People have been using plants to cure a great number of illnesses for thousands of years.
In fact, one of the earliest pieces of documented evidence is the Ebers papyrus (named after the German egyptologist who translated it) listing hundreds of plants, which has been dated at around 1500 BC. Much later, in the ninth century, the French king Charlemagne instructed monasteries and abbeys to grow medicinal plants to be used for treating patients.
Plants were originally used in their natural form, as a whole or in parts (roots, leaves), and taken as herbal teas or decoctions. Their virtues – and indeed their dangers – were established gradually, as more plants were used and their effects were observed.
Knowledge of their active ingredients and therapeutic properties accelerated in the 19th century. Advances in the field of chemistry led to certain compounds being isolated and identified: this was the case with morphine, which is obtained from opium poppies and is now a gold standard pain relief drug made from chemical synthesis, or codeine, another molecule obtained from poppies, which is used to relieve pain and coughs.
Progressively, new plant molecules were identified and tested by pharmacologists and researchers on in vitro and in vivo models to evaluate their pharmacological behaviour.
Although foxglove is toxic for the heart if consumed whole, its active ingredient digoxin can be isolated and is prescribed at low doses as a cardiotonic agent. Meadowsweet and willow bark are used to extract a salicylate derivative which is the original version of today’s aspirin. Madagascar periwinkle contains the alkaloids vinblastine and vincristine which are commonly used in cancer drugs.
In fact, the list of examples of how the plant kingdom can treat illnesses is endless: colchicine, used to treat gout, comes from colchicum; the malaria drug quinine from cinchona; the parasympathomimetic drug atropine from belladonna; and the cancer drug paclitaxel is isolated from the yew tree.