can be attributed to the acetyl part of the molecule which is responsible for inactivating an enzyme that leads to blood clot formation. So there is really no point in chewing on willow bark to prevent a heart attack. But carrying around a 325 mg tablet of aspirin and chewing it if a heart attack is suspected is a good idea.
