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178 Textbook of Pharmacognosy and Phytochemistry I
Its antigenicity can be avoided by the use of
commercial milk substitutes that are prepared
from soya bean isolates.
Injectant Allergens
Injectant allergens causes symptoms similar
to those of the antibiotics, e.g. Penicillin,
cephalosporin and semi-synthetic penicillin,
etc. Itching of the palms of the hands and the
soles of the feet, erythema and peeling of
the skin are characteristic. In severe cases
anaphylactic shock may occur.
The natural sources of injectable allergens
are produced by the sting of bees, hornets and
wasps. The allergens injected by the stings of
such insects can induce severe local and
constitutional reactions sometimes causing
death.
In addition to penicillin products, other
injectable that may cause allergies are liver
extract, antitoxins and the glandular products.
Contactant Allergens
A number of plants and their products have
been identified as the causes of contact
allergies. The plant most responsible for
contact dermatitis in North America belong to
the Ancardiaceae family, primarily the genus
Toxicodendron (Rhus) and include poison ivy,
oak and sumac. The allergen component of
these plants, called urushiols (a phenolic
compound) are found in the oleoresin fraction
and are derivatives of pentadecylcatechol or
heptadecylcatechol. Many plants of Compositae family, which include the ragweeds
also cause contact dermatitis and the
allergens responsible had been identified as
Sesquiterpenoids lactone.
Allergen plants are responsible for
considerable hazard in USA where poison ivy
are widespread as a woody vine lacquer used
for producing oriental type finish on furniture.
Its use causes industrial hazard for the
craftsman. Similar type of compounds have
been isolated from fruit pulp of Ginkgo biloba
and from the glandular trichomes of annual
Phacelia spp. (Hydro-phyllaceae) of the Californian Mojave desert. The dermatitic action of
these compound is due to the oxidation of the
allergen to quinone, which then bind with protein nucleophiles giving an antigenic complex.
Another class of chemical compound,
Sesquiterpene lactone isolated from plants of
compositae, lauraceae and magnoliaceae and
from Liverwort Frullania (Jubulaceae), causes
allergic contact dermatitis in the hypersensitive
individuals. The
to the
γγ
γ-lactone is the principle immuno-
γγ
αα
α-methylene group exocyclic
αα
chemical responsible for the allergic reaction.
Such compound (Pseudoguaianolide) is
obtained from the plant Parthenium hystero-
phorus, an aggressive weed causing public
health problems in parts of India.
Other plants species, which can give rise to
contact allergic reactions are Ruta graveolens,
asparagus, ornamental “dumb cane” (Dieffen-
bachia seguine), buck wheat, butter cups,
catalpa leaves, chrysanthemums, ginkgo
leaves, lobelia, marigolds, may-apple, osage
orange, flowering spurge, snow on the
mountains and smart weeds.
Aeroallergens, such as the various pollen
grains containing oils, trichomes from various
leaves, flowers and small fragments of plant
tissues carried by smoke originating from
brush fires, grass fires and burning leaves are
also cause for contact (allergens) dermatitis.
A number of plant products used as
additives in cosmetics and perfumes are
irritants and cause skin allergy to some
hypersensitive individuals. These types of
allergens are termed Hypoallergenic Cosmetics,
to denote this fact, the cosmetic manufacturer
add the brand names of Ar-ex, Allercreme, Almay
and Marcelle are example of hypoallergenic
cosmetics.
Certain natural products added to cosmetics
such as talcum and perfume are chief source
of contact allergy such as orris root, an
ingredient to talcum powder.
Dibromofluorescein, commonly used in
lipsticks.
Plant Products: Fibres—Cotton, Jute, Hemp 179
Wool fat (lanolin) in cosmetics, soap and
soap powders, plain detergents and enzyme
detergents, nail polishes, hair dye and hair
spray are also included among the major
causes of contact dermatitis.
Infectant Allergens
Allergy caused by the metabolic products of
living microorganism in the human body. The
continual presence of certain types of bacteria,
protozoas, molds, helminths and other
parasites in the body of human being are
responsible for chronic infection for which
patients are not aware but metabolic product
of their growth causes some patient sensitised
and the patient may exhibit allergic symptoms,
which does not response positively to routine
skin test for inhalant allergens. In such patient
bacterial metabolic waste are considered to be
infectant allergens.
The continuous presence of growth products
and metabolic waste of parasitic organism
such as hookworms, tapeworms, pinworms,
threadworms and dermatophytes are referred
as infectant allergens.
ALLERGENIC EXTRACTS
Allergenic extracts are concentrated solutions
or suspensions of allergens used for the
diagnosis and therapeutic purposes. Extracts
are aqueous (0.9% Sodium chloride used as
diluent) or glycerinated (50% glycerin as
diluent). Most preparations are buffered at pH
8 and contain phenol (<0.4%) as an antimicrobial
preservative. They are sterilised by aseptic
filtration and used as injectable products
administered in the physician’s office and for
many years were prepared by the individual
users. Commercial extracts have gradually
replaced extemporaneous preparations as
number of small speciality companies marketing
allergenic extracts several decades ago have
today disappeared with merger into larger.
Pharmaceutical companies and the several
other manufacturers of allergenic extracts are
multinational corporations.
The manufacturing of allergenic extracts
intended for international export or import
must be carried out in licensed laboratories
as per the terms and condition laid down by
section 351 of the Public Health Services Act.
Preparation
The preparation of allergenic extracts required
same general procedure and precautions
required with all parenteral products. In
addition to the general aseptic condition the
extraction process should be carried out in a
cold room. The extracts are thermolabile and
must be sterilised by aseptic filtration. Sterility
test for both aerobic and anaerobic microorganism
must be performed in guinea pigs particularly
for autogenous extracts where unknown toxic
constituents may be present.
In addition to general procedure used for
the preparations of other extractives the
following is the unique procedure for most
allergenic extracts.
Materials
The allergenic substances to be extracted are
obtained from commercial suppliers and only
the most reliable sources are selected. It should
be free from adulteration and should not
contain more than 1% of extraneous foreign
matter, prompt and proper dehydration is
important to prevent alteration of the allergens
and prevent microbial contamination.
Grinding
The material to be extracted must be ground
or subdivided for the efficient extraction of the
allergens. Materials such as hair, feathers and
textiles should be divided finely with shears.
Defatting
Many allergenic substances, including all
pollens should be defatted before final
extraction, ether and petroleum ether are most
commonly used for this purpose. It provides
clear final extract free from irritants (cotton
seed, pepper, mustard and ginger, etc.). This
defatted extract can be used in the preparation
of some patch testing substances.
Extraction
The extraction procedures are based upon the
assumption that allergens are water soluble
180 Textbook of Pharmacognosy and Phytochemistry I
proteins or glycoproteins. Extraction is carried
out normally for 24–72 hours in cold room
using sterile, pyrogen free buffered saline,
coca’s solution or similar aqueous menstrum
of pH 8.
Buffered saline
Sodium chloride 5.00 g
Monobasic potassium phosphate 0.36 g
Dibasic sodium phosphate anhydrous 7.00 g
Phenol crystals 4.00 g
Water for injection USP to make 1000 ml
Cocoa Solution
Sodium chloride 5.0 g
Phenol crystals 5.0 g
Sodium bicarbonate 2.5 g
Water for injection USP to make 1000 ml
After extraction, mixture is clarified by
coarse filtration. Some extracts are dialysed
against saline or running tap water to remove
irritants or colouring matter (e.g. house dust,
mustard, potato, spinach, beets). The processed
extract is sterilised by filtration through
cellulose membrane filter.
Freeze-dried pollen extracts: These are prepared with the same procedure except water
rather than electrolyte solution is used as
extracting medium.
Standardisation
Most allergenic extracts carry the statement
‘No US standard of potency’. The two most
common measures of allergenic potency
are weight/volume (w/v) and the Protein
Nitrogen Unit (PNU), unit of potency for
allergenic extracts. 1 mg protein nitrogen equal
1,00,000 PNU (Table 8.2).
Stability and Storage
The potency of allergenic extracts start
reducing within a matter of week or months
after their preparation, very dilute solution
tend to reduce potency by absorption to the
surfaces of containers used for packing but the
inclusion of TWEEN 80, TWEEN 20 or human
serum albumin reduce this absorption.
Table 8.2: Units of potency for allergenic extracts
Unit Description Used
Weight/volume Allergen (g) per Worldwide
(w/v) volume (mL) of
extracting fluid
Protein Nitrogen 1 mg protein Worldwide
Unit (PNU) N = 100,000 PNU
Allergy Unit Skin testing US
(AU) to end point
Biological Unit Skin testing relative Europe
(BU) to histamine
All the allergenic extracts should be refri-
gerated at 2–8°C and freezing should be avoided.
Expiry Date
Aqueous extract 18 months
Glycerinated scratch test 3 years
and bulk extract
Lyophilised products 4 year
After reconstitutions 18 month
Pollen extracts
Pollens are the most common cause of atopic
disease in most parts of the country, but
allergens vary somewhat with the region.
Therefore allergen extracts prepared from
some of the common pollens (e.g. rageweed,
several grasses and tree) have been among the
most widely studied and it has been reported
that these products are reliable for both
diagnosis and in several cases for therapeutic
use when properly prepared (Table 8.3).
Dust Extracts
The allergens in house dust are not related to
the inorganic dirt from outside but to the
products of aging and decompositing materials
in and around the house. The dust for
commercial extracts generally is obtained from
house cleaning or rug cleaning firms and is
pooled to get some homogencity.
Dust mites are of more concern, as mites are
more responsible for most dust allergy.
Standardised extract of Dermatophagoides
species are available. The dust mite is
Plant Products: Fibres—Cotton, Jute, Hemp 181
Table 8.3: Pollen extracts
TREES
Acacia Elderberry Osage orange
Alder, grey Elm, American Palo verde
Almond Eucalyptus Peach
Apple Hackberry Pear
Apricot Hazelnut Pecan
Arbor vitae Hemlock Pepper tree
Ash Hickory Pine
Bayberry Hop-hornbeam Plum
Beech Ironwood Poplar
Birch, spring Juniper Privet
Birch, white Locust Redwood
Bottle brush Maple Russian olive
Box elder Melaleuca Spruce
Carob tree Mesquite Sweet gum
Cedar Mock orange Sycamore
Cherry Mulberry Tamarack
Chestnut Oak, white Tree of heaven
Cottonwood Olive Walnut
Cypress Orange Willow
GRASSES
Bahia Corn Redtop
Barley Fescue, meadow Rye grass,
perennial
Beach Grama Salt
Bent Johnson Sorghum
Bermuda grass June grass Sudan
Bluegrass, Koeler’s Sweet vernal
Kentucky grass
Brome Oats Timothy grass
Bunch Orchard grass Velvetgrass
Canarygrass Quack Wheat
Chess Wheatgrass
WEEDS AND GARDEN PLANTS
Alfalfa Fireweed Poppy
Amaranth Gladiolus Povrtyweed
Aster Goldenrod Quailbush
Balsam root Greasewood Ragweed, giant
Bassia Hemp Ragweed, short
Beach bur Honeysuckle Ragweed,
western
Broomweed Hops Rose
Burrow brush Iodine Bush Russian thistle
(Con...)
Table 8.3: Pollen extracts (Con...)
Careless weed Jerusalem oak Sagebrush
Castor bean Kochia Saltbrush
Chamise Lamb’s quarters Scale
Clover Lily Scotch broom
Cocklebur Marigold Sea blight
Coreopsis Marshelder Sheep sorrel
Cosmos Mexican tea Snapdragon
Daffodil Mugwort Sugar beet
Dahlia Mustard Sunflower
Daisy Nettle Western
waterhemp
Dandelion Pickleweed Winter fat
Dock Pigweed Wormseed
Dog fennel Plantain, English Wormwood
distributed universally and is usually found
in furnishing stuffed with vegetable fibres (e.g.
cotton) (Table 8.4).
Table 8.4: Dust extracts
House dusts Dust mites
• House • D. farniae
• Mattress • D. pteronyssinus
• Upholstery • Mite mix
• Cedar and red cedar
• Cotton gin
• Oak
• Grain elevator
• Padauk
• Wood dusts
Fungal Extracts
Fungi are omni present and may be found
in the home on textiles, leather goods,
upholstered furniture, food and plants.
Therapy should include efforts to create mold
and fungi free environment. The allergenic
extracts are prepared variously from
mycellium, medium or both but little know
how is available of fungal allergenic extracts
preparation method. Some of the fungal and
mold allergen extracts available are given in
the Table 8.5.
182 Textbook of Pharmacognosy and Phytochemistry I
Table 8.5: Fungal extracts
Alternaria Mucor
Aspergillus Mycogone
Botrytis Nigraspora
Cephalosporium Penicillium
Cephalothecium Pullularia
Cladosporium Rhodotorula
Curvularia Rusts
Epidermophyton Saccharomyces
Fusarium Spomdylocladium
Gliocladium Trichoderma
Helminthosporium Trichophyton
Hormodendrum Verticillium
Microsporium
Insect Extracts
Sensitivity testing and immunotherapy are
commonly recommended and employed for
the stinging insects. The venom extracts have
been shown to be highly effective when
properly employed. The list of the standardised
extract is given in Table 8.6.
Table 8.6: Standardised extract
INSECT EXTRACTS
Stinging insect: Whole body
• Ant black
• Ant red
• Ant carpenter
• Ant mix (black/red)
• Ant fire
Stinging insect: Venom protein
• Honeybee
• Yellow hornet
• Wasp
• White faced hornet
• Mixed verpid
INHALANT ALLERGY TO INSECT
Blackfly Horsefly Spider
Butterfly Housefly Sow bugs
Cockroach Mosquito Waterfly
Daphnia Moth
Fruitfly Mushroomfly
Miscellaneous Inhalant Extracts
Miscellaneous allergens are those other than
pollen, dust and molds that cause atopic
allergies, these includes epidermal from
domestic animals (cat, dog and horse). The
number of other inhalant allergens is remarkable
(Table 8.7).
Table 8.7: Miscellaneous inhalant extracts
MAMMALIAN EPIDERMAL/FEATHERS
Camel Chicken Pigeon
Cat hair Dog Goose
Cat pelt Goat Duck
Deer Guinea pig Parakeet
Canary Hog
MISCELLANEOUS INHALANT
Acacia Hemp fibre Orris root
Algae Henna Silk
Cartor bean Guar gum Sisal
Cotton seed Jute Tobacco leaf
Derris root Leather Tragacanth
Grain dust Lycopodium Wood dust
FURTHER READING
1. Hallucinogenic Plants: A Golden Guide (pdf)
June 15, 2010 https://anthrome.wordpress.com›
2010/06/15›hallucinogenic-plants-a-g.
2. Hallucinogenic Plants: A Golden Guide by
Richard Evans Schultes, Elmer W. Smith
(Illustrator).
3. Kalia AN. Textbook of Industrial Pharmacogonsy.
(2005). CBS Publishers and Distributors, New
Delhi.
4. Richard F Keelar. Effects of Natural Teratogens
in poisonous plant on Fetal Development in
Domestic Animals. Drugs and Fetal Development.
1970:107–25.
5. Schultes RE. 1976. Hallucinogenic plants. Golden
Press.
6. Tyler VE, Brady LR, Robbers JE. 1988. Pharmacognosy, 9th Edition-Leo and Fabiger. Philadelphia.
7. Evans WC. 2009. Trease and Evans Pharmacognosy, 16th ed., Elsevier; New York.
9
Primary Metabolites
Plants produce two types of metabolites,
primary and secondary metabolites.
Primary metabolites involved directly in
growth and metabolism, and they are
produced by each and every plant irrespective
of their genera and family, e.g. carbohydrates,
lipids and proteins, etc.
The secondary metabolites are the end
products of the primary metabolism not
involved in metabolic activity of plants,
they are toxic but defensive for the plants.
Secondary metabolites are gene specific and
not common for all plants, e.g. alkaloids,
glycosides, phenolics, steroids and essential
oils.
Carbohydrtes are the primary plant products
biosynthesised by photosynthesis, from water
and carbon dioxide in the presence of sunlight.
They can be grouped into sugars and
polysaccharides.
Sugars are water soluble and more or less
sweet in taste. They are monosaccharide or
oligosaccharides.
Monosaccharide are sugars containing from
three to nine carbon atoms, but sugars with
five or six carbon atoms (pentose, C
Hexoses, C
quantity in plants, e.g. glucose, fructose or
oligosaccharides.
6H12O6
) are accumulated in large
5H10O5
and
Saccharides containing from two to ten units.
They are derived from two, three, four to ten
monosaccharides molecules, respectively with
the elimination of two, three, four to ten
molecules of water respectively. They can also
be known as di-, tri-, tetra-saccharide or
pentasaccharides depending on the numbers
of monosaccharides involved in formation.
One of the commonest plant di-saccharides is
sucrose.
The monosaccharides units in oligosaccharides
may be different or same.
These are high molecular weight polymers
formed by condensation of large number of
monosaccharides molecules in a exactly
similar manner to the formation of di-, tri- or
tetra-saccharides. Each sugar is linked with its
neighbour sugar through a glycosidic linkage
formed by the theoretical elimination of water
molecule between the hemiacetal hydroxyl
group C-1 of one sugar molecule with any of
the hydroxyl group of other sugar molecule.
The hydrolysis of polysaccharide, by enzyme
or reagents, breakdown into pentose, hexose
or their derivatives.
They are responsible for the rigidity of cell
wall in higher plants (cellulose) or the
flexibility of the thallus of lower plant (Algae)
or as energy storage forms (starch in plants
and glycogen in animals). Other substances
also occur along with cellulose (primary cell
wall) are the hemicelluloses which are also
183
of high molecular weight polysaccharides but
are more soluble and easily hydrolysable than
cellulose. Closely related to hemicelluloses are
gums and mucilages, which are also important
group of drugs and pharmaceuticals. Pectin
is also an another form of polysaccharide
associated with cellulose, having pharmaceutical
importance.
Chemistry: Chemically carbohydrates are
polyhydroxy aldehydes or ketone containing
carbon, hydrogen and oxygen. The proportion
of hydrogen and oxygen is the same as that is
in of water (H
(C
nH2nO)n
or CH2O.
O). The general formula
2
The oxidation product is the corresponding
carboxylic acid –COOH, i.e. oxidation product
of glucose is uronic acid and of galactose is
galacturonic acid.
Sugars and starch are important product in
the economy of mankind. They are used as
food and pharmaceuticals.
Molisch test: All the carbohydrates give purple
colouration on treatment with molisch
reagent (1% alcoholic solution of α naphthol)
along with sulphuric acid, poured down on
the side of test-tube: in the case of soluble
carbohydrates a deep violet colouration is
produced where the liquids meet, in the case
of insoluble carbohydrates (cellulose) colour
will appears on shaking the test mixture.
Sulphuric acid test: Heat small quantity (0.2 g)
of carbohydrates with 1 ml of concentrated
sulphuric acid (H
)on a small flame,
2SO4)
immediate blackening will take place.
Action with sodium hydroxide: Boil a small
quantity of (0.2 g) of carbohydrates with about
5 ml of 10% (w/v) sodium hydroxide solution
(NaOH); the solution turns yellow, then brown
and emits the caramel smell with soluble
carbohydrates but insoluble carbohydrates
will not give colouration.
Fehling solution test: Add 5 ml of carbohydrate solution to 5 ml of freshly prepared
fehling solution (Fehling solution A & B in
equal quantity) and boil. Reduction will take
place with the formation of red colour
precipitate of cuperous oxide with reducing
sugars. while non reducing carbohydrates
(sucrose and polysaccharides) will appear on
hydrolysis as on hydrolysis non-reducing
sugar will be converted into reducing sugars
but precaution to be taken to neutralise the any
acid used for hydrolysis before adding fehling
solution.
Resorcinol test for ketones: Carbohydrates
solution with equal volume of concentrated
sulphuric acid heated on water bath in the
presence of resorcinol crystal. Appearance of
rose-red colour show the presence of ketones,
e.g. fructose and honey.
Test for pentose: Solution of carbohydrate with
equal volume of hydrochloric acid and phloroglucinol is heated on water bath, appearance
of red colour indicate the pentose sugar, e.g.
D-ribose, D-arabinose, D-xylose and xylulose.
Source: Dried gummy exudates obtained
from the stem and branches of Acacia senegal
Linn; and other species of Acacia, family
Leguminosae.
It is commonly known as gum Arabic.
Geographical source: Sudan, central and west
Africa (chiefly Senegal) and Nigeria.
Method of preparation: Most of the official drug
comes from cultivated tree in Kordofan (Sudan).
Collection: Gum is collected from 6 to 7 year
old tree after the rainy season till the next year
rains. Lower branches from the tree are
removed at the time of leaves wilting and
falling down. The trees are trapped by making
transverse cut in the bark with sharp axe,
avoiding damage to the cambium and
xylem. A strip about 1.5 to 2.5 feet long and 2
to 3 inches in breadth is removed. Gum start
exudating immediately in hot weather while
in cold weather it is slow in exudation. On
exudation gum solidify in the form of tears and
remained adhere to the tree. The tears are
removed after 2 to 3 weeks of trapping,
sbsequently transferred to grading house
where they are graded, cleaned and
bleached.
Primary Metabolites 185
Cleaning means picking by hand and removal
of adherent fragments of bark followed by
shifting of tears.
Bleaching: The tears are spread in thin layers
on canvas and exposed to sunlight for two to
three weeks; during this process small cracks
developed on the outer surface of the tears and
make them opaque in appearance. Whereas,
the unbleached tears are glassy in appearance
and termed natural ungraded gum containing
all sorts of tears and fragments is called sorts.
Graded tears are packed in jute bags and marketed.
Chemistry: Raw gum contain 10 to 15% water,
some tannins (in coloured gum only), oxidase
enzyme but no starch. The chief constituents
of gum acacia mainly consists of arabin (Acidic
polysaccharide) which is complex mixture of
calcium, and to less extent, of magnesium and
potassium salt of arabic acid. Which on
hydrolysis with dilute sulphuric acid gives
sugars [l-rhamnose (18%), d-galactose (32%),
l-arabinose (38%)] and d-glucuronic acid. The
uronic acid residue represent about 18% of the
gum. Peroxidase and carboxydase (oxidase
enzymes) are also present.
Evaluation: The good quality gum is almost
colourless translucent and striated. The
medium grade has marked pinkish tingue,
while lower grade of gums are dark and
having few fragments of bark.
B.P. requirement include limit of insoluble
matter and loss on drying not more than 15%.
It should be free from tragacanth and starch.
Ash value between 2.7 and 4%. Taste—blanded.
Fracture—Freshly fractured surface is glassy
and odourless, otherwise tears are opaque or
pale-yellow colour.
Chemical test: Solubility test: It is almost
completely soluble in equal weight of water the
solution is slightly viscous and mucilaginous,
pH slightly acidic in cold water solution but
in hot water acidity increases, on dilution with
water no sedimentation on standing. Solution
is levorotatory.
Test for the absence of tragacanth and agar:
Aqueous solution (10% w/v), of gum acacia
do not give precipitation with dilute solution
of lead acetate.
Test for the absence of starch and dextrin: Ten
percent aqueous solution of gum acacia do not
give blue or red colour with weak iodine solution.
Peroxidase enzyme: Blue colour with benzidine
solution.
Sucrose and fructose: Aqueous solution
(10% w/v) do not give any colour with chlorohydric resorcinol (resorcinol-hydrochloric acid).
Absence of tannins: No blue colour with ferric
chloride solution.
Uses: It is used as suspending agents and
binding agent in pharmaceutical formulations.
It is compatible with other plants hydrocolloids.
It is used as a substitute of gum acacia. It is
obtained from Anogeissus latifolia Wall, family
Combretaceae.
This gum is viscous exudates of wild forest
tree of India and Sri Lanka. Its tears are
vermiform and show fewer cracks even less
than gum acacia.
It is a complex polysaccharide which
contains d-mannose, d-galactose, l-arabinose,
d-xylose, d-glucuronic acid. It very often
contains tannins
Water produce more viscous solution hence
used as emulsifier and stabiliser.
Solubility—Approximately 90% of the product
is water soluble.
Purity Tests
Borax test: Aqueous solution of gum acacia
(10 g in 15 ml of water) should be translucent
but not glairy. To 5 ml this solution add 0.1 g
of borax (in solution form) stiff translucent
mass will form with acacia gum and Indian
gum but not with tragacanth.
Lead sub-acetate test: To dilute solution of
mucilage (1 : 4 dilution) add few drops of lead
sub-acetate solution.
Acacia gum will give thick precipitate;
Indian gum and Tragacanth mucilage will
yield only slight precipitate.
Test for oxidase enzyme: To 5 ml of mucilage
add few drops of 1% solution of guaiacum
resin in alcohol.
Acacia gum mucilage will show blue colour,
similar colour develop in Indian gum mucilage
however no colouration in tragacanth
mucilage.
Biological source: It is dried gummy exudates
obtained by incision from the trunk and
branches of Astragalus gumifer Lbill, family
Fabaceae (Leguminoseae) and other species
of Asiatic Astragalus; A. kurdicus Bioss, A.
gossypius and more. The better grade tragacanth
known as Persian Tragacanth.
Geographical source: More than 2000 species
are known but gum produce from thorny
subshrub found at the height of 2000 to 3000 M
in the mountaneous district of Anatolia, Syria,
Iran, Iraq and USSR.
Peparation: A transverse incision is given at
the base of the stem of a two years, old plant
with sharp knife having a thin cutting edge; a
wedge-shaped wooden piece inserted into the
injured trunk to keep the wound open, after
24 hours wooden piece is removed gum start
exuding with force (gum produced by
gummosis process).
Fresh gum is white in colour but on
exposure to air, water gets evaporated and
it gradually harden and change in colour,
the shape of the gum depends upon the
incision, The gum exuding from the natural
injury is of worm like and twisted into coil
known as Vermiform tragacanth of ¾ inch in
length.
To increase the yield of exudates, in some
countries, plant are burnt at the top after
having injury/incision, the quantity of the
yield may be increased but quality of the
product is poor therefore this process is not
followed by many of the countries.
Description: The official Persian Tragacanth
is odourless, tasteless, flattened white ribbonshaped, about 25 mm long and 12 mm wide
and 1 mm thick, horny with transverse
striation on the surface (indicate the stoppage
of flow). Microscopically, the powder dug
shows the presence of rounded starch granules
(4.5 to 10 μm) with central hilum.
Commercially tragacanth is available in
number of grades; No. 1: colourless flate
ribbons; No. 2 White flat ribbons; No. 3 Light
cream curly ribbons; No. 4 Cream coloured flat
ribbons; No. 5 Pinkish coloured ribbons. As
the colour darkens grade No. increases, as
ambered-coloured are graded as No. 28
whereas reddish brown coloured ribbons are
graded No. 55, etc. the good quality form
the official drug while the lower grades are
used as food, laxative and for industrial
purposes.
Chemistry: Gum tragacanth is cosidered to be
a mixture of two polysaccharides (tragacanthin
and bassorin), starch (3%) and about 3 to 4%
minerals but does not contain oxidases
enzymes. Tragacanthin is neutral and soluble
in water and alcohol mixture and dissolve in
water to form colloidal solution. The bassorin
part is acidic, incompatible with ethyl alcohol
but swells in the presence of water to form gel
(60 to 70%).
Tragacanthin is a demethoxylated bassorin;
about 30% of the gum is an arabinogalactan
and have galactose backbone; the bassorin
(tragacanthic acid) on the other hand cemically
is partially methylated glycano galacturonan
built from four monosaccharides: D-galacturonic
acid, D-galactose, D-xylose and l-fucose. The
central backbone of the molecule is chain of
1,4-linked galacturonic acid; the chain is
substituted by disaccharides (fructoxylose or
galactoxylose).
The Persian Tragacanth contains traces of
starch while the unofficial grade contain more
starch and give blue colour with weak iodine
solution. Tragacanth hydrocolloid is resistant
to acid hydrolysis hence preffered for use in
highly acidic conditions.
BP limit foreign matter to 1.0% and microbial
limit test.
Storage: To be stored in cool and dark room,
protected from microbial contamination.
Uses: In pharmaceutical formulation as
suspending agent. In cosmetics as a demulscent
and an emollient. Dilute solution (0.5 to 1.5%)
of tragacanth is very viscous and stable in acid
pH and heat, compatible with most plant
Primary Metabolites 187
hydrocolloids, and easy to conserve hence
good stabiliser for suspension and as
emulsion. It is also used in textile industry in
cloth printing and in confectionary.
Solubility test: Tragacanth is partially soluble
in water (distinction from acacia and agar).
Mucilage formation: It forms mucilage with
water (1 : 20 H
O) on boiling.
2
Iodine solution test: On boiling with strong
solution of iodine tragacanth develops green
colour.
Ferric chloride solution test (10 %w/v): Deep
yellow colour precipitate will appear.
Lead acetate solution test: Tragacanth solution
will give heavy precipitate with strong solution
of lead acetate.
Alcoholic potash solution test: On warming
the solution of tragacanth with alcoholic
potash solution will produce canary yellow
colour.
Ruthenium red solution test (0.1% w/v): No
pink stain will be developed with the
ruthenium red solution.
Test for reducing sugar: Hydrolyse the
tragacanth solution (4 ml) with hydrochloric
acid (1 ml), on heating at water bath for an
half hour. Divide the hydrolysed mixture into
two portion.
To one portion add 1.5 ml of sodium
hydroxide (NaOH) to neutralise solution,
followed by the addition of Fehling solution
3 ml and heated on water bath—appearance
of red coloured precipitate indicate the
presence of sugar.
The second portion add a few ml of barium
chloride solution—no precipitate formation
distinct it from Agar.
Agar is the dried gelatinous substances
obtained from decoction concentrates of
Gelidium cartilagineum (Linn) Gaillon, family
Gelidiaceae and other species of Gelidiaceae.
It is also refered to as Japanese isinglass
obtained from Gelidium amansii spp. and
related red algae (class Rhodophyceae).
Geographical Source: Most of the commercial
supply comes from Korea, South Africa, both
Atlantic and Pacific coasts of USA, Spain,
Mexico and New Zealand.
Method of preparation
Method of preparation is divided into four
steps:
1. Collection of algae (seaweeds)
2. Cleaning of seaweeds
3. Bleaching
4. Conversion to strips.
Collection of algae (seaweed): Collection is
done from two sources; cultivated and natural
source, grown on rocks in shallow water.
Cultivation carried out in special areas by
planting poles in the sea as support for the
development of seaweed, poles being
withdrawn and algae stripped off.
From the shallow water algae is collected
by using small boats either by diving or by
using long handeled rackes, collection is done
in summer.
Cleaning: The collected algae is taken to seabeach, dried in sun, shaken to remove dust,
sand and shell, etc. adhered; bleached partially
by washing and exposure to sun.
Bleaching: Partially bleached algae spread on
loosely made bamboo tray or plateform, and
exposed to sun, during the process it is being
washed from time to time during exposure
until it is almost colourless.
Extraction
Extraction of algae is obtained by decoction
process. It is carried on in winter season in two
steps.
First step decoction is done by boiling the
bleached algae in acidified water (1 : 60) in
kettles for several hours to get viscid product,
while it is hot passed through coarse strainer
to remove the undissolved material and then
by reheating, it is passed through Linen bags
into trays, allowed to cool and set to form jelly
followed by cutting into bars.