Herbs as raw material


Source of herbs

Identification and authentication of herbs


At the
end of this lecture, student will be able to

Discuss the source of herbs, selection, identification
and authentication of herbal materials


Ø  The
word herb derived from the latin word herba – Grass/green stalks

Ø  Herbs
include any part of the plant like leaves, roots, stem, bark etc posses
therapeutic  activity

Herbal medicine:

Ø   Branch of science deals with medicinal
plants, it includes modern standards of testing of herbs and medicines derived
from natural sources

Herbal Medicinal product:  Defined as any medicinal product, exclusively
containing one or more active ingradients of herbal origin

Herbal Drug Preparations

Ø   Preparations which are made from herbal
drugs and are prepared by the help of different processes like infusion,
decoction, maceration, distillation, fermentation etc. These include whole
plant/parts, powdered herbal drugs, extracts, essential oil, processed exudates
of herbal materials

Source of herbs:

Ø  Plants
have ability to synthesize wide variety of chemical compounds that are used to
perform important biological functions and to defend against attack from
insects, fungi and herbivorous

Ø   Many of these phytochemicals  have beneficial effects on long term health
when consumed by humans and can be used to treat diseases effectively

Ø   Phytochemicals are divided into Primary
metabolites and secondary metabolites

Ø  Primary
– Cabohydrates, proteins and lipids found in all the plants

Ø  Secondary
Compounds which have
therapeutic actions, do not have any role in the growth of plants

Eg: Alkaloids, glycosides, tannins, resins, volatile oil,
latex etc

Quinine – Anti malarial

Reserpine – Anti hypertensive

Digitoxin – Cardiac stimulant

Identification and authentication of herbal materials:

Ø  Herbal
materials may vary in composition and properties unlike conventional
pharmaceutical products, which are generally prepared from synthetic,
chemically pure compounds by means of reproducible manufacturing techniques

Ø   Correct identification and quality assurance
of the starting material is essential for safety and efficacy of the drug

Ø   Drugs of poor quality destroys the clinical

Ø  Taxonomic

Ø   Herbarium sample

Ø   Macroscopic method

Ø  Microscopic

Ø   Physico chemical method

Ø   Spectroscopic method

Ø   Chromatographic method

Taxonomic method:

Ø  Involves
classical botanical methodologies for collection and documentation of the
plant at its source

Ø   Botanical origin of the drug is identified and
its scientific binomial, that is genus, species is determined based on this

Ø  Information
such as vernacular names, site of collection, detail of collector, season of
collection, part collected etc are essential fundamentals even before

Herbarium coupon sample:

Ø  Sample
of collected material should be kept as a coupon sample in a herbarium or in a
research institute for future reference

Ø   Specimens collected from field were dried
using blotting paper and uniform pressure was exerted on blotting papers by
placing them in a plant press

Ø  Blotting
paper was changed every day (15 days), so that moisture from the specimen is
removed completely

Ø  After
demoisturing, specimens were treated with a solution of HgCl2 in
formalin for about 2 min. They were again dried in dryers and mounted on
herbarium sheet using fevicol

Morphological method:

          Refers to shape, size, colour, odour, taste
and special features like texture and fracture

     Shape:   Nuxvomica – disc

Aconite – conical

     Colour:   Fennel – greenish yellow

Senna- greenish

      Odour:   Umbelliferous fruits – aromatic

                      Asafoetida – alliaceous

Licorice – Sweet

Kalmegh – Bitter

Kurchi – granular

Picrorrhiza- tough


 To identify
unorganized drug by their known histological characters

by virtue of its property to magnify, permits the     minute structure under study to be

 Stains can be
used to distinguish cellular structure

              – Phloroglucinol and
con HCl –  Lignin (Pink)

               – Ruthenium red –
mucilage (Pink)

Histological studies – thin section of drugs

 Cell wall,
cell contents, stomata, trichomes, fibres, vessels etc

       Eg:   Senna – Paracytic stomata

                Vasaka – Diacytic

                Nuxvomica – lignified unicellular

                Senna – Warty
unicellular trichomes

                Datura –
multicellular unbranched trichome

                 Vasaka –
unicellular glandular trichome

Ø  Microscopic linear measurements and
quantitative microscopy

     Stomatal number: Average number of
stomata per sq mm of epidermis of the leaf 

     Stomatal index : Percentage which
the number of stomata form to the total number of epidermal cells; each stoma
being counted as one cell                    

                                          S.I =
S.I = 
Stomatal index

S = No of stomata

= No of epidermal cells in the same unit area          

ratio : 
Average number of palisade cells beneath each epidermal

number : 
The number of vein islets per sq mm of the leaf
surface midway between the midrib and margin

chemical method:

                 Moisture content


                  Melting point


                  Optical rotation

Refractive index

                   Ash content

                  – Extractive value

                  – Volatile oil content


Ø    Infrared spectroscopy

Ø   Electron spectroscopy for chemical analysis

Ø   Atomic absorption Spectroscopy

Ø   X Ray diffraction analysis

Ø   X-Ray fluorescence analysis





Ø   Gas Chromatography


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