Evaluation of Natural Products, Discuss the various parameters involved in Morphological, Microscopical, Chemical, Physical, Spectroscopic and Biological evaluation

Evaluation of Natural Products

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Content

Evaluation of Natural Products

Morphological
evaluation

Microscopical
evaluation

Chemical
evaluation

Physical
evaluation

Spectroscopic
methods

Biological
methods

Objective

• 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, Microscopical, Chemical, Physical,
Spectroscopic and Biological evaluation

Evaluation of Natural Products

Evaluation

Confirmation of
identity,

Determination
of quality and purity

Detection of
adulterants

Need of Evaluation

Biochemical
variation in the drug

Detoriation due
to treatment and storage

Substitution
and adulteration – carelessness, ignorance

Type

 of Evaluation

Morphological
evaluation

Microscopical
evaluation

Physical
evaluation

Chemical
evaluation

Spectroscopical
evaluation

Biological
evaluation

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

Examples: Shapes

Ovoid tears –
Acacia

Ribbon shape –
Tragacanth

Disc shape-
Nuxvomica seed

Conical –
Aconite

Quills – Barks

Wavy – Rauwolfia

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,

Fracture

Short –
Cinchona

Splintery –
Cinnamon bark

Short and
granular – Cascara bark

Laminated –
Quillaia bark

Over drying-
brittle- morphological evaluation – difficult task

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

Histological
studies- thin sections

Characteristics-

Cell wall

Cell contents –
Starch grains, Crystals

Trichomes

Fibres

Vessels

Lignified
trichome

Warty trichome

Wavy medullary
rays of cascara bark

Glandular
trichome of mint

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

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 cr

Mother clove –
Powdered clove fruits – starch

Powdered clove
flower bud:  No starch

                            
                    No
sclereids

                                                 Cluster crystals

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

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              

• 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

Camera
lucida

1. Swift Ives camera lucida

2. Abbe’s camera lucida with sliding mirror

Leaf
constants

• Stomatal number

• Stomatal index

• Palisade ratio

• Vein islet number

• Vein termination number

Drug

Stomatal
number

 

Stomatal
index

Atropa belladona

 

Upper – 7-10                   
Lower – 77-115                                                         

D. purpurea                   

Upper – 1.3 to 3.5

Lower – 17.9 – 19.5

Cassia angustifolia

Upper – 220-260             
Lower – 240-265                                                      

D. lanata                        

Upper – 13.9 – 14.7

Lower – 14.9 – 17.6

                

Drug

Vein
termination number

Cassia acutifolia                       

32.7 – 40.2

Cassia angustifolia                   

25.9 – 32.8

Drug

Palisade
ratio

Atropa belladona                    

5-70

Cassia angustifolia

Upper: 5.5-10

Lower: 4-7.4

            

Drug

Vein
islet number

D. purpurea                                   

2.5 – 3

D. lanata                                          

2- 8

                           

Stomata

– Stomatal pore

– Guard cells

– Subsidiary cells

Types of Stomata

– Moss

– Gymospermous

– Gramineous

– Dicot

 Dicot

  Paracytic

  Diacytic

  Anamocytic

  Anisocytic

• Paracytic / Parallel celled / Rubiaceous

• Diacytic / Cross celled (Diagnol) / Caryophyllaceous

• Anamocytic / Irregular celled (anamos=many) /
Ranunculaceous

• Anisocytic / Unequal celled / cruciferous

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)

1.   Covering / Non
glandular / Clothing

A.  Unicellular                   

B. Multicellular

Un branched

• Uniseriate

• Biseriate

• Multiseriate

Branched

• Stellate

• Peltate

• Candelabra

• T- shaped

2. Glandular

3. Hydathodes / Special type

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

Multicellular
Branched trichomes

• Stellate – Hammamelis

• Peltate – Humulus

• Candelabra – Verbascum thapsus

• T shaped – Pyrethrum

     

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,

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

• 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

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

• Powdered drugs

Lycopodium
spore method

• 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

• 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

• 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)

Chemical Evaluation

• Chemical tests and assays

• Chemical test – Preliminary phytochemical screening

Preliminary
Phytochemical screening – Successive Solvent Extraction

• Air dried plant material is made into coarse powder

• Powder is extracted in Soxhlet assembly successively with
solvents in order of increasing polarity,

i.e

Pet ether/n-hexane à
Toluene/Benzene à
Chloroform à
Acetone à
Ethyl acetate à
ethanol Water (maceration)

• Each time before extracting with next solvent, the powder
is dried below 50 ⁰C

• Each extract is concentrated by distilling of solvent

• Evaporated to dryness on water bath

• Extracts with different solvents can also be prepared by
maceration

Qualitative
Chemical Examination

Test for
Carbohydrates

Dissolve small quantity of alcohol and aqueous extracts
separately in distilled water and filter. Subject the filtrate to various tests

Sl.No

Test

Observation

Inference

1.

Molisch’s test: Filtrate +
alcoholic solution of α-Naphthol + few drops of conc. sulphuric acid along
the sides of the test tube

Formation of violet ring at

the junction of the liquids

Presence of carbohydrates

2.

Barfoed test : Filtrate +
Barfoed’s reagent, heat on boiling water bath

Red ppt

Presence of carbohydrates

3.

Fehling’s test: Filtrate +
few ml of dilute HCl and heat on a water bath for 30 min+  sodium hydroxide solution, add equal
quantities of  Fehling’s A &
Fehling’s B solutions, heat on a water bath for a few min

Red-orange precipitate

Presence of carbohydrates

4.

Benedict’s test : Filtrate
+ Benedicts reagent, heat on boiling water bath for few min

Red-orange precipitate

Presence of carbohydrates

Test for
Proteins

S.
No:

Test

Observation

Inference

1.

Millon’s test: 2 ml of the
test solution + 2 ml of Millon’s reagent, heat

Formation of white precipitate that gradually turns red

Presence of proteins

2.

Biuret test: Test solution
+ few drops of 0.7% copper sulphate solution + Sodium hydroxide

Purplish violet colour

Presence of proteins

3.

Ninhydrin test : Test
solution + few drops of ninhydrin reagent, heat

Bluish colour

Presence of proteins

Test for
Lipids

S.
No:

Test

Observation

Inference

1.

Spot test : Press a small
quantity of petroleum ether and benzene extracts separately between two
filter papers

Formation of oil stains on the filter paper

Presence of fixed oils/fats

2.

Saponification test: A
small quantity of petroleum ether or benzene extract + 0.5 N alcoholic KOH +
drop of phenolphthalein. Mixture was heated on a water bath for 1 to 2 hrs

Formation of soap or partial neutralization of alkali

Presence of fixed oils/fats

Test for
Phytosterols

Reflux petroleum ether, benzene and alcohol extracts
separately with alcoholic KOH till complete saponification takes place. Dilute
the saponified mixtures with distilled water and extract with solvent ether.

Evaporate ethereal extract to dryness and subject the residue
to Liebermann-Burchard’s test

S.
No:

Test

Observation

Inference

1.

Liebermann-Burchard’s test
Ethereal residues + few drops of acetic anhydride, boil and cool + Add 1 ml
of sulphuric acid through the sides of the test tube

Formation of brown ring at the junction of two liquids and green
colour in the upper layer

Presence of steroids and triterpenoids

Test for
Alkaloids

Stirr the small portions of solvent-free chloroform, alcohol
and aqueous extracts separately with a few drops of dilute hydrochloric acid
and filter. The filtrate was tested with various alkaloid reagents

S.
No:

Test

Observation

Inference

1.

Mayer’s test: Filtrate +
potassium mercuric iodide (Mayer’s reagent)

Cream coloured precipitate

 

Presence of alkaloids

2.

Dragendorff’s test:
Filtrate + potassium bismuth iodide (Dragendorff’s reagent)

Reddish brown precipitate

Presence of alkaloids

3.

Wagner’s test: Filtrates +
solution of iodine in potassium iodide (Wagner’s reagent)

Reddish brown precipitate

Presence of alkaloids

4.

Hager’s test : Filtrates +
saturated solution of picric acid (Hager’s reagent)

Yellow precipitate

Presence of alkaloids

Test for
Flavonoid

Dissolve small quantity of alcohol and aqueous extracts
separately in distilled water and filter. Subject the filtrate to various tests

S.
No:

Test

Observation

Inference

1.

Shinoda test: Test
solution + a few fragments of magnesium metal+con.Hcl, heat

Formation of Magenta colour

 

Presence of flavanoids

2.

Alkaline reagent test: Test
solution + few drops of sodium hydroxide solution

intense yellow colour, become less intense on addition of acid

Presence of flavanoids

3.

Lead acetate test: Test
solution + few drops of 10% lead acetate Presence of solution

Formation of Yellow precipitate

 

 

Presence of flavanoids

Test for
Tannins and Phenolic Compounds

Dissolve small quantity of alcohol and aqueous extracts
separately in distilled water and filter. Subject the filtrate to various tests

S.
No:

Test

Observation

Inference

1.

Ferric chloride test: Test
solution + few drops of 5% ferric chloride solution

Formation of a bluish-black or greenish-black colour

Presence of phenolic compounds and tannins

 

2.

Gelatin test: Test
solution + few drops of 1% gelatin solution in 10% sodium chloride

Formation of white precipitate

Presence of tannins

3.

Lead acetate test: Test
solution + few drops of 10% lead acetate solution

Formation of white precipitate

Presence of tannins

4.

Aqueous bromine test: Test
solution + few drops of aqueous bromine solution

Decolouration of bromine

Presence of tannins

Test for
Glycosides

Small quantity of alcohol and aqueous extracts were
dissolved separately in distilled water and filtered. It is then hydrolysed
with dilute hydrochloric acid for a few hrs (2 to 4 h) on a water bath and
subjected to various tests to detect the presence of different glycosides

• Cardiac glycosides

• Anthraquinone glycosides

• Saponin glycosides

Test for
Cardiac Glycosides

S.
No:

Test

Observation

Inference

1.

Legal’s test: Hydrolysates
+ sodium nitroprusside in pyridine and methanolic alkali. 

Formation of blood red colour

 

Presence of cardiac glycosides

2.

Baljet Test : Section of
digitalis + sodium picrate solution

Yellow to orange colour

Presence of cardiac glycosides

Test for
Anthraquinone Glycosides

S.
No:

Test

Observation

Inference

1.

Borntrager’s test:
Filtrate +10ml of benzene, shake. Filtered and 5 ml of 10 % ammonia solution
is added to the filtrate

Formation of pink colour in ammonical layer

Presence of anthraquinone glycosides

2.

Modified Borntrager’s test:
Filtrate + FeCl3 +10 ml of benzene, shake. Filtered and 5 ml of 10 % ammonia
solution is added to the filtrate

Formation of pink colour in ammonical layer

 

Presence of anthraquinone C-glycosides

Test for
Saponin Glycosides

S.
No:

Test

Observation

Inference

1.

Foam test: About 1 ml of
alcohol and aqueous extracts were diluted separately with distilled water to
20ml and shaken in a graduated cylinder for 15 min

Formation of froth

Presence of Saponin glycosides

2.

Hemolytic test : Aqueous
extract + Ox red blood cells

Lysis of blood cells

Presence of Saponin glycosides

 

Qualitative
chemical test- detection of adulteration

– Halphens test – Cotton seed oil

– Van urk test 
Ergot

– Vitalis morin test – Tropane alkaloid

– Murexide  test –
Purine base

Quantitative
analysis/ Chemical assays

• Lipid analysis – Acid value, Sap value etc

• Resin – sulphated ash, acid value

• Balsams – acid, saponification, ester

• Volatile oil – acetyl, ester

• Gums – methoxy

• Cineole in eucalyptus oil

• Aldehyde in lemon oil

• Carvone in caraway, dill oil

• Balsamic acid, cinnamic acid in balsam of tolu, balsam of
peru, prepared storax

Titrimetric
estimations

Total alkaloid
content

• Opium (M)

• Belladona (A)

• Ipecacuanha (E)

• Nux vomica (S)

• Cinchona (Q)

• Rauwolfia (R)

Physical Evaluation

• Identify, determine purity and quality

Viscosity

• Used to determine the purity and quality

• Constant at given temp

• Index of its chemical composition

• Liquid drugs

• Eg. Liq. Paraffin – NLT 64 Centistokes

Melting
point

• Purity

• Sharp and constant – Pure chemicals/ phytochemical

Drug

Melting
point

Colophony

75- 85

okum butter

39-42

Cocoa butter

30-33

Bees wax

62-65

Wool fat

34-44

Solubility

• Identify and Presence of adulterants- solubility studies

• Castor oil

• Colophony in light petroleum

• Alkaloidal bases

• Alkaloidal salts

• Glycosides

Optical
rotation

• Rotating plane polarized light in pure state or in
solution – optically active, Property- Optical rotation

• Right- dextro

• Left -Laevo

• 25OC –sodium lamp –source of light

Drug

Angles
of optical rotation

Caraway oil

+ 75 to + 80

Castor oil

+3.5 to + 6

Clove oil

0 to – 1.5

Honey

+ 3 to -15

Eucalyptus oil

0 to + 10

Refractive
index

Purity, constant

• Ratio of velocity of light in vacuum to its velocity in
the substance

• Varies – wavelength, temperature, pressure

Drug

RI

Arachis oil

1.4678 – 1.470

Caraway oil

1.4838 – 1.4858

Castor oil

1.4758 – 1.527

Clove oil

1.527 – 1.535

Ash Values

• Remain after incineration – inorganic salts – natural or
added

• Physiological ash – tissues itself

• Non physiological ash – extraneous materials- sand dirt
etc

– Total ash – Carbonates, oxides, phosphates, silicates,
silica

– Acid insoluble ash – HCl- adhering dirt and sand

– Water soluble ash

Drug

Total
ash

Acid
insoluble ash

Cannabis

15

5

Cardamom

6

3.5

Clove

7

0.75

Ginger

6

Extractives

• Extracting by exhausting crude drugs – indication of
approximate measures of the chemical constituents

• Various solvents used – nature of chemical compounds

• Water soluble
extractives –
tannins, sugars, plant acids, mucilage, glycosides etc

Drug

Water
soluble extractive value

Ginger

NLT 10

Linseed

NLT 15

Liquorice

NLT 20

Aloe

NLT 25

Senna leaf

NLT 30

Alcohol soluble
extractives
– Tannins, resins

• 20 – 95% alcohol used

• Dilute alcohol may also be used

Drug

Alcohol
soluble extractive value

Asafoetida

NLT 50

Ginger

NLT 4.5

Myrrh

NLT 70

Aloe

NLT 10

Moisture
content

• Active chemical content expressed on air dried basis

• Decompose due to chemical or microbial contamination

– Loss on drying

– Azeotropic distillation method

– Karl Fischer method

Drug

%
Moisture content

Aloes

NMT 10

Digitalis

NMT 5

Ergot

NMT 8

Acacia

NMT 15

Starch

NMT 15

Loss on drying

• 1050C to a constant weight

• Volatile actives – toluene distillation method

Azeotropic
distillation method

• Volatile oil content

• Hydro distillation method

Drug

Water
soluble extractive value

Caraway

NLT 2.5

Fresh lemon peel

NLT 2.5

Dill

NLT 2.5

Clove

NLT 15

Fennel

NLT 1.4

Foreign
organic matter

• Parts of organ or organs other than those mentioned in the
definition and description of drug

• Maximum limit – monographs

Spectroscopic Methods

UV- visible 

Spectroscopic 

• Based on the light absorption by the substances

• 190-380 nm UV

• 380-900 nm Visible

• Electronic transition

• Single beam: Light through monochromator- sample –
detector

• Double beam: light through sample and through blank –
ratio

• Rapid scanning spectrophotometers – Multichannel detectors

• Differential spectroscopy – Presence of extraneous
materials

• Dual wavelength spectroscopy – two monochromatic beam of
different wavelengths

– Lobeline – 249 nm

– Reserpine 268 nm

– Morphine 286 nm

– Colchicine 360 nm

– Vannilin 301 nm

Visible
range

• Morphine 442 nm

• Anthraquinone 505 nm

• Ergot alkaloids – 550 nm

• Cardio active glycosides 590 nm by keller kiliani reaction

• Cyanogenetic glycosides 630 nm by pyridine pyrazolone
reaction

Sample

• 1 N NaOH

• 1 N HCl / Nitric acid with equal volume of water

IR
Spectroscopy

• Reflected, absorbed or transmitted radiant energy in the
electromagnetic spectrum ranging from 0.8 -500 cm

• Commonly used measurement is frequency –wave number

IR range

• Near IR -12500 -4000 cm-1

• Mid IR – 4000 – 400 cm-1

• Far IR 400 – 20 cm-1

• Mid IR – commonly referred IR

• Single or double beam

• Fourier transform IR (FT-IR)- recent advancement in IR,
coupled with GC/LC

• Sensitive – drugs, polymorphic modifications, exipients,
raw materials

• Sample type- any; insoluble solids, polymers, solutions or
gases

• Identical spectra – two samples with same chemical
structure

• IR- detection of functional groups- structural elucidation

• IR – Quantitative analysis

Fluorescence
Analysis

• Absorbance and re emission – Luminescence

• Reemission during receiving only – Fluorescence

• Fluorescence in visible range

– Wild cherry bark

– Belladona leaf, root

– Gambier catechu

– Aloes

• Fluorescence in UV range

– Cinchona: luminous yellow, with light blue patches

– Calumba: Yellow, phloem and cambium – dark green
fluorescence

– Hydrastis: golden yellow

– Ergot: red

– Olive oil: deep golden yellow

• Quantitative analysis – flouorimeter/ spectrofluorimeter

Nuclear
Magnetic Resonance (NMR)

• Absorption of radio frequency radiation when the sample is
kept in magnetic field

• Absorption – interaction of radiation with magnetic moment
of nuclei in the sample and it occurs at different frequencies for nuclei with
chemically different environment within a molecule

• Important tool for elucidation, stereochemistry,
configuration

• Position of proton in a complex

• Reference standard is not required

Applications:
impurities, minor components in mixtures

• Ease, speed, specificity in analysis

NMR-MS

• Mass Spectrometry

• Electron ionization

• Subsequent fragmentation

• Determination of m/e and relative abundance of ions

Application: MW

• Alone or in combination with other techniques – effective
method of identification

• LC-MS / GC-MS

X-ray
Diffraction Method

• Capable of crystallizing in more than one crystal lattice

– Calcium oxalate, mica, sulphur etc

• At a specific temp and pressure: only one crystalline form
is thermodynamically stable

Chromatographic
Techniques

• Thin Layer Chromatography (TLC)

• High Performance Thin Layer Chromatography (HPTLC)

• High Performance liquid chromatography (HPLC)

• Gas chromatography / Gas liquid chromatography (GC / GLC)

• Column Chromatography

• Gel permeation, etc

Biological Evaluation

• Estimation of potency of drug/preparation on living
organism, fungi bacteria, tissue or entire animal – Bioassay

• Bioassay – measure of sample being tested capable of
producing same response as that of standard

• Activity represented as IU

– Digitalis: 1 IU is contained in 76 mg of Std prepn

– Vit A: 1 IU 0.344 micrograms of std preparn

– Vit D: 1 IU 0.025 micrograms of std preparn

– Heparin: 1 IU 7.7 micrograms of std preparn

Bioassays:

• Toxic – animals

• Symptomatic – animals

• Tissue – isolated organs or tissues

Biological
testing:

Hepatoprotective
activity

• CCl4, Paracetamol, Isoniazid,

• Liver enzymes

• Histopathology

Antidiabetic activity

• Alloxan

• Measurement of blood glucose- O toluidine method, glucose
strips

• Insulin levels – RIA or ELISA

Antiinflammatory
activity

• Carageenan induced paw edema – mucopolysaccharide –Irish
sea moss Chondrus cripus

• Paw volume is measured

Neuropharmacological
activity

• CNS acting drugs: Stimulants, depressants, hallucinogens,
antidepressants, tranquillisers

• Locomotor activity in mice – activity cage – Stimulant /
depressant

• Locomotor co-ordianation

• Pentylenetetrazole convulsions in mice

ANS:

• Guinea pig ileum: nonspecific antispasmodic activity

• Isolated rat jejunum: adrenergic activity

• Rat Phrenic nerve: Muscle relaxant activity

• Frog Rectus: activity on skeletal muscle

Microbiological
assays:

• Suppress or influence the growth of microorganisms

• Cylinder/cup plate method

• Turbidimetric method

Summary

• Evaluation is a process of confirmation of identity, determination
of quality and purity, and detection of nature of adulterants

• 

Evaluation is a process of confirmation of identity, determination of quality and purity, and detection of nature of adulterants

• 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

• Chemical method includes preliminary phytochemical
screening, chemical assays to determine the purity of the crude drugs and also
the nature of adulterants in crude drugs

– Physical evaluation includes

– Moisture content

– Viscosity

– Melting point

– Solubility

– Optical rotation

– Refractive index

– Ash values

– Extractive values

– Volatile oil content

– Foreign organic matter etc

Spectroscopic
methods includes

– UV- Visible

– IR

– NMR

– Fluoresence analysis

– X ray diffraction studies etc

• Biological evaluation (Bioassay) is the estimation of
potency of drug/preparation on living organism, fungi bacteria, tissue or
entire animal

– Bioassays

– Toxic

– Symptomatic

– Tissue

– Toxic and symptomatic: animals