Herbs as raw material
Content
• Source of herbs
• Identification and authentication of herbs
Objective
At the end of this lecture, student will be able to
• Discuss the source of herbs, selection, identification and authentication of herbal materials
Herb:
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 Involvesclassical 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 TLC
Ø HPLC
Ø HPTLC
Ø Gas Chromatography
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