This article records tradition as it has been passed down and reported. Its sources are not yet part of the atlas's verified catalogue.
For years, teams screening Artemisia annua, sweet wormwood, for antimalarial activity got inconsistent results. Sometimes the plant extract worked in animal tests. Sometimes, from the same species, it did not. The standard chemistry of the day pointed to heat: boil the plant material in water or alcohol, the way herbal remedies and most extraction chemistry of the period both did, to pull the active compounds out efficiently. Tu Youyou, trained as a pharmaceutical chemist rather than a botanist, looked at the failures and asked a chemist's question instead of a botanist's: what if the compound simply could not survive being boiled? A passage in a 1,600 year old text, Ge Hong's Emergency Prescriptions Kept Up One's Sleeve, described soaking qinghao in water and drinking the juice raw, not decocting it. Tu treated that as a chemistry clue rather than a historical curiosity. In 1971 her team switched to a solvent that would pull the compound out at low temperature: diethyl ether, with a boiling point of about 35 degrees Celsius, well under the threshold she suspected was destroying the activity. On 4 October 1971, an ether-extracted sample, catalogued as sample 191, achieved complete suppression of the malaria parasite in animal testing. Nothing about the plant had changed. The chemistry had. By 1972 the team had isolated the pure active compound, artemisinin, from that same low-temperature extract. The discovery is usually told as a story about an ancient text pointing the way to a modern drug, which it is. It is also, underneath that, a story about correctly diagnosing that a well-established extraction method was quietly cooking the answer out of every sample before anyone got to test it.