About Pharmacognosy


Pharmacognosy Lecture Midterm 4th Semester < Click here

WHAT IS PI-IARMACOG NOSY?
Pharmacognosy, which literally means a
knowledge of drugs or pharmaceuticals,

has been a part of the healing arts and sci-
ences since mankind first began to treat

llncsscs. It has developed from ancient
civilizations that used parts of plants and

animals to concoct various potions to elim-
inate pain, control suffering, and counter-
act disease. Pharmacognosy has risen from

the mysterious incantations of voodoo

tribes and has survived the unwritten se-
cret recipes of medicine men. It has pro-
gressed from an era of empiricism to the

present age of specific therapeutic agents.

Today, pharmacognosy is a highly spe-
cialized science that represents one of the

major disciplines of pharmaceutic educa-
tion. A number of the drugs used by the

ancients are still employed in much the

same manner by today’s medical practi-
tioners. Although it is true that extraction,

separation, isolation, and identification of
the component constituents of plant and
animal drugs have occurred in relatively
recent years, nevertheless the purpose for
which many of these medicinal substances
are employed today parallels closely the
use for which they were intended by our
predecessors in the study of pharmacy and
medicine.
Because of the interest it engenders in

many of the scientists of today, pharn-ia-
cognosy is a respected discipline that has

no counterpart in the other professions.

Perhaps because the lay public has heard
little about the term pharmacognosy, there
is a lack of recognition and, further, a lack
of association of the term with the specific
subject matter it represents. However, an
intuitive curiosity is inherent in the average

person who reads or hears of opium, mor-
phine, foxglove, insulin, reserpine, thy-
roid, penicillin, blood plasma, polio vac-
cine, and even the much maligned castor

oil!
During the past few years, as a result of

the intense concern with all aspects of ecol-
ogy, there has been a renewed interest in

so-called “natural” foods and drugs. The
availability of an extremely wide variety of
these products, ranging from fenugreek

tea to ginseng chewing gum, has stimu-
lated the public to learn more about them.

Consequently, a vast literature on natural
drugs written by laymen and intended to

inform other laymen has come into exis-
tence. Much of this literature is relatively

inaccurate, consisting of beliefs and opin-
ions substituted for facts. The pharmacist

must, of course, be aware of the existence
of such pseudopharmacognostic writings,
primarily to be able to caution his patients
concerning them and to correct any factual
misinformation gained from reading them.
Chapter 16 in this text provides accurate,
up-to-date information on these so-called
“health foods” and herbs.
In order to gain proper perspective about
a science that deals with plant and animal

drugs and their constituents, it is exceed-
ingly helpful to survey past records and to

recognize those who have contributed to
the subject matter that constituted the field
of pharmacognosy in its beginning. By trial

and error, primitive man must have ac-
quired biologic knowledge that was useful

in determining which plants and animals
possessed food value and which were to
be avoided because they were unpalatable,
poisonous, or dangerous. His observations
were handed down from one generation to
another and were added to by his progeny.
The healing powers of certain herbs, roots,
and juices were undoubtedl y discovered
by accident; but once these attributes were

learned, they were too important to he for-
gotten. The Babylonians made clay models

of the human body, and earl y writings in-
dicate that they were aware of the medic-
inal effects of a number of plants. It is a

well-known fact that the ancient Egyptians
were adept at embalming the dead and that
they possessed an understanding of the
human anatomy as ‘.,. , ell as a knowledge of

the medicinal uses of many plants and an-
imals, according to the Papyrus Eku’s. This

famous document, written in 1550 nc., was
found in the tomb of a mummy and is now
preserved at the University of Leipzig.
Dioscorides, a Greek physician who
lived in the first century AD., wrote his “Do
Materia Medjea” in 78 A.D. in which he
described about 600 plants that were
known to have medicinal properties. Of
these, a surprisingly large number are still

important in modern medicine. Aloe, bel-
ladonna, colchicum, ergot, hvoscamus,

and opium are a few that were used then
in much the same manner as they are used
today. Galen (131-2111) An.) was a Greek
pharmacist-physician who lived in Rome

and who described the method ot prepar-
ing formulas containing plant and animal

drugs. He devoted considerable time to

compiling this knowledge, which was dis-
tributed throughout 20 hooks. As a tribute

to his accurac y in recording his observa

tions, the term “galenical” pharmac y was

originated.
From this humble beginning, medicine
and pharmacy gradually emerged along
separate paths: the physician diagnosed
the ailment and prescribed the remedy,

and the apothecary or pharmacist special-
ized in the collection, preparation, and

compounding of the substance. Thus, the
term materia medica, meaning medicinal

materials, was synonymous with the sub-
stances and products derived from natural

sources and was employed by the physi-
cians of that era.

The term pharmacognosy was intro-
duced by C. A. Seydler, a medical student

in Halle/Saale, Germany, in 1815. This
name is formed from two Greek words,
p/zai’nuiknu, drug, and gnosis, knowledge.
The most comprehensive idea of the scope
of pharmacognosy was presented by
[: luckiger who stated that pharmacognosy
“is the simultaneous application of various

scientific disciplines with the object of ac-
quiring knowledge of drugs from every

point of view.”
Pharmacognosy ma y he defined as “an
applied science that deals with the biologic,

biochemical, and economic features of nat-
ural drugs and their constituents.” It is a

study of drugs that originate in the plant
and animal kingdoms. Modern aspects of
the science include not only the crude
drugs but also their natural derivatives.

Digitalis leaf and its isolated glycoside, dig-
itoxin; rauwolfia root and its purified al-
kaloid, reserpine; and thyroid gland with

its extracted hormone, th yroxine… are all

part of the subject matter of pharrnacog-
nosy’

In some instances drug constituents
have been partially replaced in commerce

by synthetic compounds of identical chem-
ical structure and therapeutic properties;

such natural and synthetic substances
often can he distinguished by physical and

chemical tests. For example, natural cam-
phor is obtained from the camphor tree by

steam distillation; it is dextrorotatory in its

reaction to polarized light. In contrast, syn-
thetic camphor may be manufactured by

either of two methods: by total synthesis
from vinyl chloride and cyclopentadiene (a

completely synthetic process) or by semi-
synthesis from pinene derived from pine

stumps (not entirely a synthetic process
but a chemical modification of a natural
product). Synthetic camphor is racemic
and can he differentiated easily from the
natural form.

Epinephrine, caffeine, codeine, ephed-
rine, menthol, penicillin, and other chem-
icals may also be obtained from either the

natural source or by partial or total syn-
thesis. They are considered a definite part

of pharmacognosy.

In a broad sense, pharmacognosy em-
braces a knowledge of the history , distri-
bution, cultivation, collection, selection,

preparation, commerce, identification,
evaluation, preservation, and use of drugs
and economic substances that affect the
health of humans and other animals. Such
economic substances extend beyond the

category of crude drugs and their deriva-
tives to include a variety of commercial and

medicinal products often requiring com-
plicated methods of preparation: allergens,

allergenic extracts, antibiotics, immunizing

biologics, flavoring agents, and condi-
ments. In a restricted sense, the definition

of pharmacognosy implies a particular
knowledge of methods of identification
and evaluation of drugs.

As a part of the pharmaceutic curricu-
lum, pharmacogiiosy forms an important

link between pharmacology and medicinal

chemistry on one hand and between phar-
maceutics and clinical pharmacy on the

other.
Pharmacology, like pharmacognosy, is

an outgrowth of materia medica, the an-
cient science that dealt with all aspects of

medicinal agents. Now, in this more spe-
cialized era, pharmacognosy deals primar-
ily with information on the sources and

Constituents of natural drugs, and phar

macology is concerned with their actions

and effects.

Methods of procurement and prepara-
tion affect the price of drugs; thus, insofar

as economics are concerned, pharmacog-
nosy is intimately associated with the

phases of pharmacy administration that

deal with prescription pricing. The rela-
tionship of pharmacognosy to dispensing

pharmacy and clinical pharmacy is obvious

when one considers the number of natu-
rally derived drugs that are handled by the

pharmacist in this age of drug specialties.

Because of his knowledge of drug constit-
uents, the pharmacist is able to predict not

only the chemical and physical incompat-
ibilities encountered in compounding but

also the therapeutic i n compatibilities that
the patient may encounter when utilizing
P, drug concomitantl y with other prescribed
or self-selected medications.
When supplying both prescription and

over-the-counter (OTC) medication to pa-
tients, the pharmacist also provides infor-
mation required for the safe and effective

use of such drugs. The pharmacist further

serves as an information source of all as-
pects of drugs to his colleagues in the med-
ical, dental, and nursing professions.

These advisory roles are made possible by
the vast background of the pharmacist, the

drug expert, in fields such as pharmacog-
nosy, pharmacology, medicinal chemistry,

and pharmaceutics.

Any treatise on plant and animal prod-
ucts encompasses a wide variety of uses

inasmuch as natural substances are em-
ployed in almost every known industry.

Although the pharmacist is mainly con-
cerned with those substances having ap-
plication to public health, he realizes that

many of these therapeutic aids are also uti-
lized as beverages, as spices and condi-
ments, in confectioneries, and as technical

products.
Coffee beans and tea leaves both yield
caffeine which has medicinal application;
yet the original sources are mainstays in
the diet of the American public.