Drug Discovery

How are medicines discovered?

Many medicines are first discovered from natural products. These can include molecules made by all kinds of organisms including trees and microorganisms such as fungi. Scroll down to see some examples you might be familiar with.

Active ingredient:

Acetylsalicylic acid

Natural product:

Salicylic acid

Derived from:

Willow tree bark

Salicylic acid

Willow was known as far back at 3000 BC by the Ancient Egyptians and Sumerians as an anti-inflammatory and pain reliever.

In Ancient Greece, Hippocrates used willow bark in tea to reduce fever and pain from childbirth.

The active ingredient, salicylic acid, was isolated for the first time from Willow bark and Meadowsweet flowers, in 1828 in Munich.

1828, a German pharmacist extracted this active ingredient from willow: bitter tasting yellow crystals. He called it 'salicin'.

1853, a French chemist determined the chemical structure of salicylic acid and synthesised acetylsalicylic acid.

1876, clinical trials are conducted on salicylic acid to test it for reduction of fever and joint inflammation.

acetylsalicylic acid

1897, a German chemist working for Bayer finds that adding the acetyl group reduces unwanted side effects.

1899, Bayer names the medicine 'Aspirin'.

1950, Aspirin enters the Guinness World Records for being the most frequently sold painkiller.

Since then, studies have found that acetylsalicylic acid may play a role in reducing the formation of blood clots. Blood clots can cause deadly conditions such as stroke and heart attack if they get stuck and prevent blood from flowing properly.

Now, approximately 10 million Americans take a low dose of aspirin every day.


Click and drag the molecules above to compare their structures.

Acetylsalicylic acid is the same as salicylic acid, except it has an extra acetyl group. It is equally active against reducing pain and inflammation, but has less unwanted side effects than salicylic acid. We can hypothesise that a different part of the molecule is what binds to a protein in the body to have its analgesic effect.

See the website referenced below to learn about the ongoing studies that have been conducted on aspirin.

Active ingredient:

Penicillin

Natural product:

Penicillin

Derived from:

Penicillium notatum mould

Alexander Fleming is recognised as the person who discovered the first antibiotic in 1928. However, the ancient Egyptians were known to treat infected wounds with mouldy bread - this is probably the first known use of penicillin.

Fleming was studying colonies of bacteria on petri dishes when he noticed something unusual on one dish. He noticed that there was a strange colony of mould on one dish, and the area around it was clear from bacteria.

Fleming investigated further, and found that the 'mould juice' was able to kill a wide range of bacteria. His assistants then worked to isolate the penicillin from the mould juice. This pure isolate wasn't very stable or effective, but they published their results in the British Journal of Experimental Pathology in 1929.

In 1939, Howard Florey and his team were working at Oxford University on the purification and chemistry of penicillin. They conducted animal experiments and produced the mould filtrate in large batches.

Over the next ten years, the processes were refined and in 1941, the first human patient was treated successfully with penicillin.

Pharmaceutical companies such as Glaxo (GlaxoSmithKline) and Kemball Bishop (now Pfizer) took over the industrial production of penicillin.

Tu Youyou, © Nobel Media AB. Photo: A. Mahmoud

Active ingredient:

Artemisinin

Natural product:

Artemisinin

Derived from:

Sweet wormwood

Artemisinin was first extracted from its natural product (sweet wormwood, Artemisia annua) by Tu Youyou in 1972. This herb is used in traditional Chinese medicine to treat fever,

Artemisinin is used to treat malaria, a parasitic infection that is spread through the bite of Anopheles sp. mosquitoes and affects over 220 million people globally. It causes severe recurring fevers and can be deadly.

Tu Youyou was awarded the Nobel Prize in medicine for this work in 2015.

Summary Questions

  1. Explain how knowledge of traditional medicines has contributed to drug discovery and design

References