[♪ INTRO]
Malaria has been haunting humans for as long as we’ve existed.
And for a long time, there was no widely-known cure that worked on all strains of it.
But in the 1970s, the scientist Tu Youyou identified an ancient Chinese remedy
that eventually became one of the main modern defenses against this disease.
And thanks to her, it’s now saved countless lives over the last 50 years.
Tu was born in the Chinese city of Ningbo in 1930,
and originally didn’t plan to dedicate her life to medicine.
But at 16, she got sick with tuberculosis and had to leave school for two years.
And after she recovered, she became determined
to find cures for illnesses like the one she’d experienced.
So, she studied pharmaceutics at Beijing Medical College
and later went on to study at the Academy of Traditional Chinese Medicine.
Then, Tu started her career as a researcher. She studied herbs used in
traditional Chinese medicine as a way of treating parasitic infections.
And that soon made her the perfect person for a very important job.
In 1967, during the Vietnam War,
North Vietnam reached out to China for medical help.
At the time, malaria was spreading among its troops,
and they were dying in large numbers.
To make matters worse, the parasite that causes malaria
had become resistant to the main treatment they were using, called chloroquine.
So China put together an initiative called Project 523
to find a cure for this deadly strain of malaria.
And in 1969, Tu became the head of it.
She and her research team started out by traveling to Hainan Island
in southern China, where there was a malaria outbreak.
There, they could see the effects of the illness firsthand
and research effective treatments in the field.
Then, once they had a better understanding of the disease, Tu and her team
returned to Beijing and started looking for remedies in ancient Chinese medical texts.
Since malaria has been around for so long, it was a frequent topic in these writings.
And the team had over two millennia’s worth of work to study…
so they got down to business.
They tested 240 thousand compounds on mice that had been infected with malaria.
And… nothing worked.
But then, while looking back over her notes, Tu found an interesting reference
to the herb qinghao, also known as sweet wormwood.
She had tested qinghao before and found that it had some effect,
but it wasn’t reliable enough to make this herb a serious choice for treatment.
The reference made her dig a little deeper, though.
And while reading a text from around 400 C.E., Tu realized that the authors weren’t
boiling the leaves to collect the extract, as she’d done.
Instead, they were immersing the leaves in water and wringing out the juice.
Basically, they were making an extract of qinghao without heating it at all.
So Tu tried following those instructions:
She made what’s called an ether solution,
where the leaves are steeped in a mixture of water and alcohol.
This extracted the active compounds in the herbs —
without breaking them down, as boiling can do.
And this time, when she tested the compound on mice and monkeys,
it cured malaria 100% of the time.
They still hadn’t tried it out on humans, though, so as a final step,
Tu and her colleagues tested the medicine for side-effects on themselves.
Then, they delivered it to 21 patients on Hainan Island.
And, incredibly, every single one of them recovered.
As it turned out, the key to this life-saving cure
was an active compound from the wormwood plant called artemisinin.
And it’s effective against malaria because of the way it interacts
with the parasites that cause the disease.
Once they mature, these parasites contain a compound called hemozoin —
something they ultimately get from digesting human blood.
And when artemisinin encounters hemozoin,
the two compounds react to create unstable atoms known as free radicals.
Those atoms have uneven numbers of electrons,
unlike most atoms and molecules, which have electrons in pairs.
As a result, free radicals react extremely readily with other atoms —
to the point where they can actually tear cells apart.
And these violent reactions destroy the parasites.
Which is kind of satisfying:
feeding on human blood is ultimately the thing that kills them.
Now, artemisinin can be toxic to human cells, too, for the same reason.
It can react with compounds in our bodies and create those free radicals.
But luckily, artemisinin reacts more readily with hemozoin,
than it does with the iron in our cells.
It takes a pretty high dose to damage human cells,
so by controlling the dose, it’s possible to make sure only the parasite dies.
Today, artemisinin is still distilled from the dried leaves or flower clusters
of the sweet wormwood plant and used to treat malaria.
In fact, two decades after Tu’s discovery, the World Health Organization
recommended that artemisinin be used in combination with other drugs
as the first line of defense against malaria.
And in 2015, Tu received the Nobel Prize in Physiology or Medicine,
along with the American parasitologist William Campbell
and Japanese microbiologist Satoshi Ōmura.
But in spite of all the honors she’s received, Tu has said
that her biggest accomplishment is doing something to help the world — and there is
no doubt that millions of people have survived or lived healthier lives thanks to her.
If you enjoyed this, you might like some of our other Great Minds videos,
which like the name says, celebrate some of the greatest minds in science.
If you want a place to start, I would like to recommend our episode about Alice Ball,
a woman who changed leprosy treatment in her twenties!
[♪ OUTRO]