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 metabolites – Cabohydrates, proteins and lipids found in all the plants

Ø  Secondary Metabolites:  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 efficacy

Ø  Taxonomic method

Ø   Herbarium sample

Ø   Macroscopic method

Ø  Microscopic method

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 method

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

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

          Taste:      Licorice – Sweet

                           Kalmegh – Bitter

          Fracture:   Kurchi – granular

                             Picrorrhiza- tough

Microscopical method:

Ø   To identify unorganized drug by their known histological characters

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

Ø   Stains can be used to distinguish cellular structure

              - Phloroglucinol and con HCl -  Lignin (Pink)

               - Ruthenium red – mucilage (Pink)

Histological studies – thin section of drugs

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

       Eg:   Senna – Paracytic stomata

                Vasaka – Diacytic stomata

                Nuxvomica – lignified unicellular trichomes

                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/E+S                        S.I =  Stomatal index

                                                                                     S = No of stomata

                                                                                     E = No of epidermal cells in the same unit area          

Palisade ratio :  Average number of palisade cells beneath each epidermal cells

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

Physico chemical method:

               -  Moisture content

                -  Viscocity

                -  Melting point

                -  Solubility

                -  Optical rotation

                -  Refractive index

                 -  Ash content

                  - Extractive value

                  - Volatile oil content

Spectroscopic method:

Ø    Infrared spectroscopy

Ø   Electron spectroscopy for chemical analysis

Ø   Atomic absorption Spectroscopy

Ø   X Ray diffraction analysis

Ø   X-Ray fluorescence analysis

Chromatographic method:




Ø   Gas Chromatography


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