Pharmacognosy Unit -7 PDF | PPT

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Unit -7

Year – 1st

Prepared by-

Divesh verma










By Divesh verma
Sadbhavna college of Management & Technology


Surgical fibres, sutures and surgical dressing

Fibres – the term fibres is used for surgical dressing include both natural and artificial fibres and
embraces epidermal trichomes , such as cotton fibres and other cell of the plan and animal products
such as wool and silk. All natural fibres are made up of long chain molecules . these can grouped as
under .

a. Vegetable fibres – cotton , flax, hemp, jute, oxidised cellulose and methyl cellulose .
b. Regenerated from carbohydrates – viscose rayons.
c. Animal fibres- wool and slik
d. Synthetic fibres – nylon, terylene
e. Mineral fibres – asbestos and glass.


Difference between vegetable and animal fibre

Vegetable fibres Animal fibres
1. No foul smell is produced on ignition 1. They give foul smell on ignition

.they burn with blackish smoke
2. Give violet colour with molisch reagents 2. No violet colour is produced with

moilsch reagents
3. On boiling with picric acid no yellow 3. On boiling with picric acid yellow stain is

stain is produced produced

4. No red colour is produced with million 4. red colour is produced with million
reagents reagents



Raw cotton, purified cotton, absorbent cotton.

Biological Source
Epidermal trichomes of the seeds of cultivated species of the Gossypium herbaceum and other
species of Gossypium (G. hirsutum, G. barbadense) freed from impurities, fats and
sterilized, belonging to family Malvaceae.

Geographical Source

United States, Egypt, some parts of Africa, and India.

Colour – White
Odour- Odourless
Taste -Tasteless

By Divesh verma
Sadbhavna college of Management & Technology


Shape- These are fi ne fi laments like that of hair, which are soft and unicellular.
Size- 2.2–4.6 cm in length and 20–35 micron in diameter

Chemical Constituents
It consists of 90% of cellulose, 7–8% of moisture, wax, fat and oil 0.5% and cell content about
0.5%. Purified cotton has almost cellulose and 6–7% of moisture.

Chemical Tests
1. On ignition, cotton burns with a flame, gives very little odour or fumes, does not produce a
bead, and leaves a small white ash; distinction from acetate rayon, alginate yarn, wool, silk, and
2. Dried cotton is moistened with N/50 iodine and 80% w/w sulphuric acid is added. A blue
colour is produced; distinction from acetate rayon, alginate yarn, jute, hemp, wool, silk, and
3. With ammoniacal copper oxide solution, raw cotton dissolves with ballooning, leaving a few
fragments of cuticle. Absorbent cotton dissolves completely with
uniform swelling, distinction from acetate rayon, jute, wool, and nylon.
4. In cold sulphuric acid (80% w/w) cotton dissolves; distinction from oxidized cellulose, jute,
hemp, and wool.
5. In cold sulphuric acid (60% w/w) cotton, is insoluble; distinction from cellulose wadding and
6. In warm (40°C) hydrochloric acid it is inso luble; distinction from acetate rayon (also silk,
7. It is insoluble in 5% potassium hydroxide solution
Cotton is used as a filtering medium and in surgical dressings. Absorbent cotton absorbs blood,
pus, mucus, and prevents infections in wounds.


Biological Source
It consists of phloem fibres from the stem of various species of the Corchorus; C. capsularis
Linn, C. olitorius Linn, and other species like C. cunninghamii, C. junodi etc., belonging
to family Tiliaceae.

Geographical Source
West Bengal and Assam.

They are tall, usually annual herbs, reaching to a height of 2–4 m, unbranched and if branched it
has only a few side branches. The leaves are alternate, simple, lanceolate, 5–15 cm long and a
finely serrated or lobed margin. The flowers are small (1.5–3 cm in diameter) and yellow, with
five petals; the fruit encloses many seeds in the capsule.

By Divesh verma
Sadbhavna college of Management & Technology


Retting is the process for the preparation of bast fibres. This process is done by three methods,
that is, microbial (or water), steam, and mechanical process. The microbial or water retting
process is the oldest and the popular method employed for the breaking of lignin bond present
between parenchyma and sclerenchyma. The breaking of this bond facilitates the easy
procurement of skin from its core. Then the material is washed dried to release pectin bond
which makes the hard skin to fine thread like fibres. The jute fibres are graded according to its
colour, strength and fibre length. The fibres are of white to brown and 1–4 m. long.

Chemical Constituents
Jute fibres are composed primarily of the plant materials cellulose and lignin. Jute is composed
of about 50–53% cellulose, nearly 20% of hemi cellulose and 10–11% of lignin along with other
constituents like moisture not more than 12–13%, fats, wax, and ash contributing to 1% each.

It has a large range of use (about 1,000 uses). It is listed as the second most important vegetable
fibre after cotton. Jute is used chiefly to make cloth for wrapping bales of raw cotton, in the
preparation of sacks and coarse cloth. They are also woven into curtains, chair coverings,
carpets, Hessian cloth very fine threads of jute can be made into imitation silk and also in the
making of paper. It is even used in the manufacture of tows, padding splints, filtering, and
straining medium. Jute is used for the preparation of coarse bags.

Biological Source
It is the pericyclic fibres which are removed from, the stem of Linum usitatissimum Linn.,
belonging to family Linaceae.

Geographical Source
It is mainly found in United States, Russia, Ireland, Northern Europe.
The length of fibre cells ranges from 1.2 to 5.0 cm and the length of fibres cell bundles ranges
from 30 to 90 cm. The short and broken fibres are called ‘tow’. Flax is hygroscopic in nature.
Flax fibre is soft, lustrous and flexible. It has more tensile strength than cotton fibre but less

Chemical Composition
The flax chiefly consists of pecto-cellulose.

Linen cloths can be prepared which is used as a filtering medium. The ‘tow’ is used in making
coarse fabrics and cordage, while the long fibres are used for strong threads and fine linens. Flax
fibre is also utilized as raw material for the high-quality paper industry for the purpose of printed
currency notes and cigarette paper.

By Divesh verma
Sadbhavna college of Management & Technology


Biological Source
Fibres obtained from the cocoons spun by the larvae Bombyx mori Linn., belonging to family

Geographical Source
China, France, Iran, Italy, Japan, and India.

One gram of silk-worm egg consists of around 15,000 eggs which are kept at 0°C to overcome
the immature development. The silkworms eat mulberry leaves day and night and they grow very
fast. When the colour of their heads changes darker, it indicates that the time for them
to moult has come. It require almost a month time for its development into full size. During this
period it takes four moulds and their body turns slightly yellow reaching a size of 4 cm long. The
silk-worm finally eats a meal which is about twenty to twenty five times its weight of leaves and
attains a size of 9 cm length and 10 mm thick. The skin becomes tight and all these symptoms
indicate that it is going to cover itself with a silky cocoon. The process of spinning cocoon
continues for almost three days. After 7–8 days, the larvae changes into chrysalides, and the
cocoons are collected by throwing them into boiling water, this kills the silkworms and also
makes the cocoons easier to unravel. If the caterpillar is left to eat its way out of the cocoon
naturally, the threads will be cut short and the silk will be useless. The cocoons are kept in hike
warm water to remove the gum. Since all the eggs hatch almost the same time, the cocoons also
be collected together and treated at the same period. Some amount of cocoons are retained and
allowed to come out for fertilization. The females lay nearly 500 eggs and these eggs are stored
till further requirement is wanted.

Colour – Yellow
Size – 5 to 25 microns in diameter and 1,200 metre
in length
Appearance – Fine, solid, smooth to touch
Solubility – Soluble in cuoxam, in cold dilute sulphuric
Extra features- Hygroscopic in nature and has good elasticity
and tensile strength.

Chemical Constituents
Silk mainly consists of protein known as fibrion. Fibrion is soluble in warm water and on
hydrolysis yields two main amino acids, glycine and alanine.

Silk is used pharmaceutically in the preparation of sutures, sieves, and ligatures. The ‘stiff
silkworm’ (dried body in the four to fifth stage of larva, which dies due to infection
of the fungus Beauveria bassiana) is used in the traditional Chinese medicine.

By Divesh verma
Sadbhavna college of Management & Technology


Biological Source
Wool consist of hairs from the fleece of sheep Ovis aries Linn., belonging to family Bovidae.

Geographical Source
The worlds leading producers of wool are Australia (25%), China, and New Zealand (11%),
while Turkey, Iran, India, and the United States (Texas, New Mexico) contribute to 2%.

Wool is the fibre derived from the hair of animals of the Caprinae family, mainly sheep and
goats. It is produced as the outer coat of sheep. The fibre obtained from domestic sheep has two
qualities which differentiate it from hair or fur. The fibres have scales which overlap like
shingles on a roof and it is crimped. The amount of crimp is directly proportional with the
fineness of the wool fibres and the fine wool (like merino) have up to a 100 crimps per inch,
whereas coarser wools (like karakul) have one or two crimps per inch. The hairs from sheep are
removed during the shearing time. After shearing, the wool is separated into five main
categories: namely fleece, pieces, bellies, crutchings, and locks. It is then cleaned from dirt and
high level of grease (thus ‘greasy wool’) which contains valuable lanolin is present on the hair.
The grease is generally removed for processing by scouring with detergent and alkali. The wool
is then treated with hydrogen peroxide for bleaching, it is then washed properly and spreaded on
wire nettings and dried under hot air.

Wool is generally a creamy white colour but some of the breeds of sheep naturally produce
black, brown (also called moorit) and grey coloured wool. The wool is smooth, elastic, slippery
to touch and slightly curly. Diameter of wool varies from 15 μm (superfine merino) to 30 or 40
μm. The finer the diameters the greater its value is. Wool is soluble in warm alkaline solutions,
but not in dilute or strong acids.

Chemical Constituents
Wool mainly consists of a sulphur containing protein called keratin. Keratin is composed of
amino acid like cystine.

Chemical Tests
1. Solubility test: It is easily soluble in warm alkali.
2. Wool when treated with Con. Hydrochloric acid, it does not produce any effect but dissolves
3. When treated with cuoxam solution, it does not dissolve but swells the wool and produces blue
4. Solution of wool treated with lead acetate produces black precipitate due to high sulphur
It is used as a filtering aid and straining medium and in the manufacture of clothing, carpeting,
felt and it is also used to absorb odours and noise in heavy machinery and stereo speakers.

By Divesh verma
Sadbhavna college of Management & Technology