text: The fourth-century Chinese physician Ge Hongs book Zhouhou Beiji Fang () described Artemisia annua extract, called qinghao, as a treatment of malarial fever. Tu Youyou and her team were the first to investigate. In 1971 they found that their extract from the dried leaves (collected from Beijing) did not indicate any antimalarial activity. On careful reading of Ges description they changed their extraction method of using fresh leaves under low temperature. Ge explicitly describes the recipe as: "qinghao, one bunch, take two sheng [2 × 0.2 L] of water for soaking it, wring it out, take the juice, ingest it in its entirety". Following the findings of scientists at the Yunnan Institute of Pharmacology, they found that only the fresh plant specimen collected from Sichuan province would yield the active compound. They made the purified extract into tablets, which showed very low activity. They soon realized that the compound was very insoluble and made it in capsules instead. On 4 October 1971 they successfully treated malaria in experimental mice (infected with Plasmodium berghei) and monkeys (infected with Plasmodium cynomolgi) using the new extract.
  In August 1972 they reported a clinical trial in which 21 malarial patients were cured. In 1973 the Yunnan scientists and those at the Shandong Institute of Pharmacology independently obtained the antimalarial compound in a crystalline form gave the name huanghaosu or huanghuahaosu, eventually renamed qinghaosu (yet later to be popularised as "artemisinin", after the botanical name). The same year Tu synthesized the compound dihydroartemisinin from the extract. This compound was more soluble and potent than the native compound. Other scientists subsequently synthesized other artemisinin derivatives, of which the most important are artemether and artesunate. All clinical trials by this time confirmed that artemisinins are more effective than the conventional antimalarial drugs, such as chloroquine and quinine. A group of scientists in Shanghai, including chemist Wu Yulin, determined artemisinin's chemical structure in 1975 and published it in 1977 when the secrecy rules lifted. The artemisinins became the most potent as well as the safest and most rapidly acting antimalarial drugs, recommended by the World Health Organization for the treatment of different types of malaria.