Artemisinin
Artemisinin discovery
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.
artemisinin development and refinement
As we saw on the previous page, Artemisinin is a natural product derived from sweet wormwood that is used to treat malaria. Artemisinin kills malaria parasites quickly, and is able to kills them in all of their lifecycles.
However, has poor pharmacokinetics (absorption, bioavailability, distribution, metabolism, excretion), in particular low bioavailability, meaning it doesn't absorb well into the body and only a small proportion of the medicine becomes available to kill the parasite. It is also really costly to produce.
Below you can look at some of the analogues (molecules with similar structure) of artemisinin. Look at the skeletal structure of these medicines.
What do you think the most important part of the molecule is for killing malaria parasites? The part of the chemical structure that is responsible for the medical activity is called the pharmacophore.
What do you think the effect of changing the side chains is?
Which of these three molecules are better treatment options? Why?
Which ones would you put on the Essential Medicines list?
Artemisinin
Isolated from sweet wormwood
Effective against malaria parasites
Low pharmacokinetics
Low bioavailability
Resistance developed
Artemether
Chemically altered in laboratory
Fat soluble
Higher bioavailability
Artesunate
Chemically altered in laboratory
Water soluble
Higher bioavailability
Resistance
Resistance is the term used for when medicines are no longer effective against certain pathogens, usually because the pathogen has developed a defence mechanism against the medicine.
Resistance is an example of natural selection and evolution.
As a result, scientists need to keep working on new versions of medicines.
Often, anti-parasitic, antibiotics and anti-viral medications are taken in combination where one tablet has two active ingredients. This gives the medicine a better chance at killing the pathogen quickly and less change for the pathogen to develop resistance.
This is why the medicine combination : artemether + lumefantrine is on the Essential Medicines list.