In Ge Hong's A Handbook of Prescriptions for Emergencies (肘后备急方), I noticed one sentence "A handful of Qinghao immersed in two liters of water, wring out the juice and drink it all" (青蒿一握, 以水二升渍, 绞取汁, 尽服之) when Qinghao was mentioned for alleviating malaria fevers. Most herbs were typically boiled in water and made into a decoction before taken by the patients. This unique way of using Qinghao gave me the idea that heating during extraction might have destroyed the active components and the high temperature might need to be avoided in order to preserve the herb's activity.
Recorded Laureate-written autobiography for Les Prix Nobel, Nobel Prize Outreach, 1 December 2015 source