Tu Youyou won the nobel prize in medicine for a recipe she found and worked on from nearly 1500 years ago. From Wikipedia: its preparation was described in a 1

Tu Youyou won the nobel prize in medicine for a recipe she found and worked on from nearly 1500 years ago. From Wikipedia: its preparation was described in a 1,600-year-old text, in a recipe titled, "Emergency Prescriptions Kept Up One's Sleeve". At first, it was ineffective because they extracted it with traditional boiling water. Tu Youyou discovered that a low-temperature extraction process could be used to isolate an effective antimalarial substance from the plant; Tu says she was influenced by a traditional Chinese herbal medicine source, The Handbook of Prescriptions for Emergency Treatments, written in 340 by Ge Hong, which states that this herb should be steeped in cold water. This book contained the direction to immerse a handful of qinghao in the equivalent of two litres of water, wring out the juice and drink it all. After rereading the recipe, Tu realised the hot water had already damaged the active ingredient in the plant; therefore she proposed a method using low-temperature ether to extract the effective compound instead. The animal tests showed it was completely effective in mice and monkeys.