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Transcript Pharmacognosy-I

Dr. Wafaa M.A. AlShakh Hamed
• Reference text:
• Trease and Evans Pharmacognosy; (Latest
• Robbers JE, Speedie MK, Tyler VE (Eds.);
Pharmacognosy and
Pharmacobiotechnology; latest edition.
General Introduction
• Pharmacognosy is the study of those natural
substances, principally plants that find use in
• Pharmacognosy: derived from the Greek, pharmakon
a drug and gnosis in knowledge .
• Pharmacognosy: may be defined as a science that
deals with the biological, biochemical, and economic
feature of natural drugs and their constituents. It is
study of drugs that originate in the plant and animal
Introduction to Pharmacognosy
A brief history of natural products in medicine
Value of natural drug products
Production of natural drug products
The role of natural products in drug discovery
General principles of botany: morphology and
I. The history of natural products in
• A great proportion of the natural products used as drugs
• The study of drugs used by traditional healers is an
important object of pharmacognostical research
• Sumerians and Akkadians (3rd millennium BC)
The 18th century, Pharmacognosy
• Linnaeus (naming and classifying plants)
• At the end of the 18th century, crude drugs were still
being used as powders, simple extracts, or tinctures
The era of pure compounds
(In 1803, a new era in the history of medicine)
• Isolation of morphine from opium
• Strychnine (1817)
• Quinine and caffeine (1820)
• Nicotine (1828)
• Atropine (1833)
• Cocaine (1855)
• In the 19th century, the chemical structures of
many of the isolated compounds were
• In the 20th century, the discovery of
important drugs from the animal kingdom,
particularly hormones and vitamins.
microorganisms have become a very important
source of drugs
The knowledge of naturally occurring drugs
was transmitted by:
• In written form as papyri.
•On packed clay tablet.
•Printed herbal.
•Pharmacopeias and other works.
•Recently by computerized information.
• Pharmacognosy is the study of those natural
substances, principally plants that find use in
• Pharmacognosy:
It is the science of biogenic or nature-derived
pharmaceuticals and poisons
Crude drugs:
It is used for those natural products such as plants or part
of plants, extracts and exudates which are not pure
• Crude :Mean any product that has not been advanced
of improved in condition , by shredding , grinding ,
chipping , crushing , distilling or by any other process
except what is essential to its proper patching and to
the preventing of decay or deterioration during
• Drugs :Means those pure substances whether they
are natural or synthetic which have therapeutic or
medicinal properties and chiefly used as medicine or
as an ingredient in medicine .
• Crude drugs are used infrequently as therapeutic agents;
more often their chief principals are separated by various
means and are employed in a more specific manner.
These principles are known as Derivatives or extractive
and whether the extractive is a single substance or
mixture of substances, it is considered the chief
constituent of drug. The active principle are obtained by
Extraction which removes only those substances that can
dissolved in the liquid or mixture ( solvent ) and the
insoluble portion remains, known as Marc.
• Ethnobotany:
It is a broad term referring to the study of plants by
• Ethnomedicine:
It refers to the use of plants by humans as medicine
• Traditional medicine:
It is the sum total of all non-mainstream medical
practices, usually excluding so called “western”
Natural products: they can be
1. Entire organism (plant, animal, organism)
2. Part of an organism (a leaf or flower of a plant, an
isolated gland or other organ of an animal)
3. An extract or an exudate of an organism
4. Isolated pure compounds
Types of drugs derived from plants
1. Herbal drugs, derived from specific parts of a
medicinal plant
2. Compounds isolated from nature
3. Nutraceuticals, or “functional foods”
Pharmacognosy mainly concerned with
• Naturally occurring substance that have medicinal action.
• Natural and synthetic fibers and the surgical dressings.
• Pharmacognosy includes the study of other materials used
in pharmacy as flavoring agents, suspending agents,
disintegrants and other ingredients .
• Other fields which have naturally association are those of
poisonous and hallucinogenic plants, the raw material for
production of oral contraceptives, allergens, and
insecticides .
• Pharmacognosy closely related to both botany and
chemistry , so the beginning of the present century
Pharmacognosy has developed mainly on the
botanical side which concerned with the descriptions
and identification of drugs both in the whole state and
powder, and with their , history , commerce ,
collection , preparation and storage.
• Concerned with the elucidation of the biogenetic
pathway for the formation of medically active
secondary metabolites of plants .
• Dealing with the chromatography and other
procedure for identification and determination of
Geographical source or habitat
We have 3 sources :
• Indigenous plant: Those growing in their native
countries e.g. Aconitum – napellus is native to
central and southern Europe.
• Naturalized: e.g. Datura stramonium which
introduced into USA from Europe some introducing
by birds or ocean current or by man end animal .
• Cultivated: e.g. cinchona in America and Indonesia
which cultivated by man.
Official drugs :
The official drugs are natural substances which
recognized and included
1- Dried leaves of Mint plants and their active
constituents ( Menthone , Menthol , methyl acetate …)
these compounds are used to treat some stomach &
intestinal diseases .
2- Whole plant Catharanthus and their active
constituents (Vincristin and vinblastin ) these
compounds are used in treating Cancer diseases .
3- The juice or extract of un ripped fruit of poppy
plants (Papaver sp.) and its active constituents as (
Morphine ) used as narcotic analgesics .
4- Caffeine from the seeds of Coffee plants &
theophylline from leaves of tea plants are used
as stimulants .
Some drugs are natural preparations , that are
included in the official Pharmacopoeia , but
they are not found in the current issues ,
because those drugs by the time are being have
toxic effects ex:
1- Colchicum plant which used in treating a
gout disease .
2- Khat plant which used in Yamane country
to decrease sensation of fatigue and hungry.
Non – official drugs :
Such kind of drugs are never appear in official
pharmacopoeia .
So in general speaking a crude drug may have official
or unofficial status official title of crude drug it
appears in pharmacopoeia or other official reference
books & are given both in English & Latin .
while non official drugs are never appear in
pharmacopoeia .
Commerce in Drugs
• The commercial origin of a drug refers to its production and
its channels of trade .
• Drugs frequently bear a geographic name indicating the
country or region in which they are collected .These names
don’t necessarily reflect the area where the plant grows.
• Drugs are collected in all parts of the world. The
Mediterranean region yield more drugs than any other region
in the world but India, central Europe and America yield
numerous and valuable drugs.
• Neither the scientific name of the plant nor the commercial
name of them is necessarily an indication of the true habitat
of drug plants .
II. Value of natural products
Compounds from natural sources play four significant roles in
modern medicine:
1. They provide a number of extremely useful drugs that are
difficult, if not impossible, to produce commercially by synthetic
These include such diverse groups of compounds as the alkaloids of
the opium poppy, of ergot, and of solanaceous plants;
cardiotonic glycosides of digitalis, most of the antibiotics and all
of the serums, vaccines and related products.
II. Value of natural products
2. Natural sources also supply basic compounds
that may be modified slightly to render them
more effective or less toxic.
• example the numerous variations of the
morphine molecule.
3. Their utility as prototypes or models for synthetic
drugs possessing physiologic activities similar to the
H3 C
Salicylic Acid
4. Some natural products contain compounds that
demonstrate little or no activity themselves but
which can be modified by chemical or biological
methods to produce potent drugs not easily
obtained by other methods
Baccatin III  Taxol
Preparation of Drugs for commercial market:
1- Collection
2- Harvesting
3- Drying
4- Garbling
5- packaging, storage and preservation .
For proper collection we must notice:
• Collection of drugs from cultivated plant always
ensures a true natural sources and reliable product.
But it differ incase of collection of wild plant .
• Carelessness or ignorance some part of the collected
plant can result incomplete or partial substitution
special increase of difficulty to collect or natural
source was scarce.
• The proper time of collection is important because
the nature and quantity of constituents vary greatly
in some species according to the season. The most
advantageous collection time is when the part of the
plant that constitutes the drug is highest in its
content of active principles and when the material
will dry to give the maximum quality and appearance
The mode of harvesting varies with each drug. Some
drugs may be collected by hand labor, however when
the cost of labor is an important factor, the use of
mechanical devices is often more successful in
economic production of the drug. But some drugs,
the skillful selection of plant parts is important factor
(as in case of digitalis).
• The drying of the plant material by removing
sufficient moisture were :
• Ensure good keeping qualities .
• Prevent molding .
• Prevent the action of enzymes .
• Prevent the action of bacteria .
• Prevent chemical and other changes.
The benefit of drying will :
Fix the constituents.
Facilitate grinding and milling .
Converts the drug into a more convenient
form for commercial handling.
Successful drying involves two main Principles :
• Control of temperature.
• Regulation of air flow.
• The plant material can be dried either by the
sun or by the use of artificial heat. But with
some natural products, such as vanilla
fermentation or sweating will occurs which
will change the constituents, so such drugs
require special drying processes, usually called
• Garbling consists of the removal of extraneous
matter. Such as other parts of the plant, dirt
and added adulterants. This step is done
during collection, but also should carried out
after the drug was dried and before
packaging. Garbling may be done by
mechanical means in some case, but its
usually semiskilled operation.
Storage of crude drugs
• There are great differences in the stability of crude
drugs because of slow enzymic changes in the
• Drugs containing glycosides and esters are usually
less stable than those containing alkaloids.
• Drugs with essential oils deteriorate rather quickly
through evaporation, oxidation and polymerization
of the substances constituting the essential oil.
• Tannins on the other hand, have an almost
unlimited durability.
Packaging, storage and preservation :
• It is important to choose the type of packaging that
provides a good protection to the drugs .
• Usually leaves and herbs material are baled with
power balers into a solid compact mass that are sewn
into a burlap cover .
• Drug that are likely to deteriorate from absorbed
moisture (e . g . Digitalis, ergot )are packed in
moisture proof cans. Gums, resins and extracts are
shipped in barrels and boxes. Proper storage and
preservation are important factors in maintaining a
high degree of quality of the drug.
• Hard–packed bales, barks and resinous drugs usually absorb
little moisture. But leaf herb and root drugs that are not well
packed tend to absorb moisture which reaches 10 – 30 % the
weight of the drug.
• Excessive moisture not only increases the weight of the drug,
thus reducing the percentage of active constituents, but also
favors enzymatic activity and facilitates fungal growth.
• Light adversely affects drugs that are highly colored rendering
them unattractive and possible causing undesirable changes
in constituents. The oxygen of the air increases oxidation of
the constituents of drugs, especially when enzyme oxidase is
present. Therefore, the warehouse should be cool, dark and
well ventilated with dry air.
III. Production of natural drug products
1. Collection (wild)
2. Cultivation (commercial), collection, harvesting, drying,
garbling, packaging, storage and preservation e.g.
ginseng, ginkgo, peppermint
3. Fermentation
(Recombinant DNA
technology or Genetically engineered drugs)
4. Cell-culture techniques
5. Microbial transformation
6. Biologics (prepared from the blood of animals)
IV. The role of natural products in drug
1. Combinatorial chemistry
2. High-throughput screening of natural products
3. Combinatorial biosynthesis
4. Ethnopharmacology
V. General principles of botany:
morphology and systematics
How to define a pharmaceutical plant-derived drug from
the botanical point of view ?
a botanical drug is a product that is either:
Derived from a plant and transformed into a drug by drying
certain plant parts, or sometimes the whole plant, or
1. Obtained from a plant, but no longer retains the structure of
the plant or its organs and contains a complex mixture of
biogenic compounds (e.g. fatty and essential oils, gums,
resins, balms)
• isolated pure natural products are thus not
“botanical drugs”, but rather chemically defined
drugs derived from nature.
 the following plant organs are the most important, with the
Latin name that is used, for example in international trade, in
1. Aerial parts or herb (herba)
2. Leaf (folia)
3. Flower (flos)
4. Fruit (fructus)
5. Bark (cortex)
6. Root (radix)
7. Rhizome (rhizoma)
8. Bulb (bulbus)
• The large majority of botanical drugs in current
use are derived from leaves or aerial parts.
• A plant-derived drug should be defined not only
in terms of the species from which it is obtained
but also the plant part that is used to produce the
dried product. Thus, a drug is considered to be
adulterated if the wrong plant parts are included
(e.g. aerial parts instead of leaves)
• It is the science of naming organisms and their
correct integration into the existing system of
• The names of species are given in binomial
form: the first part of the name indicates the
wider taxonomic group, the genus; the second
part of the name is the species.
Papaver somniferum L.
• Species: somniferum, here meaning ‘sleepproducing’
• Genus: Papaver (a group of species, in
this case poppies, which are
closely related)
• Family: Papaveraceae (a group of genera
sharing certain traits)
• L.: indicates the botanist who provided the
scientific description of the species
assigned the botanical name
and who
Morphology of higher plants
1. Flower
It is the essential reproductive organ of a plant.
For an inexperienced observer, two characteristics of a
flower are particularly noteworthy: the size and the color
Although the flowers are of great botanical importance,
they are only a minor source of drugs used in phytotherapy
or pharmacy e.g. chamomile, Matricaria recutita L.
(Asteraceae )
2. Fruit and seed
• The lower plants, such as algae, mosses and ferns, do
not produce seeds
Gymnosperm and Angiosperm
• Gymnosperm: they are characterized by seeds that are
not covered by a secondary outer protective layer, but
only by the testa – the seed’s outer layer
• Angiosperm: the seeds are covered with a specialized
organ (the carpels) which in turn develop into the
• Drugs from the fruit thus have to be derived
from an angiosperm species
• Fruits and seeds have yielded important
phytotherapeutic products, including:
 Fruit
Caraway, Carum carvi L. (Umbelliferae)
 Seed
(white) mustard, Sinapis alba L. (Brassicaceae)
3. Leaves
• The function of the leaves, as collectors of the sun’s
energy and its assimilation, results in their typical
general anatomy with a petiole (stem) and a lamina
• A key characteristic of a species is the way in which the
leaves are arranged on the stem, they may be:
1. Alternate
2. Distichously
3. Opposite
4. Decussate
5. Whorled
• The form and size of leaves are essential
characteristics e.g. oval, oblong, obovate,
rounded, linear, lanceolate, elliptic, spatulate,
cordate, hastate or tendril
• The margin of the leaf is another characteristic
feature e.g. entire, serrate, dentate, sinuate,
ciliate or spinose
• Numerous drugs contain leaf material as the main
component. e.g.
Atropa belladonna L.
4. Bark
• The bark as an outer protective layer frequently
accumulates biologically active substances e.g.
Red cinchona, Cinchona succirubra L.
• No stem-derived drug is currently of major
5. Rhizome and root drugs
• Underground organs of only a few species have
yielded pharmaceutically important drugs e.g.
1. Sarsaparilla, Smilax regelii
2. Korean ginseng, Panax ginseng
6. The bulbs and exudates
1. Garlic, Allium sativum L. (Liliaceae)
2. Aloe vera L. (Asphodelaceae)
Animal drugs:
• Animal drugs production from wild or
domesticated animals. Wild animal (whale,
must deer) or fished (cod and halibut) when
drugs consist of insects. Either collected from
wild insect (cantharides) or cultivate them by
furnish the insect with food and shelter
maintain optimum condition for their
propagation (honeybee) .
• Drugs such as lanolin and milk products as
wells as hormones , endocrine products and
some enzymes , are obtained from
domesticated hogs, sheep or cattle , the
slaughter house is the usual source of
glandular products of enzymes.
• Processing and purification of the animal drugs
vary with the individual drug.
Evaluation of drugs:
• To evaluate drugs mean to identify it and to determine its
quality and purity.
• The identity of a drug can be established by its actual collection
form a plant or animal that has been identified, another
method of identification is the comparison of a representative
unknown sample to a published description of the drug and
the authentic sample.
• Quality refers to the value of the drug i.e. the count of
medicinal principles or active constituents present e.g.
carbohydrate, glycosides, tannins, lipids, oils, steroids, alkaloids
…etc.) A high grade of quality in a drug is of primary, and effort
should be made to obtain and maintain this high quality.
The evaluation of a drug involves a number of
methods that may be classified as follows
Biologic or pharmacologic.
1. Organoleptic: refers to evaluation by means of
organs of sense and include the macroscopic of the
drug, its odor, test, occasionally the sound or snap of
the fracture, and the fell of the drug to touch.
2. Microscopic characteristics are important.
3. Pharmacologic activity of certain drugs have been
applied to their evaluation and standardization.
Assay on living animals as well as on intact organs
often indicate the strength of the drug or its
preparations , when living organism are used the
assay are called bioassays.
4. Chemical methods of evaluation crude drugs
and their products are widely and they were
represents the best methods of determining the
official potency.
5. Physical: the application of typical physical
constants to crude is rare, but physical
constants are extensively applied to the active
principles drugs. Such as alkaloids, volatile
oils, fixed oils and others.
Classification of Drugs:
• Drugs may be classified according to:
1. Alphabetical: Using either Latin or English names, the drugs
are arranged alphabetical order.
2. Taxonomic: The drugs are arranged according to the plants
from which they were obtained in phyla, orders, families,
genera and species.
3. Morphological : Here the drugs are divided into groups such
as the : leaves , flowers, fruits , seeds , herbs and entire
organism , woods , barks rhizomes and roots ( organized drugs
) dried lattices , extracts gums, resins, oils , fats and waxes (
unorganized drugs ).
4. Pharmacological or therapeutic: Grouping the drug according
to the pharmacological action of their most important
constituent or their therapeutic uses.
5. Chemical or Biogenetic: Here the drugs the divide into groups
according to their most important constituents. E.g. alkaloids,
glycosides, volatile oils …..etc. or according to the
biosynthetic path ways by which the active constituents are
• Each of the methods of classification has advantages and
Chemistry of drugs:
• The living organism may be considered a biosynthetic
laboratory not only for chemical compounds ( carbohydrate ,
proteins , fats ) that are utilized as food by humans but also for
a number of compounds ( glycosides , alkaloids , terpenes….)
that exert a physiological effect.
• These chemical compounds give plant and animal drugs their
therapeutic properties. Drugs are used as such in their crude
form or they may be extracted. The resulting principals being
employed as a medicinal agents and they are called active
• These active constituent are differentiated from inert
constituents (cellulose, lignin suberin, and cutin in addition,
starch, albumin, coloring matters and other substances) which
also occur in plant and animal drugs.
Often the presence of inert substances may affect the
absorbability or potency of the active constituents. To remove
the undesirable effects of inert matter in the crude drug or its
preparation, active principle are extracted, crystallized and
purified for better therapeutic uses.
• Active constituent may be divided into two classes:
• pharmacologically active
and Pharmaceutically active.
• Pharmacologically active which are responsible for the
therapeutic activity of drug, either single or mixture of
principles (e.g. of single: sugars, starch, plant acids, enzyme,
glycosides, steroids, alkaloids, proteins, hormones and
vitamins). The mixture: e.g. volatile oils, fats waxes , fixed oil,
resins, oleoresins, oleo gum resins and balsams.
• Pharmaceutical active constituent those which are used in
pharmacy as diluents, disintegrants and other ingredients.
• The secondary active constituents of plant drugs are
influenced by 3 principle factors:
• heredity ( genetic composition )
• Ontogeny (stage of development).
• Environment.
1. Genetic effect induces both quantitative and qualitative
• Plants of the same species that resemble one another closely
inform and structure may be quite different in genetic
composition. This often results distinct differences in chemical
composition, particularly with references to secondary
constituents. Such plants are said to belong to different
chemical races, e.g. papaver somniferum contain alkaloid,
Morphine while papaver rhoeas have no morphine alkaloid
2. Ontogeny plays a significant role in the nature of the active
constituent found in medicinal plants. It might be expected that
concentration of secondary metabolites increase with the age of
plant. It is not generally appreciated that the identity of these
constituent may also vary according to the stage of
development. The cannabidiol alkaloid content of cannabis
sativa reaches a peak early in the growing season then begins to
decline, when this decline occur , the concentration of
tetrahydrocannabinol alk. begins to increase and continues
increasing until the plant approach maturity. In the opium poppy,
papaver somniferum the morphine contents of the capsules is
highest within 2-3 weeks after flowering and if these poppy is
harvested early, codeine are predominate on the other hand, if
harvesting was delayed the morphine decomposed.
3. Environmental factors : Can produce variation in
secondary constituents include soil, climate and
method of cultivation, for example, many alkaloid
containing plants accumulate higher concentrations
of such constituents in moist than in arid lands. This
may actually related to the soil which is usually poor
in nitrogen sources which are usually required for a
good yield of alkaloids.
• really this is not necessarily the case with volatile oil
bearing plants, excess nitrogen was not necessarily
cause an increase in the their yields.
New bioassays:
• In fractionating extracts, to determine the identity of the active
constituent, we need simple bioassay procedures.
• Researchers have reported success with a simple bioassay utilizing brine
shrimp. The eggs of this creature are available in the dry state from pet
shops where they are stocked as food for tropical fish, after hatching in a
brine solution. The shrimp are exposed to different concentration of the
test material, LC50 (median lethal concentration) value in mg is calculated.
It has been determined that the activities of a broad range of compounds
are manifested as toxic to the shrimp. The method is rapid, reliable, and
inexpensive and may be applied in house by chemists, botanists or others.
For these reasons, it has been successfully utilized in several studies
involving the screening of large numbers of plant species for compounds
with useful biologic or pharmacologic activities.
• Another procedure is potato-disc. This involve observation for
the inhibition of crown gall tumors, induced potato disc by
Agrobaterium tumefaciens and using various plant extracts or
constituents, being screened in a preliminary fashion for their
anti cancer potential .
• Results have been encouraging and have correlated
statistically with other more elaborated and costly cell culture
procedures, at least for certain kinds of antitumor activity. Old
fashioned pregnancy test, involved injecting the patients urine
into a rabbit and then sacrificing the animal to examine the
condition of its ovaries. While now a day women suspecting
pregnancy simply dips a plastic strip bearing certain
monoclonal antibodies into a urine specimen and look for
color change.
New analytical methods:
• Our analytical capabilities also will be improved because of their complex
nature of plants and difficulty to fractionate for the purpose of isolation
and identification of active constituents.
• Certain experiment done by using selective solvent extraction as out lined
by Dragendroff in the 1880, gave away in this century to adsorption
chromatography , which in turn take way to ion exchange , paper partition
and thin layer technique before developing into high pressure liquid
chromatography (HPLC) and gas chromatography Coupled with mass
spectrometry, this last methodology has been extremely useful. So called
multiple stage mass spectrometry has now come upon the hope
identification and quantitation of nanogram quantities, of active
constituents in tissue sample approximating 1 mg without prior extraction
or purification.
• Other powerful techniques for structural
determination of complex plant constituent include X
ray crystallography and nuclear magnetic resonance
(NMR) spectroscopy in its several variation.
• It is evident the further study in all of those
techniques couple with some unexpected new
developments, will lead to the ultimate (black box ).
A few milligrams of plant tissue placed in one side
will be converted into a print out, listing all the
constituent interest and their concentration in
Culture Techniques:
• One of the present problems in producing
plant drugs is securing adequate amounts of
the proper material. Collection in quantity of
properly identified sometimes scarce, wild
growing plants scarce wild growing plants is
becoming increasingly difficult; the difficulty
will be over come in these years by a plant
culture methodology.
• Present limitation of plant cell culture
techniques include:
• Slow growth.
• Expensive media.
• Tendency to store desired metabolites in the
tissues rather than to exert them into the
media, where they are easily recovered.
• Such producing is now economically feasible
only when the compounds produced are both
costly and unique as plant products.
• Some compounds produced in high yields in
such cultures include diosgenin glycoside from
the plant discorea and serpentine alk. from
catharanthus roseus .
• Techniques will be greatly improved as a result of new
information regarding factors influencing the formation of
secondary plant constituents.
• Research has shown pharmaceutically desirable secondary
metabolites natural are phytoalexins, which synthesized only
when the plants are subject to physical, chemical,
microbiological, or fungal damage.
• Example: gossypol in Gospium arboreum, increase yield of
these compounds resulted from the addition of heat. The yield
of other constituents like codeine and morphine in the plant
papaver somniferum cell suspension culture are greatly
improved by similar methods.
• Numerous studies which done have shown have that stress
conditions in plant cell suspension culture , such as interaction
with an appropriate pathogen , can induce the formation of
secondary constituent increase that such constituent are not
produced in quantity under normal conditions.
• This approach is currently employed commercially in
production of quinine.
• Alternative methods will be developed for plant unable to
accumulate large cell masses in terminate time in such cases
isolation and immobilization; of enzyme of intact plant cells
seem reasonable.
• Another approach to alter the slow growth rate in plant cell –
suspension culture is to transfer plant genes, which code for
the enzymes catalyzing the desired biosynthetic reactions,
into a bacterial or fungal cell.
• Many gene products are required to products desired
secondary metabolites.
We hope in the future that the manipulation of plant cells,
plant genes and plant enzymes rather than the plant
themselves should provide us with useful medicinal agents .
New plant drugs : for healing some
types of diseases
• a new drugs which useful to help diseases which still remain
not cures : these diseases are :
1. Viral diseases such as herpes (genitals, simplex and zoster)
AIDS, and cancers.
2. Diseases of unknown etiology, including arthritis, some
cancers and muscular dystrophy .
3. Self inflicted diseases such as alcoholism drug dependency,
smoking and stress.
4. Genetic diseases, ranging from cystic fibrosis and hemophilia
to sickle – cell disease.
• In addition improve drugs need to be developed for
1.The control of symptoms such as pain.
2.Treatment of elevated cholesterol level , diabetis and
3.General susceptibility to disease of various kinds .
4. Infections and non infections diseases
• In recent years, the concept of immunotherapy (stimulation of
the body to develop and improve its own defenses) has
developed from a very promising filed of drug therapy.
• Another area in which plant principles are exhibiting
considerable promise is that of hepatoprotective drugs. Such
agents are urgently needed not only to protect the liver from
infections such as viral hepatitis but also to help and prevent
damage form ingested toxins ranging from amotoxin to ethyl
• Silymarin, a mixture of flavonolignans obtained from the seeds
of the plant silybium marianum which is currently marketed in
Europe and used for these purposes with success .