Quinine. Historically one of the most important
medicines, quinine is a chemical in the bark of Cinchona, a tree native to the
mountains of the Andes. Someone, somewhere, discovered that an extract from the bark of
this tree provided relief from the symptoms of malaria and aided in its cure. Malaria is a
devastating disease caused by a protozoan (a type of microorganism) transmitted by
mosquitoes. This parasite damages the afflicted person’s red blood cells, leading to
fever, chills, possible liver and brain damage, and, in some cases, death. Malaria is
still a serious disease problem in many parts of the world.For several hundred years the powdered bark of Cinchona was
used to treat malaria; in the early 1800s the active ingredient was discovered to be the
alkaloid quinine, and soon factories were extracting quinine from bark.
In the 1930s synthetic forms of quinine became available
but these have not entirely supplanted natural sources of the drug.
Opium. The medicinal use of opium can be traced
back to at least 4000 B.C., and its derivatives are still used today. The source of opium
is the opium poppy, Papaver somniferum. The immature seed capsules of this plant
contain a resin which is dried to make raw opium.
The chemical responsible for the sedating effects of opium
is the alkaloid morphine. Morphine depresses the digestive and respiratory systems, and
relieves pain. It is used medically as a sedative, however individuals who abuse
morphine-based substances soon become used to the drug so that more and more is needed to
produce the desired effects. This often results in both psychological and physical
addiction. Codeine, another derivative of morphine, is also used in medicines to suppress
coughing and relieve pain.
Opium also provides the raw material for making heroin, a
very potent and addictive narcotic. Although codeine and morphine are less intensely
addictive than opium and heroin, they are still highly regulated substances.
Opium is a good example of a substance that is poisonous
in large doses, but whose medical derivatives have curative powers in small,
carefully-regulated doses.
Reserpine. This alkaloid is found in a
shrub of the genus Rauwolfia, which is related to the Madagascar periwinkle. The
common name of this shrub is snakeroot; for years the medical community regarded snakeroot
as a "black magic" cure for snakebite, cholera, and "lunacy." In the
early 1950s the active ingredient, reserpine, was isolated and studied for its medicinal
properties.
Reserpine depresses the central nervous system, and is
prescribed as a tranquilizer for people suffering from schizophrenia. It is also sometimes
used to treat hypertension.
The plant has been used for over 2500 years in India. It
is a good example of a plant whose medicinal properties have only recently became apparent
to the conventional medical community. Only after an Indian scientist studied the remedy,
isolated the active alkaloid, and "proved" its effects did the European and
American doctors and researchers take this "black magic" cure seriously.
Curare. Another example of an alkaloid
used as medicine is curare. Curare is manufactured from an alkaloid extracted from Chondodendron
tomentosum, a vine native to South America. Curare was commonly used by hunters on
their poison arrows; a small amount was sufficient to paralyze many prey animals. Curare
interferes with nerve impulses, resulting in temporary paralysis. In low doses, it is a
useful muscle relaxant during surgery.
Digitalis and digitoxin. These substances are
derived from a familiar garden plant, the foxglove (Digitalis purpurea). Foxgloves
have been used to treat ailments for over 3000 years—though because of toxicity at
high doses, the treatments often did more harm than good. Only when an English physician
investigated the plant’s use in folk remedies and began experimenting on his own were
its true medicinal properties discovered. This work paved the way toward its use in the
treatment of heart disease.
In the case of foxgloves, the active ingredients are not
alkaloids—but rather the cardiac glycosides, digitalis and digitoxin. These
substances are useful in the treatment of congestive heart failure. By slowing and
strengthening the heartbeat, they improve circulation and facilitate the removal of
accumulated fluids from the patient’s tissues.
