Evaluation of crude drugs is necessary to identify them, determine quality and purity, and detect adulteration. Microscopic evaluation specifically can identify organized drugs by histological characters using reagents or stains. It involves examining parameters like stomatal number and index, vein-islet and veinlet termination numbers, palisade ratios, and presence of structures like starch grains or calcium oxalate crystals through techniques like the Lycopodium spore method. This allows determination of purity, detection of adulterants, and differentiation of similar drugs.

1. Evaluation of Crude drug
PRESENTED BY:
MR. PRITAM VIJAY JUVATKAR
ASSISTANT PROFESSOR
pvjuvatkar@rediffmail.com, +91 9987779536
KONKAN GYANPEETH RAHUL DHARKAR COLLEGE OF PHARMACY AND
RESEARCH INSTITUTE, KARJAT
UNIVERSITY OF MUMBAI

2. Evaluation of Crude
drug
 Evaluation of a drug means confirmation of
its identity and determination of its quality
and purity and detection of nature of
adulteration,
The evaluation of a crude drug is necessary
because of three main reasons
 Biochemical variation in the drug,
 Deterioration due to treatment and storage,
 Substitution and adulteration, as a result of
carelessness, ignorance or fraud.

3. Types of Evaluation of Crude drug
 Morphological or organoleptic evaluation
 Chemical evaluation
 Microscopical evaluation
 Microscopic evaluation
 Chromatographic techniques
 Spectrophotometric methods
 Biological evaluation
 Biotechnological method
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Pritam Vijay Juvatkar 9987779536

4. Microscopic evaluation

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Microscopical evaluation
 It can be used to identify the organized drugs by their known histological characters.
 It is mostly used for qualitative evaluation of organized crude drugs in entire and powdered
forms.
 For the effective results, various reagents or stains can be used to distinguish cellular structure.
.
 A drop of phloroglucinol and concentrated hydrochloric acid
give red stain with lignin
 Mucilage is stained pink with rhuthenium red and also, when
treated with corallin soda and few drops of sodium carbonate
solution, cellulose swells and dissolves in cuoxam, while N/50
iodine solution stains starch and hemicellulose blue.
 Eg. Lignified trichomes in nux vomica, warty trichomes of
senna, wavy medullary rays of cascara bark, glandular
trichomes of mint etc.

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Microscopical evaluation
 The powdered cloves do not contain sclereids or calcium
oxalate crystals, but both of them are present in powdered
clove stalks.
 The techniques like microscopic linear measurements,
determination of leaf constants and quantitative
microscopic are also used in this evaluation.
 Linear measurements include size of starch grains, length
and width of fibres, trichomes,etc

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Microscopical evaluation
 Determination of leaf constants include
 Stomatal Number,
 Stomatal Index,
 Vein Islet,
 Veinlet Termination Number And
 Palisade Ratios.
.

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Microscopical evaluation : Parameter 1
 Stomatal number
It is average number of stomata per sq. mm of epidermis of the leaf.
 Stomatal index:
 It is the percentage which the numbers of stomata form to the total number of
epidermal cells, each stoma being counted as one cell.
 Stomatal index can be calculated by using the following formula:
• Stomatal index(S.I.)= S/(E+S)×100
• Where, S=Number of stomata per unit area
• E= Number of epidermal cells in the same unit area.
 Timmerman (1927) and Rowson (1943)
 Stomatal index of Alexandrian senna is 10-15,whereas that of Indian senna is
14-20

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Microscopical evaluation : Parameter 2
 Vein-islet number—
• The number of vein islet per sq.mm of the leaf surface midway between
the midrib and the margin.
• Levin in 1929
 Veinlet termination number:
• The number of veinlet termination per sq. mm of the leaf surface midway
between midrib and margin.
• Hall and Melville in 1951
• Eg. Vein-islet number of Alexandrian senna is 25-29.5, where Indian senna
is 19.5-22.5.

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Microscopical evaluation : Parameter 3
 Palisade ratio
• The average number of palisade cells beneath each epidermal cell.
• Palisade ratio can be determined with the powdered drug.
• Zorning and Weiss(1925) in their studies on compositae.

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Microscopical evaluation : Parameter 4
 Lycopodium spore method:
• This method is use to identify the crude drugs
• This method is also useful to detect the adulteration present in the
crude drugs containing starch grains.
• Examples: Adulterated drug containing starch can be determined
by counting the number of starch grains per mg and calculating
the amount from the known number of starch grains per mg of the
pure starch.
• The percentage purity of an authentic powdered ginger is
calculated using the following equation:

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Microscopical evaluation : Parameter 4
 Lycopodium spore method:
• The percentage purity of an authentic powdered ginger is
calculated using the following equation:
Where,
• N = Number of characteristic structures (starch grain) in
25 fields.
• W = Weight in mg of lycopodium taken.
• S = Number of lycopodium spores in the same 25 fields.
• M = Weight in mg of the sample, calculated on the basis
of sample dried at 105°C.
• P = 2,86,000 in case of ginger starch grains powder.
Significance:
• Determination of
foreign organic matter.
• Determination of
percentage purity of
drugs.
• Detection of adulterant

13. Thank You
PRESENTED BY:
MR. PRITAM VIJAY JUVATKAR
ASSISTANT PROFESSOR
pvjuvatkar@rediffmail.com, +91 9987779536
KONKAN GYANPEETH RAHUL DHARKAR COLLEGE OF PHARMACY AND
RESEARCH INSTITUTE, KARJAT
UNIVERSITY OF MUMBAI

14. Disclosure
This Presentation is meant for Study Notes for B.Pharm Students only. Please
do not take as a reference for treatment for an ailments or other usage
PRESENTED BY:
MR. PRITAM VIJAY JUVATKAR
ASSISTANT PROFESSOR
pvjuvatkar@rediffmail.com, +91 9987779536
KONKAN GYANPEETH RAHUL DHARKAR COLLEGE OF PHARMACY AND RESEARCH INSTITUTE, KARJAT
UNIVERSITY OF MUMBAI