intoduction to pharmacognosy

1. EVALUATION
OF CRUDE DRUG
PRESENTED BY – MOHD EHSAN
M.Pharm (Ay)
Institute of Medical Sciences, RGSC, BHU

2. Definition
Confirmation of its identity and determination
of its quality and purity

3. Methods
Morphological
Microscopical
Chemical
Physical
Biological or pharmacological

4. Morphological method of drug Evaluation
Also called as organoleptic method Crude drugs evaluated with the help of;
• Color
• Odor
• Taste
• Size
• Shape
• Any extra character or features of crude drugs
E.g. liquorice - sweet taste, Aloe- blackish brown color, Gum Acacia-
Gummy taste

5. Microscopical method of Drug Evaluation
Drugs evaluated with help of microscope
Types of microscope
• Simple,
• Compound or student
• Electronic, – Electric, – Projection.
The unique arrangement of cells and tissues after taking the transverse
section (T.S.) observed under microscope, which is helpful for drug
evaluation
Cont…

6. Microscopical method of Drug Evaluation
Sometime the TS treated with various chemical (called staining reagent
eg. Phloroglucinol + Conc HCl) such test called microchemical tests
The microscopical method of drug evaluation helpful for identification
of organized crude drugs.
The leaf, bark, stem, root used as crude drugs were identified with help
of this method.

7. Leaf Constants
• Stomatal number
• Stomatal index
• Vein-islet number
• Palisade Ratio

8. Leaf constants
• Stomatal number : The average number of stomata
per square mm.
• Stomatal index : It is the percentage of number
of stomata (S) in a certain area to the sum of total
number of epidermal cells (E) and stomata together in same unit area.
Stomatal index = S x 100/E + S

9. Leaf constants
• Vein-islet number – It is defined as no. of vein islet per square mm of
leaf surface midway b/w midrib and margin.

10. Leaf constants
• Palisade Ratio
Palisade ratio were used for identification of crude drugs.
It is the average no. of palisade cells beneath each
epidermal cells.

11. Chemical method of drug Evaluation
• The crude drugs evaluated by various chemical available in the
laboratory.
• This method is qualitative method of drug evaluation
• The crude drugs consists phytoconstituents which gives color reaction
with laboratory chemicals
Example-
 Carbohydrates + Molish reagent → Violet color
 Tannins + Ferric chloride solution → Blue-Black ppt
 Alkaloids + Dragendroff’s reagent → Orange ppt

12. Chemical method of drug Evaluation
Apart from qualitative chemical tests quantitative chemical tests were
also perform;
• Acid value
• Iodine value
• Phenol value – Saphonification value
• Alkaloidal content etc.
Cont…

13. PHYSICAL METHODS
STANDARDIZATION OF HERBAL DRUGS
• Viscosity
• Melting point
• Solubility
• Moisture content and volatile matter
• Specific gravity
• Density
• Optical rotation
• Refractive index

14. PHYSICAL METHODS
STANDARDIZATION OF HERBAL DRUGS
• Particle size determination
• Bulk density
• Bitterness value
• Hemolytic activity
• Swelling index
• Foaming index
• Ash value
• Astringency
• Organoleptic testing
• Determination of Ash value
• pH estimation
• Estimation of foreign materials

15. Biological or Pharmacological method of
drug Evaluation
In this method the potency estimation carried out for crude drug on
any living organism.
The living organism may be mice, rat, guinea pig, cat, dog, monkey, horse, isolated tissue,
bacteria, viruses, fungi.
Bio-assay-to study the effect of drugs on living organism.
There are 3 types-
– Toxic bio-assay
– Tissue method bio-assay
– Symptomatic bio-assay
E.g.-
– Potency of antibiotic evaluated on Microorganism
– Analgesic activity evaluated on mice