DR JOSEPH ADUSEI SARKODIE

DEFIN I TION

The term Pharmacognosy has been derived from the 2
Greek words:
 i) pharmakon, which means a drug &
 ii) gnosis, which means knowledge of or gignosco, which means to acquire knowledge of.

Thus the full meaning of the term Pharmacognosy is
`knowledge of drugs’ or `to acquire knowledge of drugs’.

W HAT IS P HARMACOGNOSY ?
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Is the study of Physical, Chemical,
Biochemical and Biological properties of drugs or substances from natural origin

HYSICAL
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Form
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Odour
Colour pH
Melting point
Solubility

HEMICAL
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Isolation-CC
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Composition
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Identification

IOCHEMICAL
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Characterisation-methods used to characterise the chemical bonds present
NMR
HPLC
MS

IOLOGICAL
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Pharmacology
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Beneficial
Adverse effect of substance

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Pharmacognosy is one of the main disciplines in pharmacy
Others include:
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Pharm. Chem
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Pharmaceutics and Microbiology
Pharmacology
Clinical and Social pharmacy

I NTRODUCTION TO PHARMACOGNOSY
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Pharmacognosy is an applied science which is concerned with acquiring knowledge of crude drugs by the application of various scientific disciplines
Pharmacognosy deals with NATURAL products and is described as: the study of medicinal or therapeutic agents of natural origin, i.e.
Plants
Animals
Mineral sources
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It also includes the study of their history, distribution, cultivation, collection, preparation, identification, evaluation, preservation & commerce

O RIGINS AND HISTORY OF P HARMACOGNOSY
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Pharmacognosy is regarded as the mother of all sciences
History of Pharmacognosy represents the history of pharmacy and medicine.
Pharmacognosy had its origin in the health related activities of the most primitive human race of the remote past.
The early man sought to alleviate his sufferings of illness and injuries by using plants.
Studies of the use of medicinal plants is pre-historic
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Discovery of the medicinal properties of plants and other natural products started in the very early days of man’s existence.

ETHODS
SED
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Trial and error
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Observation of animal instinct on plants
Divination
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By superficial resemblance between the plant parts & the affected organs, that is, by examining the
“Signature of Nature”
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By accidental discovery

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These contributed to the acquisition on knowledge and conservation of the medicinal properties of natural products
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Such pieces of information laid the foundation for medicine.

H
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Records of medicinal properties of plants dates back to creation
Ezekiel 47:12
Earliest known medical document is a 4000-year-old
Sumerian clay tablet that recorded plant remedies for various illnesses (6 th -2 nd millennium B.C.)
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Papyrus Ebers from Egypt (1550 B.C.)

GYPTIANS
(E
, 1550 BC)

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Other documented history is that of the use of
Chaulmoogra oil form spp of Hydnocarpus, which was known to be effective in the treatment of leprosy.
Recorded in the pharmacopoeia of the Emperor Shen
Nung of China between 2730 B.C. and 3000B.C
Biblical references.

A UTHORS OF ANTIQUITY
H IPPOCRATES (460-377 BC)
“T HE F ATHER OF M EDICINE ”(400 HERBAL
REMEDIES
)

T HEOPHRASTUS (370-287 B.C.)
H ISTORIA P LANTARUM

P EDANIUS D IOSCORIDES (40-80 AD)
“D E M ATERIA M EDICA ” (600 MEDICINAL PLANTS )

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Galen (130-201 A.D.)
Introduced dosage forms and standardised dosages.
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Dale’s Pharmacologia separated Therapy from Preparation of drugs. Which led to founding of Medicine and Pharmacy as two separate professions.

P HARMACOGNOSY
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This term was introduced by C.A. Seydler, a
German medical student in 1815.
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Pharmakon- drug/medicine
 gnosis- knowledge
 gignosis- to acquire knowledge
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Pharmacognosy therefore means knowledge of drugs.

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Alexander Tschirch (1856- 1939), regarded as one of the founders of Modern
Pharmacognosy.
Defined Pharmacognosy as the science whose object is to study scientifically drugs of plant and animal origin from every view point with the exception of their physiological action.

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Pharmacognosy relates largely to botany and organic chemistry and covers
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Origin of plant drugs
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Source and distribution- Botanical and Geographical sources
Cultivation
Collection and Preparation for the market
Identification- Botanical and chemical
Constituents
Use of plant drugs

C ONSTITUENTS OF MEDICINAL PLANTS
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Plants contain chemical compounds
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Some of these compounds are responsible for the effectiveness of the plants as medicinal agents these compounds are described as
CONSTITUENTS

I MPORTANCE / ROLES OF PLANT
CONSTITUENTS
1.
2.
3.
4.
Some take on characteristic histological features useful for plant identification
Produce characteristic colours with reagents
(useful for identification)
Influence factors for preparing plant drugs for the market
Time and temperature for drying (E.g. cardiac glycosides and essential oils)

5. Storage conditions (E.g. Cascara increases in medicinal vale with long storage)
6. Useful in biosynthetic studies
7. Important for pharmacological and therapeutic activity
8. Useful as excipients and flavouring agents

T YPES OF CONSTITUENTS

1.
These range from simple compounds, e.g. sugars, amino acids to complex molecules, e.g.Steriods
and Vitamins
Active constituents- those that are responsible for activity, E.g. tannins and alkaloids
2.
Inactive/inert constituents- these are present in the plants but do not produce any therapeutic activity. E.g. lignin, cellulose and suberin

F ORMATION OF CONSTITUENTS
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Simple compounds, e.g. sugars, amino acids, fatty acids, plant acids are produced as a result of the plant’s basic metabolism
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Products obtained are referred to as PRIMARY
PLANT METABOLITES.
These give rise to more complex products called
SECONDARY PLANT METABOLITES, through biological and biochemical processes called
BIOSYNTHESIS or BIOGENESIS
Most active plant constituents are secondary plant metabolites

LASSES OF CONSTITUENTS COMMONLY
ENCOUNTERED
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Carbohydrates
Compounds made up of C, H, O as polyhydroxy aldehyde or ketone alcohols, with H and O usually present in ratio 2:1.
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May be divided into;
1.
SUGARS, e.g. glucose, sucrose, etc
2.
NON-SUGARS, e.g. Starch, cellulose, gums

Glycosides
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Compounds which on hydrolysis breakdown into:
A SUGAR portion
And NON-SUGAR portion called AGLYCONE
There are various classes of glycosides including
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Cyanogenetic glycosides- yield HCN on hydrolysis
Anthraquinone glycosides
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Cardiac glycosides- have activity on heart muscles
Saponin glycosides- froth forming

Tannins
Lipids
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Esters of long chain fatty acids and alcohols
Include fixed oils, fats and waxes
Volatile/essential oils
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Odoriferous principles found in plants
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Volatile in steam and
Made up of terpene derivatives

Alkaloids
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Nitrogenous compounds usually heterocyclic, basic character with pharmacological activity
Steroids
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Derivatives of cyclopentanophenanthrene skeleton

TERMINOLOGIES
Preparations
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Decoction: A tea made from boiling plant material, usually the bark, rhizome, roots in water.
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Infusion: A tea made by pouring water over plant material (usually dried flowers and leaves, though fresh material may also be used), then allowed to steep. The water is usually boiling, but cold infusions are also an option.

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Tincture: An extract of a plant made by soaking herbs in a dark place with a desired amount of either alcohol or vinegar for a period of time. The liquid is strained from the plant material and then used therapeutically.
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Poultice: A therapeutic topical application of a soft moist mass of plant material (such as bruised fresh herbs) on the skin

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Medicinal plant: Any plant which in whole or part contains substances that can be used for therapeutic purposes or which are precursors for the synthesis of useful drugs.
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Herbal medicine: The study or use of medicinal plants to prevent and treat diseases and ailments or to promote health and healing OR A drug or preparation made from a plant or plants and used for any of such purposes

M EDICAL TERMINOLOGIES
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Abortifacient- Inducing abortion
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Adjuvant- aiding the action of a medicinal agent
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Analgesic- relieve pain
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Anesthetic- induces loss of sensation or consciousness due to the depression of nerve function

M EDICAL TERMINOLOGIES
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Antifungal- destroying or inhibiting the growth of fungus
Antihemorrhagic- controlling hemorrhaging or bleeding.
Aperient- a very mild laxative
Aperitive- stimulating the appetite for food
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Aphrodisiac- substance increasing the capacity for sexual arousal
Astringent- substance is a chemical compound that tends to shrink or constrict body tissues , usually locally after topical medicinal application

M EDICAL TERMINOLOGIES
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Antipruritic- preventing or relieving itching
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Antipyretic- agent that reduces fever
Antispasmodic- calming nervous and muscular spasms or convulsions
Antitussive- controlling or preventing cough