1,892: The number of herbs mentioned Compendium of Materia Medica. Credit: Lou-Foto/Alamy Stock PhotoIn the case of a plant molecule, colchicine, Mitchison’s long-time study subject, its short half-life corresponds to local action in the liver. “These special features of plant-derived molecules cannot be achieved using standard synthetic drugs, which are systemically adsorbed,” he says. “I would encourage medical researchers to have an open mind regarding different medical traditions.”In Tu’s lecture after winning the Nobel Prize in Physiology or Medicine, she recalled the difficulties of plant research, ranging from managing extraction and purification technologies, to the variables involved in the study of the six Artemisia species, such as accounting for origin, harvest season, and the use of different plant parts.