3. Pharmacognosy
• Pharmacognosy is the study of medicines
derived from natural sources.
• The American Society of Pharmacognosy
defines pharmacognosy as "the study of the
physical, chemical, biochemical and biological
properties of drugs, drug substances or
potential drugs or drug substances of natural
origin as well as the search for new drugs from
natural sources”
4. Pharmacognosy
• Although pharmacognosy is principally concerned with
plant materials, there are a small number of animal
products which are traditionally encompassed within the
subject;
• Examples:
– Produced from wild (whale, musk, deer)
– Fish (cod and halibut)
– domesticated animals (hog, sheep, cattle) –lanolin and milk
products, hormones, endocrine prods, and some enzymes
– Wild insects (cantharides)
– Cultivated (beeswax)
• Marine organisms, both plant and animal, with potent
pharmacological actions are receiving increasing attention
in the search for new drugs.
5. Pharmacognosy
• Materials having no pharmacological action
which are of interest to pharmacognosists are
natural fibres, flavouring and suspending
agents, colourants, disintegrants, stabilizers
and filtering and support media.
• Other areas that have natural associations
with the subject are poisonous and
hallucinogenic plants, allergens, herbicides,
insecticides and molluscicides.”
6. Pharmacognosy
• Recently it includes:
– Modern isolation techniques
– Pharmacological testing procedures to prepare
purified substances
– Cultivation and propagation by tissue culture
7. The history of natural products in
medicine
• A great proportion of the natural products are used as
drugs
• The study of drugs used by traditional healers is an
important object of pharmacognostical research
15. Ibn Al bitar (1148-1197)
” الجامعلمفرداتاألدويةواألغذية “
16. The era of European exploration overseas
(16th and 17th century)
17. History
• The word ‘Pharmacognosy’ is derived from:
– pharmakon ‘a drug’ (Greek)
– gignosco ‘ to acquire knowledge of’ (Greek)
– or cognosco ‘to know about’ (Latin)
• The term "pharmacognosy" was used for the first
time by the Austrian physician Schmidt in his
Lehrbuch der materia medica in 1811 and in 1815
by Crr. Anotheus Seydler in a work titled Analecta
Pharmacognostica.
18. History
• It is a recognised fact that in the historical development of
any subject the role of certain individuals is of considerable
importance.
• The first British pharmacognosist was Jonathan Pereira
(1804–1853), who as the first teacher of the subject gave it
its pharmaceutical basis. He may be considered as the
founder of British pharmacognosy.
• Daniel Hanbury (1825–1875) was the most outstanding
applied pharmacognosist while the contribution made by
E. M. Holmes (1843–1930) as an applied pharmacognosist
stands out both in quality and quantity.
• Dr. Chandrakant Kotate, Father of Indian Pharmacognosy
19. The era of pure compounds
• Isolation of morphine from opium (1806)
• Strychnine (1817)
• Quinine and caffeine (1820)
• Nicotine (1828)
• Atropine (1833)
• Cocaine (1855)
20. • 19th century: the chemical structures of many
of the isolated compounds were determined
• 20th century: the discovery of important
drugs from the animal kingdom, particularly
hormones and vitamins
• microorganisms have become a very
important source of drugs
21. Pharmacognosy: Fields
• Medical ethnobotany: the study of the traditional
use of plants for medicinal purposes;
• Ethnopharmacology: the study of the
pharmacological qualities of traditional medicinal
substances;
• Study of phytotherapy (the medicinal use of plant
extracts);
• Phytochemistry, the study of chemicals derived
from plants (including the identification of new
drug candidates derived from plant sources).
22. Pharmacognosy: Fields
• Zoopharmacognosy, the process by which
animals self-medicate, by selecting and using
plants, soils, and insects to treat and prevent
disease
• Marine pharmacognosy, the study of
chemicals derived from marine organisms.
23. Phytochemicals
• All plants produce chemical compounds as
part of their normal metabolic activities.
These phytochemicals are divided into
• (1) Primary metabolites such as sugars and
fats, which are found in all plants;
• (2) Secondary metabolites—compounds
which are found in a smaller range of plants,
serving a more specific function
24. Phytochemicals
• some secondary metabolites are toxins used to
deter predators and others are pheromones used
to attract insects for pollination.
• It is these secondary metabolites and pigments
that can have therapeutic actions in humans and
which can be refined to produce drugs—
examples are inulin from the roots of dahlias,
quinine from the cinchona, morphine and
codeine from the poppy, and digoxin from the
foxglove.
25. Phytochemicals
• Plants synthesize variety of phytochemicals
but most are derivatives of a few biochemical
motifs:
• Alkaloids
• Phenolics
• Glycosides
• Terpenes
26. Phytochemicals
• Alkaloids are a class of chemical compounds
containing a nitrogen ring.
• Glycosides is a molecule in which a sugar is
bound to a non-carbohydrate moiety, usually a
small organic molecule.
• Polyphenols (also known as phenolics) are
compounds contain phenol rings.
• Terpenes and terpenoids are the primary
constituents of resin, essential oils of many types
of plants and flowers.
27. Alkaloids
• Examples are
– the local anesthetic and stimulant cocaine;
– the psychedelic psilocin;
– the stimulant caffeine, nicotine;
– the analgesic morphine;
– the antibacterial berberine;
– the anticancer compound vincristine;
– the antihypertension agent reserpine;
– the cholinomimetic galantamine;
– the spasmolysis agent atropine;
– the vasodilator vincamine;
– the anti-arhythmia compound quinidine;
– the anti-asthma ephedrine;
– the antimalarial drug quinine.
28. Classification
• Vegetable drugs can be arranged for study
under the following headings:
– Alphabetical
– Morphological
– Taxonomical
– Pharmacological / Therapeutic
– Chemical
29. Alphabetical
• Either Latin or vernacular names may be used.
• This arrangement is employed for dictionaries,
pharmacopoeias, etc.
• Although suitable for quick reference it gives no
indication of inter-relationships between drugs.
30. Morphological
• Drugs are arranged according to their
morphological or external characters of the plant
parts or animal parts, i.e. which part of the plant
is used as a drug
– Organized drugs : obtained from the direct parts of
the plants and containing cellular tissues
– e.g. leaves (digitalis, senna, belladona), flowers (clove,
saffron), fruits (amla, cardamom, cumin), seeds
(ispaghula, linseed, physostigma), herbs (ergot, vinca),
barks (cinchona), rhizomes and roots (aconite,
ginseng, ipecac, rauwolfia), hair & fibres (flax)
31. Morphological
– Unorganized drugs: prepared from plants by some
intermediate physical processes such as incision, drying or
extraction with a solvent and not containing any cellular
plant tissues
– e.g. latex (opium), dried juice (aloe), extracts (agar,
catechu, pectin), waxes (beeswax), gums (acacia,
guargum), resins (benzoin, colophony, tolu balsam),
volatile oil (turpentine, cinnamon, peppermint, clove),
fixed oils & fat (arachis, castor, olive, cod liver),
• Advantage: More convenient for practical study
especially when the chemical nature of the drug is not
clearly understood
• Disadvantage: there is no correlation of chemical
constituents with the therapeutic actions
32. Taxonomic
• Drugs are arranged according to the plants from
which they are obtained, in kingdom,
subkingdom, division, class, order, family, genus
and species
– Advantage: It allows for a precise and ordered
arrangement and accommodates any drug without
ambiguity; helpful for studying evolutionary
developments
– Disadvantage: does not correlate in between the
chemical constituents and biological activity of the
drugs
33. Taxonomic
• Class
– Angiospermae (Angiosperms): plants that produce
flowers
– Gymnospermae (Gymnosperms): Plants which do not
produce flowers
• Subclass
– Dicotyledonae (Dicotyledons, Dicots): plants with two
seed leaves
– Monotyledonae (Monotyledons, Monocots): plants
with one seed leaf
34. Taxonomic
• Superorder: A group of related plant families,
classified in the order in which they are
thought to have developed their differences
from a common ancestor
• Each superorder is further divided into several
orders; the names of the orders end in -ales
35. Taxonomic
• Family
– Each order is divided into families
– These are plants with many botanical features in
common, and are the highest classification normally
used.
– The names of the families end in –aceae
• Subfamily
– The family may be further divided into a number of
subfamilies, which group together plants within the
family that have some significant botanical
differences.
– Subfamilies end in -oideae
36. Taxonomic
• Genus
– Part of the plant name that is most familiar; the
normal name that you give a plant
• Papaver (poppy)
• Arachis (peanut)
• Species
– Level that defines an individual plant
– The name describes some aspect of the plant – the
color of the flowers, size or shape of the leaves, or it
may be named after the place where it was found.
– Should be written after the genus name, in small
letters
37. Pharmacological/Therapeutic
• This classification involves the grouping of drugs
according to the pharmacological action of their
most important constituent or their therapeutic
use.
• Advantage: More relevant and mostly followed
method
• Disadvantage: Drugs having different action on
the body get classified separately in more than
one group that causes ambiguity and confusion
44. Chemical
• Crude drugs are classified depending upon the
active constituents
• Irrespective of the morphological or taxonomical
characters, the drugs with similar chemical
constituents are grouped together
• Advantage: it is a popular approach for
phytochemical studies
• Disadvantage: ambiguities arise when particular
drugs possess a number of compounds belonging
to different groups of compounds.
45. Chemical
Chemical Constituent Group
• Alkaloids - Cinchona, Datura, Vinca, Ipecac, Nux vomica
• Glycosides - Senna, Aloe, ginseng, Digitalis
• Carbohydrates & its derivatives - Acacia, Starch, Isabgol
• Volatile oil - Clove, Coriander, Fennel, Cinnamon,
Cumin
• Resin and Resin Combination - Benzoin, Tolu Balsam,
Balsam of Peru
• Tannins - Catechu, Tea
• Enzymes - Papain, Casein, Trypsin
• Lipids - Beeswax, Kokum butter, Lanolin
46. 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)
47. The role of natural products in drug discovery
1. Combinatorial chemistry
2. High-throughput screening of natural products
3. Combinatorial biosynthesis
4. Ethnopharmacology
48. Scope of Pharmacognosy
• 1. ISOLATION OR ANALYSIS OF PHYTOCHEMICAL :
• Eg ; Strong acting substances such as glycosides from digitalis
leaves,
• Alkaloids from the plants of Belladonna, Hyocyamus,
Rauwlofia
• Morphine and other alkaloids from the plant opium were
isolated and clinical uses studied
49. 2. STRUCTURE ACTIVITY RELATIONSHIP :
Eg : Tubocurarine and Toxiferine from curare plant
have muscle relaxant properties because of
quaternary ammonium groups.
The hypotensive and tranquillizing actions of
reserpine are due to the trimethoxy benzoic
acid
50. 3. DRUGS OBTAINED BY PARTIAL SYNTHESIS OF NATURAL
PRODUCTS:
Eg : Preparation of Steroid hormones from diosgenin by
acetolysis and oxidation and further preparation of
cortisone by microbial reactions.
4. NATURAL PRODUCTS AS MODELS FOR SYNTHESIS OF NEW
DRUGS :
Eg: Morphine is the model of a large group of potent drugs .
Cocaine for local anaesthetics
Atropine for certain spasmolytics
51. 5. DRUGS OF DIRECT THERAPEUTIC USES :
• Among the natural constituents which even now cannot be
replaced are important group of antibiotics, steroids, ergot
alkaloids, vincristine etc
6.CULTIVATION AND COLLECTION OF MEDICINAL PLANTS :
• clove, cinchona , cinnamon, senna, opium, etc
7. PREPARATION OF HERBAL FORMULATIONS :
• churnas, asvas, aristas, leha, etc
8. DEVELOPMENT OF TISSUE CULTURED PLANTS
52. Biological method of evaluation
SIGNIFICANCE:
1.The method is generally used when standardization is not
done satisfactorily by chemical or physical methods
2.When the quantity of the drug /sample are very less, then the
drugs are evaluated by biological methods
These methods are performed on living animals, isolating
living organ and tissue, animal preparation, and
microorganism
( Bioassay)
53. Following method is used as
1.Anti inflammatory activity
2.Analgesic activity
3.Antipyretic activity
4.Anti ulcer activity
5.Antidiabetic activity
6.Anthelmintic activity on earth worms
7.Cardiac activity- on frog and pigeon
8.Microbiological methods- living bacteria, yeast, molds are used
for the assaying vitamins and to determine the activity of
antibiotic drugs
54. Why do we need plants?
1. Source of drug molecules
– They provide a number of extremely useful drugs
that are difficult, if not impossible, to produce
commercially by synthetic means
• Most drugs can be synthesised
• Still more economical to use the plant
Papaver opium -> morphine, codeine (strong analgesic)
Ergot fungus –> ergotamine (migraine), ergometrine (direct action
on uterine muscle)
55. Why do we need plants?
2. Source of complex molecules that can be modified to
medicinal compounds
• Example:
Soya: saponins -> steroids
– 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
– Supply basic compounds that may be modified slightly to
render them more effective or less toxic
56. 3. Their utility as prototypes or models for synthetic
drugs possessing physiologic activities similar to the
originals
COOH
HO
COOH
OH3C
O
H3C COOH
CH3
CH3
Salicylic Acid Aspirin
Ibuprofen
57. Morphine:
No better painkiller. Once structure worked out wanted
to improve it. What is required?
Diacetylmorphine (heroin):
OH group -> O-O-diacetyl. Still addictive?
Codeine:
Methylate hydroxyl phenolic; O-Me. 1/5 analgesic
capacity of morphine, useful to suppress cough reflex
Dihydromorphinone:
Reduced =, oxidised 2y alc. Potential analgesic.
Source of compounds to use as templates
for designing new drugs
58. Dihydrocodeine:
Me-ether of previous. More powerful than codeine,
less than morphine.
Dextromethorphan:
Good against cough reflex
Is lower ring necessary?
Pentazocin
Phenazocine
Is middle ring needed?
Pethidine
Methadone
59. Why do we need plants?
4. Source of toxic molecules
• To study the way the body responds to their
pharmacological use
• Investigating pharmacological mechanisms
picrotoxin – nerve conduction
60. Why do we need plants?
• 5. Source of novel structures
• these might never be thought of
Catharanthus periwinkle -> vincristine (alkaloid dimer)
61. Why do we need plants?
• 6. Source of plant drugs
• As a powder or extract
• The pure compound is often not isolated because:
» Active ingredient is unknown
» Active ingredient is unstable
» Isolation process is too costly
62. Future
• About 500,000 species of higher plants on earth
• <10% investigated and only for one activity
• Huge potential in plant kingdom
