Plants have been used by humans for their medicinal values for thousands of years. Scientists have discovered plant-derived alkaloids beneficial for the use of general and local anesthetics. Abused as drugs by the public, such anesthetics have great importance in the field of medicine to suppress brain activity, nerve transmission and muscle function for pain control. Although possession of some of these plants is illegal in many countries, their importance for use during surgery has been proven.
Curare is a chemical compound that comes from the sap produced by many rainforest vines, such as the Pareira vine. Extracted by South American natives, it was used as a poison to apply to the tips of arrows and darts causing asphyxiation in prey or victims. The anesthetics produced by curare are curarine and tubocurarine, which relax muscles during surgery by preventing transmission between nerve endings. The down side of using this type of anesthetic is sometimes the patient is awake during the procedure. This natural anesthetic is still used today. However it is given intravenously, resulting in less quantity of anesthetics delivered.
Prized for the euphoric sensations it produces, opium comes from the seed pods of the poppy plant Papaver somniferum originating from parts of Asia and the Mideast. Opium was first used as a medicine in the fifth century B.C. and has gained a significant role in pharmaceuticals. Although highly addictive, many natural painkillers such as codeine, morphine and papaverine have been derived from the opium poppy. Morphine is known as the most effective painkiller in the world because it acts on sensory nerves in the brain, blocking the pain signal to other parts of the body. Heroin is a refined product of morphine; however, because of its potency, it is forbidden for medicinal use.
Coming from the coca shrub Erythroxylum sp., cocaine has an extensive history of being known as a stimulant. Before the Spanish Conquistadors, the coca plant was highly prized by rulers of the Peruvian area. The natives of the region would chew on the leaves to be able to walk long distances without food or water. It was not until the late 1800s that cocaine was used for its anesthetic properties and became popular in the world of pharmaceuticals. Because the natural anesthetic property of cocaine paralyses nerve endings responsible for the feeling of pain, it became valuable during surgery and dental procedures. Today, Novocain is a popular medicine that contains cocaine's anesthetic values, but lacks it stimulatory effects.