Content
Evaluation of Natural Products
Course Code: BP405T
Course Title: Pharmacognosy and Phytochemistry I
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Content
Evaluation of Natural Products
✓ Morphological evaluation
✓ Microscopical evaluation
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Lecture No 1
Evaluation of Natural Products
• At the end of this lecture, students will be able to
✓Discuss the importance of evaluation of crude drugs
✓Discuss the various parameters involved in Morphological
and Microscopical evaluation
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Evaluation of Natural Products
Evaluation
✓ Confirmation of identity,
✓ Determination of quality and purity
✓ Detection of adulterants
Need
✓ Biochemical variation in the drug
✓ Detoriation due to treatment and storage
✓ Substitution and adulteration – carelessness, ignorance
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Evaluation of Natural Products
✓ Morphological evaluation
✓ Microscopical evaluation
✓ Physical evaluation
✓ Chemical evaluation
✓ Spectroscopic al evaluation
✓ Biological evaluation
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Evaluation of Natural Products
Morphological or organoleptic evaluation
Evaluation of Natural Products
Morphological or Organoleptic Evaluation
Qualitative evaluation based on morphology and sensory profile of drugs
✓ Colour
✓ Odour
✓ Taste
✓ Size
✓ Shape
✓ Special features like touch, texture, fracture
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Evaluation of Natural Products
Morphological Evaluation
Examples: Shapes
✓ Ovoid tears – Acacia
✓ Ribbon shape – Tragacanth
✓ Disc shape- Nuxvomica seed
✓ Conical – Aconite
✓ Quills – Barks
✓ Wavy – Rauwolfia
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Evaluation of Natural Products
Colour:
✓ Brown colour- Cinnamon
Odour:
✓ Aromatic odour – Umbelliferous fruits
Taste:
✓ Bitter Taste – alkaloids containing drugs
✓ Sweet taste – Liquorice
✓ Pungent taste- Capsicum, Ginger
✓ Astringent taste- asafoetida, black pepper, nutmeg, caraway, cumin
✓ Acrid taste – Castor oil, Chaulmoogra oil
✓ Bland taste – Arachis oil, sesame oil,
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Evaluation of Natural Products
✓ Fracture
Short – Cinchona
Splintery – Cinnamon bark
Short and granular – Cascara bark
Laminated – Quillaia bark
✓ Over drying- brittle- morphological evaluation – difficult task
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Evaluation of Natural Products
Microscopical Evaluation
✓ Evaluation of crude drugs – microscopical / histological characters
✓ Qualitative evaluation of organized drugs in whole and powder form
✓ Microscopical evaluation can be performed by
Sectioning of the drug – T.s
Histochemical test
Powder microscopy
Quantitative microscopy – Leaf constants
Lycopodium spore method
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Evaluation of Natural Products
Microscopical Evaluation
• Histological studies- thin sections
Characteristics-
✓ Cell wall
✓ Cell contents – Starch grains, Crystals
✓ Trichomes
✓ Fibres ✓ Lignified trichome
✓ Vessels ✓ Warty trichome
✓ Wavy medullary rays of cascara bark
✓ Glandular trichome of mint
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Evaluation of Natural Products
Microscopical Evaluation
• Histochemical test
✓ Lignin – Phloroglucinol and Conc. HCl
✓ Mucilage – Ruthenium red
✓ Starch – N/50 iodine
✓ Phenolic compounds – Ferric chloride
✓ Alkaloids – Dragendroff’s reagent
✓ V. oil – Sudan red III
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Evaluation of Natural Products
Microscopical Evaluation
Powder microscopy
Helps in the identification of crude drugs and detecting adulterants
1. Identification – senna – Paracytic stomata, unicelluar covering
trichomes
2. Detection of adulterants – Clove powder
✓ Powdered clove stalk- sclereids ,prism calcium oxalate crystals
✓ Mother clove – Powdered clove fruits – starch
✓ Powdered clove flower bud: No starch
No sclereids
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Cluster crystals 14
Evaluation of Natural Products
Microscopical Evaluation
Powder microscopy – Digitalis
1. Comfrey leaves – Symphytum officinale – Hook at the top
2. Primrose leaves – Primula vulgaris – 6-12 celled
3. Mullein leaves – Verbascum thapsus – Cadelabra trichomes
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Evaluation of Natural Products
Microscopical Evaluation
Microscopical linear measurements/quantitative microscopy
• dimension of the cell (fiber, stone cell, trichome), cell contents (starch
grains), pollen grains of crude drug both in entire form or powder form
1. Micrometry Eye piece micrometer
Stage micrometer
2. Camera lucida
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Evaluation of Natural Products
• Calibrate eye piece micrometer – calibration factor
• 0 – 0 coincidence
• Next consecutive three coincidence – noted down
• Calibration factor
Eye piece micrometer division Stage micrometer division
3 4
11 15
14 19
• 3 division of eye piece micrometer = 4 divisions of stage micrometer
• 1 division stage = 0.01 mm = 10 µ
• 4 divisions = 40 µ
• 1 division of eye piece micrometer = 40/3 = 13.3
• Average calibration factor = 13
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Evaluation of Natural Products
Camera lucida
1. Swift Ives camera lucida
2. Abbe’s camera lucida with sliding mirror
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Evaluation of Natural Products
Microscopical Evaluation
Leaf constants
✓ Stomatal number
✓ Stomatal index
✓ Palisade ratio
✓ Vein islet number
✓ Vein termination number
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Drug Stomatal number Stomatal index
Atropa Upper – 7-10 D. purpurea Upper – 1.3 to 3.5
belladona Lower – 77-115 Lower – 17.9 – 19.5
Cassia Upper – 220-260 D. lanata Upper – 13.9 – 14.7
angustifolia
Lower – 240-265 Lower – 14.9 – 17.6
Drug Vein termination Drug Palisade ratio
number Atropa belladona 5-70
Cassia acutifolia 32.7 – 40.2 Cassia Upper -5.5-10
Cassia angustifolia 25.9 – 32.8 angustifolia Lower : 4-7.4
Drug Vein islet number
D. purpurea 2.5 – 3
D. lanata 2- 8
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Evaluation of Natural Products
Microscopical Evaluation
Stomata
– Stomatal pore
– Guard cells
– Subsidiary cells
Types of Stomata Dicot
– Moss – Paracytic
– Gymospermous – Diacytic
– Gramineous – Anamocytic
– Dicot – Anisocytic
Evaluation of Natural Products
Microscopical Evaluation
Paracytic / Parallel celled / Rubiaceous
Diacytic / Cross celled (Diagnol) / Caryophyllaceous
Evaluation of Natural Products
Microscopical Evaluation
Anamocytic / Irregular celled (anamos=many) / Ranunculaceous
Anisocytic / Unequal celled / cruciferous
Evaluation of Natural Products
Microscopical Evaluation – Trichomes
• Elongated tubular outgrowth of epidermal cell
• Plant hairs
• Any part – leaf, seed, fruit etc/ absent in roots
• Function- Protective, secertion of V.oil (Mentha spp), absorption or
secretion of water (Piper betel)
Evaluation of Natural Products
Microscopical Evaluation – Trichomes
1. Covering / Non glandular / Clothing
A. Unicellular B. Multicellular
Un branched Branched
1. Uniseriate 1. Stellate
2. Biseriate 2. Peltate
3. Multiseriate 3. Candelabra
4. T- shaped
2. Glandular
3. Hydathodes / Special type
Evaluation of Natural Products
Microscopical Evaluation – Trichomes
Unicellular covering trichomes
Lignified – Nuxvomica
Short, sharp, curved – Cannabis
Large, conical, shrunken – Lobelia
Short, conical, unicellular – Tea
Strongly waved, thick walled – Yerba santa
Multicellular covering trichomes
Uniseriate
Bi cellular, conical – Datura
Three celled – Stramonium
Three to four celled – Digitalis
Four to five celled – Belladona
Biseriate- Calendula officinalis
Multiseriate – Male fern
Evaluation of Natural Products
Microscopical Evaluation – Trichomes
Multicellular BRANCHED trichomes
Stellate – Hammamelis
Peltate – Humulus
Candelabra – Verbascum thapsus
T shaped – Pyrethrum
Evaluation of Natural Products
Microscopical Evaluation – Trichomes
GLANDULAR TRICHOMES
Unicellular: Stalk absent – betel, vasaka
Multicellular:
Unicellular head/unicellular stalk – Digitalis purpurea
Unicellular head / uniseriate multicellular stalk – Digitalis thapsi, Belladona
Multicellular head / multicellular biseritae stalk – Sunflower, compositae
Unicellular stalk / biseriate head – Digitalis purpurea
Short stalk / rosette head – Mentha
Multicellular multiseriate cylindrical stalk / rosette secretory head – Cannabis
Multicellular uniseritae stalk / Multicellular multiseriate head – Indian hemp,
Evaluation of Natural Products
Microscopical Evaluation – Mineral Crystals
➢ Crystalline deposits
➢ Present in any part of the plant
➢ Insoluble in water
➢ Calcium oxalate, calcium carbonate and silica
➢ Occur in various forms like prisms, acicular, raphides, clusters,
rosettes, druses etc
➢ Have – diagnostic value
➢ Significance – identification and detection of adulterants
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Evaluation of Natural Products
Microscopical Evaluation – Mineral Crystals
• Identification
• Prisms: Quillaia, Senna, Liquorice, Wild Cherry
• Acicular/Raphides: Cinnamon, Squill, Gentian, Andrographis
• Rosettes or clusters: Cascara, Clove, Arjuna, Eucalytpus
• Microsphenoidal or sandy: Cinchona, tobacco, henbane
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Evaluation of Natural Products
Microscopical Evaluation – Mineral Crystals
Examples : Detection of adulterants and substitutes
Clove Stalk – prism type, flower bud – no crystal
Solanaceous leaves Type of crystals
Belladonna Microspenoidal
Hyosyamus Prism
Stramonium Cluster
➢ Absent – digitalis, nutmeg, linseed, colchicum
Evaluation of Natural Products
Microscopical Evaluation
Lycopodium spore method
✓ Powdered drugs
✓ When chemical and other methods fail
✓ Inexpensive method- official
✓ Lycopodium spores-
❖ Characteristic in shape,
❖ Uniform in size 25 micron
❖ 94,000 spores per mg of powdered lycopodium
Evaluation of Natural Products
Microscopical Evaluation
Lycopodium spore method
✓ Well defined particles that can be counted (starch, pollen grains)
✓ Single layered cells/ tissues and the area can be traced
✓ Objects with uniform thickness- length of which can be measured
[(NxWx94,000)/(SxMxP)]*100
N=No. f characteristic structures in 25 fields
W= Wt in mg of lycopodium taken
S = No. of lycopodium spores in the same 25 fields
M= wt of sample in mg
P = 2,86,000 in case of ginger
Evaluation of Natural Products
Microscopical Evaluation
Lycopodium spore method
✓ 100 mg of ginger powder and 50 mg of lycopodium powder
✓ Suspending fluid – Glycerine, tragacanth gum and water (2:1:2)
✓ Dilute till about 15-20 spores are observed in a single field
✓ Add iodine, count the number of spores and starch grains in 25
different fields
✓ Determine the percentage purity of ginger
✓ % purity = (NxWx94,000×100)/(SMP)
Summary
✓ Evaluation is a process of confirmation of identity, determination of
quality and purity, and detection of nature of adulterants
✓ Morphological evaluation includes the application of various
organoleptic characters in evaluation the crude drugs
✓ Microscopical evaluation includes the application histological
studies, linear measurements etc
✓ Microscopical evaluation can be applied to crude drugs as such, and
also in powdered form
Thank You
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