3. STANADARDIZATION
Standardization/evaluation of a drug means confirmation of its
Identity (authentic biological source)
Quality (intrinsic value of drug)
Purity (absence of organic/ inorganic foreign matter)
and detection of nature of adulteration.
Standardization of plant drug is necessary because of following reasons :
Biochemical variation
Deterioration during storage or treatment
Substitution or adulteration
The different techniques involved in standardization are as follow:
Morphological evaluation
Microscopic evaluation
Physical evaluation
Chemical evaluation
Biological evaluation
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5. ORGANOLEPTIC PROPERTIES OF PLANT DRUG
These refers to drug evaluation by means of our organs of sense and
include gross morphology and other sensory characters like odour,
colour, taste and texture.
GROSS MORPHOLOGY
It includes visual appearance to the naked eye.
It depends largely on the part of the plant from which drug is obtained.
All organized drugs belongs to the one of the following morphological
groups:
Barks
Underground structures
Leaves
Flowers
Fruits
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6. Barks
All the tissues in a woody stem outside the inter fascicular cambium
constitute bark drugs. Barks are collected by stripping from the
trunks or branches of tree. e.g. Cinnamon , Cinchona, Quillia,
Asoka, Kurchi bark etc.
Curved Recurved
Flat
Compound quillDouble quill ChanneledQuill
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7. Underground structures
Used by plants as food storage organ. Often available as swollen, sliced &
cut into small pieces or scrapped to remove the dark cork . These
generally include roots, rhizomes, stolons, corms, tubers and bulb.
Roots: No buds, nodes and internodes, scale leaves or leaf scars and
have central core of woody xylem tissue. Root is covered by root caps.
e.g. Podophyllum, Liquarice, Jatamnsi, Rauwolfia.
•Rhizomes and stolons: Underground horizontal, storage stems which
have scale leaves, nodes and internodes, buds and scars , central pith. e.g.
Ginger, Turmeric, Dioscoria
Stolon Rhizome 7
8. Tubers: Swollen underground storage as well as propagation structures
having ‘eyes’ from vegetative buds, adventitious roots (roots arising from
other part of plant) are absent. e.g. Potato, Jalap, Aconite, Dioscoria.
Bulb: Specialized underground shoot act as an organ of propagation and
perennation (to live over from one growing season to another). It has
fleshy scales , buds. e.g. Garlic, Onion, Squill .
Corm: Stout and grow vertical in direction, having buds, adventitious
roots at the base. e.g. Saffron and Colchicum.
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9. Leaf
Leaves are appendages to the stem which generally are in flattened form,
thin, have chlorophyll and veins.
They possess neither nodes nor internodes and branches arises in their
axil.
The word leaf include leaf, compounded leaf and leaflets.
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10. Flower
These are reproductive organs of a plant and consist of four basic parts:
Calyx : It is the outermost whorl of flower and is generally green in
colour. The individual no. of calyx is called sepal.
Corolla: It is the second whorl of flower and is either white or bright
colored. Each member of the corolla is known as petals.
Androecium: It is the third circle of flower and constitute the male
part. The individual component is called as stamen & each stamen
consists of filament, anther and connective.
Gynoecium: This is the fourth circle of the flower and constitute the
female part. Each component is known as carpel or pistil and is made
up of stigma, style and ovary.
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11. Fruits
The ovary develops further to form protective covering over the seeds,
which is known as the fruit, in botany this particular coating is called as
pericarp.
The pericarp consists of three types:
. Epicarp
. Mesocarp
. Endocarp
Fruits
a. Simple fruits b. Compound fruits
Long pepper, Pineapple
Mulberry
Dry fruits
Dehiscent fruits
1.Legume:Gram, pea ,Senna
2. Capsule: Cotton, Poppy
3. Follicle: Anise, Calotropis
4. Siliqua: Radish, mustard
Indehiscent fruits
1.Achene: Cannabis, Sunflower,
Rose
2.Caryopsis: Rice, Wheat, Maize,
3. Nut: Cashew nut, Areca nut
4.Samara:Dioscorea, Shorea
5.Schizocarps:Acacia, Peanut,
Coriander
Fleshy fruits
(Succulant fruit)
1.Drupe:Coconut, Mnago, Plume,
Olive
2.Berry:Capsicum,Bael,Colocynth,
3. Pome: Apple,Pear
4. Hesperidium:Orange, Lemon, grape
5.Balausta: Pomegranate
c. Aggregate fruits
Raspberry, star anise
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12. Seeds
The seed is a fertilized ovule. Seeds are characterized by the presence of three
parts known as embryo, endosperm (nutritive tissue) and seed coat. On this basis
seeds may be:
Endospermic (Albuminous): Part of endosperm remain until the germination
of seed and is partly absorbed by the embryo. It shows distinct presence of the
endosperm. e.g. Colchicum, Isapgol, Linseed, Nuxvomica
Nonendospermic: During development, endosperm is fully absorbed by embryo
and endosperm is not represented. e.g. Sunflower, Tamarind, Cotton, Soybean
Perispermic: Nucleus develop to form a big storage tissue and seeds are found
to contain embryo, endosperm, perisperm and seed coat. e.g. Pepper, Cardamom,
Nutmeg.
Seeds are characterized by the following structures:
Hilum: The point of attachment of seed to stalk.
Microphyle: It is the minute opening of the tubular structure, for the
germination of seeds.
Raphe: Longitudinal marking of adherent stalk of anatropous ovule.
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14. Microscopic evaluation allows more detailed examination of a drug and
it can be used to identify the organised drugs by their known
histological characters. It is mostly used for qualitative evaluation of
organised crude drugs in entire and powdered forms.
In this method drug is examined under microscope. This can be
performed by powdering, cutting a thin section (LS/TS) or preparing a
macerate of crude drug. The characteristics of cell wall, fiber,
trichomes, sclereids, vessels, stomata etc. are examined in details.
Microscopic evaluation involves :
• Determination of Leaf constants
• TS/LS of drug
• Powder Microscopy involving trichome, starch grains, calcium oxalate
crystal etc.
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15. Leaf constants
Palisade ratio is defined as average number of palisade cells beneath
each epidermal cell can be determined with powdered drugs.
Vein islet number is defined as the number of vein islets per sqaure.mm
of the leaf surface midway between the midrib and margin.
Vein termination number is defined as the no. of vein terminations per
sq. mm of the leaf surface midway between midrib and margin.
Stomatal number is average no. of stomata per sq. mm of epidermis of
the leaf.
Stomatal index is the percentage which the number of stomata form to
the total number of epidermal cells; each stomata being counted as one
cell. It is calculated using the following equation.
S.I. = S/ E+S x 100
S.I: Stomatal index
S: No. of stomata per unit area
E: No. of epidermal cells in the same unit area
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16. Stomata
A stoma is a minute opening with a central pore and two kidney shaped
similar cells containing chloroplasts known as guard cells and varying
number of subsidiary cells covering the guard cells.
Types of stomata:
Anomocytic (Ranunculaceous or irregular celled stomata):
Digitalis, Lobelia
Anisocytic (Cruciferous or unequal celled stomata):
Belladonna, Datura, Stramonium
Diacytic (Cariophyllaceous or cross celled stomata):
Peppermint and Vasaka
Paracytic (Rubiaceous or parallel celled stomata):
Coca and Senna
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17. Powder microscopy
Trichomes are tubular elongated or glandular outgrowth of the
epidermal cell. Trichomes are also called as plant hairs. Trichomes
consists of 2 parts viz., root (in the epidermis) and body (outside of the
epidermis).
Starch Grains: Polysaccharides granules of plant origin are known as
starches. Following are the important pharmaceutical starches
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18. Calcium Oxalate crystals: They may be present in all parts of plants.
They provide protection to plant against animals and birds. They have
great diagnostic value and help in detection of adulterants.
Fibers: Usually develop in bundles, thick walled, narrow lumen and
pointed ends. They are usually lignified, but may also contain cellulose.
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20. PHYSICAL EVALUATION
Physical evaluation is the method used to find out or determine the
physical standards for a drug. These are rarely constant for crude drug, but
may be helpful in evaluation. It is very essential for determination of
quality and purity of drug. Physical evaluation involves following
parameters:
Foreign matter: It may be defined as the part other than required part and
any other organic material which may include animal excreta, insects or
moulds. Such contaminations may lead to certain toxicities which are not
attributed to the drug.
Moisture content: Presence of moisture content in a drug can lead to
deterioration due to activation of certain enzymes or growth of microbes.
Extractive values obtained for a crude drug in a particular solvent are
indicative of their chemical constituents. Alcohol soluble extractives give
an indication of the amount of resins, tannins and such other constituents
if present in drug. Water soluble extractives are applied to drugs which
contain water soluble constituents like tannins, sugars, plant acids,
mucilage, glycosides etc.
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21. Ash value is an important parameter for determining authenticity and purity
of drugs and also these values are important quantitative standards. Total ash
is designed to measure the physiological (plant tissue) and non-
physiological (sand and soil) ash. Acid insoluble ash is used to measure
amount of silica present, especially as sand and siliceous earth. Sulphated
ash value measures the amount of sulphates.
Refractive index: It may be defined as the ratio of velocity of light in
vaccum to velocity of light in substance/ medium. It is the ratio of sine of
angle of incidence to the sine of angle of refraction. It is measured by
refractometer. Used for evaluation of volatile oils and fixed oils.
Optical rotation: Many substance of biological origin can rotate the plane
of polarized light either to right or to left side. Such components are said to
be optically active and are designated as dextrorotatory and leavo rotatory.
The extent of rotation is expressed in degree ±. It can be measured by using
polarimeter.
Swelling index: It is observed to determine significant amount of mucilage
present in powdered drug.
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23. PHYTO-CHEMICAL EVALUATION
Crude drug contain primary and secondary metabolites. Generally
secondary metabolites are physiologically active. Phytochemical
screening is performed for chemical evaluation of crude drugs which
give a clear cut picture of chemical constituents present in the plant.
Chemical evaluation of crude drugs is more appropriate because this
identifies as well as estimates the phyto-constituents present in a drug.
The purity of crude drug is ascertained by quantitative estimation active
chemical constituents present in them.
Preparation of extracts
The air dried plant is successively extracted with various solvents in
increasing polarity including like petroleum ether, chloroform etc. by
soxhlation. Each time before extracting with next solvent, the powdered
material is dried in hot air oven below 50ºC. Each extract is
concentrated by distilling off the solvent and then evaporated to dryness
on water bath. The percentage yields of different extracts are calculated
in terms of air dried weight of plant material
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24. Qualitative analysis /Phytochemical screening: It is carried out on
the extracts to determine the presence of alkaloids, carbohydrates,
glycoside, phenolic compounds, flavonoids, protein and amino acids,
saponins, sterols, fats and fixed oils, organic acids etc.
Confirmation by Chromatographic techniques: The presence of
different phytoconstituents can be confirmed by using different
chromatographic techniques like TLC, HPTLC, HPLC, GLC and other
spectroscopic techniques etc.
Quantitative analysis
Quantitative estimations of different phytoconstituents is done
thereafter like total alkaloidal content, total phenolic, flavonoid content
etc. by using different methods.
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26. BIOLOGICAL EVALUATION
When the estimation of potency of crude drug or its preparation is done
by means of its effect on living organisms like bacteria, fungal growth or
animal tissue or entire animal, it is known as bio-assay. Some drugs
have specific biological and pharmacological activities which are
utilized for their evaluation.
In standardization of herbal drugs, assessment of biological efficacy is
found to be most assuming method. In all these methods, requirements
are a suitable animal model for testing and control methodology for
experiment and assessment of results.
Experiments can be done both on intact or isolated organs of living
animals. With the help of Bioassay testing strength of drug and its
preparation can also be determined. Biological assay methods are
mainly of 3 types: toxic, symptomatic and tissue methods. In toxic and
symptomatic techniques, the animals are used, whereas in tissue method
isolated animal organ or tissue is used.
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27. Various biological activities like hepatoprotective, hypoglycemic,
analgesic, anti-inflammatory, antipyretic and neuropharmacological
activities can be evaluated.
Different animals are used for evaluation of different types of
biological activities of plants which are given as follow:
• Mice : Rabies, Diphtheria vaccines
• Chickens: Oxytocin injection
• Pigeons: Cardiotonic activity of Digitalis
• Rabbits: Muscle relaxing activity of Curare alkaloids
In this way the biological activities of various drugs can be checked
by using different animals and different models. Finally drugs are
tested on human beings before a new drug is introduced in the
market.
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