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Theme 13
MEDICINAL PLANTS
Plants have always been of interest to man. The collection and the
use of medicinal plants began many thousands years ago. At an early
period men distinguished and named some kinds of plants they found.
Hippocrates, the father of medicine who described drugs made of
such medicinal plants as hemlock, gentian and many others.
The word drug itself comes from the Dutch word “droog” (via the
French word “drogue”), which means “dried plant”. Some examples
are quinine (from the cinchona [siηkounə]), morphine and codeine
(from the poppy) and digoxin (from the foxglove).
Many of the pharmaceuticals currently available to physicians
have a long history of use as herbal remedies e.g. opium, aspirin,
digitalis (foxglove) and quinine. The World Health Organization
(WHO) estimates that 80 percent of the world’s population presently
uses herbal medicine for some aspect of primary health care.
In addition to the use in the developing world, herbal medicine is
used in industrialized countries by alternative medicine practitioners
such as homeopaths.
All plants produce chemical compounds as part of their normal
metabolic activities. These are divided into primary metabolites, such
as sugars and fats, found in all plants, and secondary metabolites,
compounds not essential for basic function found in a smaller range of
plants, some useful ones found only in a particular genus or species.
Many plants synthesize substances that are useful to the maintenance
of health in humans and animals. These include aromatic substances,
most of which are phenols or their oxygen-substituted derivatives such as
tannins. In many cases, substances such as alkaloids serve as defense
mechanisms against microorganisms, insects. Many herbs and spices
used by humans yield useful medicinal compounds.
The functions of secondary metabolites are varied. For example,
some secondary metabolites are toxins used to deter predation, and
others are pheromones used to attract insects for pollination. Today
many drug plants are cultivated and many are collected from fields
and woods. Some drugs are made from fruits, leaves, flowers, roots
and seeds of the plants.
Here are some medicines made of plants and their use: