Medicinal Plants (PPC101) Lecture 4 PDF

Medicinal Plants (PPC101) Reda F. A. Abdelhameed, PhD gu.edu.eg Lecture 4 Adulteration of Herbal Drugs  Introduction The term 'adulteration' of an article covers a number of conditions, which may...

Medicinal Plants (PPC101) Reda F. A. Abdelhameed, PhD gu.edu.eg Lecture 4 Adulteration of Herbal Drugs  Introduction The term 'adulteration' of an article covers a number of conditions, which may be intended or by accident, usually in crude drugs, this practice includes substitution of the original crude drugs partially or fully with other substances which is either free from or inferior in therapeutic and chemical properties. Inferiority is a natural substandard condition (e.g. where a crop is taken whose natural constituent is below the minimum standard for that particular drug) which can be avoided by more careful selection of the plant material.  Spoilage is a substandard condition produced by microbial or other pest infestation, it can be avoided by careful attention to the drying, and storage conditions. Deterioration is an impairment of the quality or value of an article due to destruction of valuable constituents by bad treatment or aging or to the deliberate extraction of the constituents and the sale of the residue as the original drugs. Admixture is the addition of one article to another through accident, ignorance or carelessness e.g. inclusion of soil on an underground organ or the co- collection of two similar species.  Sophistication is the deliberate addition of spurious or inferior material with intent to defraud; such materials are carefully produced and may appear at first sight to be genuine e.g. powder ginger may be diluted with starch with addition of little coloring material to give the correct shade of yellow color. )Partial) Substitution is the addition of an entirely different article in place of that which is required e.g. supply of cheap cottonseed oil in place of olive oil. (Total)  TYPES OF ADULTERATION OR SUBSTITUTION OF HERBAL DRUGS Different methods used for adulteration may be grouped as follows: 1. Substitution with Inferior Commercial Varieties Due to morphological resemblance to the authentic drugs, different inferior commercial varieties are used as adulterant which may or may not have any chemical or therapeutic potential as that original natural drug e.g. dog Senna (Cassia obovata) have been used to adulterate Senna (Cassia acutifolia) 2. Adulteration by Artificially Manufactured Substitutes To provide the general form and appearance of various drugs, some materials are artificially manufactured and are used as substitute of the original one, e.g. paraffin wax after yellow coloration substituted for bees wax. 3. Substitution by Exhausted Drugs Here the same plant material is mixed which is having no active medicinal components as they have already been extracted out. This practice  It is most common in case of volatile oil containing materials like clove, fennel etc., where the dried exhausted material resembles the same like original drug. Sometimes when coloring matters have been extracted or removed during exhaustion, the residue is re-colored with artificial dyes as is done with saffron and red rose petals. 4. Substitution by Superficially Similar but Cheaper Natural Substances Usually here the adulterated product has no relation with the genuine article, may or may not have any therapeutic or chemical component desired. e.g. Ailanthus are substituted for belladonna, senna, mint and dandelion for henbane; Indian dill with European dill or caraway etc. 5. Adulteration by Addition of Worthless Heavy Materials A large mass of stone mixed with Liquorice root, pieces of limestone are found in asafoetida and lead (Pb)shot has occurred in pieces of opium etc. 6. Addition of Synthetic Principles Sometimes to fortify inferior natural products, synthetic principles are added e.g. adding citral to oil of lemon 7. Usage of Vegetative Matter from the Same Plant This is done by mixing adventitious matters or naturally occurring with the drug in excessive amount or parts of plant other than that which constitutes the drugs. For example :stems of buchu are sometimes cut into short lengths and added to the drug (leaves).  Evaluation of drugs It means to identify the quality and purity of the drug. This is done by the following methods: 1. Organoleptic methods: By means of the organs of sense. This includes the macroscopic appearance of the drug (shape, size, color, external markings and fracture), taste and the touch of the drug. 2. Microscopic methods: By microscopic examination of the histology of powdered drugs. By detecting the key elements as starch, hairs, ca ox crystals, …. 3. Biological methods: By checking the pharmacological activity of certain drugs. Assays on living animals can indicate the strength of the drug.  Evaluation of drugs 4. Chemical methods: Drugs are usually exposed to strict chemical tests for their identification. Examples are the color reaction of alkaloids with the alkaloid reagents and the reducing effect of sugars with the Molisch’s and Fehling. 5. Physical methods: Physical contents such as solubility, optical rotation, refractive index, melting point. Occasionally, specific gravity is of interest, as in case of Clove and Galls, which are considered of good quality if they sink in water. 6. Chromatographic methods: Chromatography refers to a number of sensitive techniques for the separation and identification of drugs (TLC, CL, GC, HPLC,…).  CELL CONTENTS Can be identified microscopically, chemically and physically. (1) Primary Metabolites (Food Storage Products): Food reserve products [carbohydrates, proteins and lipids] (2) Secondary Metabolites: By-products of metabolism as [alkaloids, glycosides, volatile oils, tannins,……]  Primary Metabolites (1) Carbohydrates (C, H and O) A- Starches: – Occur in plants as granules. – Consist mainly of amylose (20%), amylopectin (80%) [it is insoluble in water and gives a blue colour with iodine]. Amylose Amylopectin Uses of starch: 1- In itching (demulcent) 2- Antidote for iodine poisoning. 3- Lubricant for surgeon gloves 4- Tablet disintegrate 5- Suspending agent for barium meals. 6- Starting product for preparation of dextrins. 2- PROTEINS Are nitrogenous organic compounds. They are macromolecules, polymers of L-amino acids. Tests for proteins: Millon’s reagent: stains proteins red on warming Stored in plants as aleurone grains. 3- Fixed oils and Fats : Occurs in various parts of the plants (especially the seeds). Chemically, they are mixtures of esters of fatty acids with glycerol. They are greasy and non-volatile at ordinary temperature. Fats and oils are lighter than water and insoluble in it. They produce a permanent stain on paper. They are hydrolyzed by aqueous alkalis giving soaps (salts of fatty acids) and glycerin. They are stained red with Sudan III  Secondary Metabolites (Byproducts of Metabolism) 1- Crystals: It is a very common cell content in the Plant Kingdom. a) Calcium oxalate: Forms of Crystals: Prism: e.g. in the crystal sheath in Senna. Cluster: e.g. in Rhubarb. Rosette e.g. in aleurone grains of the Umbelliferae. Acicular or Needle-shaped crystals: commonly occurring in bundles e.g. in Squill and Ipecacuanha. Microcrystals or Sandy crystals e.g. in Belladonna leaf  Secondary Metabolites (Byproducts of Metabolism) Calcium oxalate crystals are insoluble in water, glycerin, alcohol, chloral hydrate and caustic alkalis. They dissolve in acids without effervescence (c.f. calcium carbonate). b) Calcium carbonate: e.g. in hairs (termed cystolith), as in the leaves of Cannabis sativa. Calcium carbonate can be identified by the fact that it dissolves in dilute acids with effervescence.  Plant tissues Acc to the stage of development, Tissues are classified : I- Meristematic tissues : where the cells have the ability to divide. II- Permanent tissues : where the cells lost the ability to divide II- Permanent (Mature) Tissues: 1- Parenchyma: They are simple living tissues, having thin cellulosic walls, with intercellular spaces. 2- Collenchyma : Simple living tissue with thick cellulosic walls. in T.S. 3- Sclerenchyma (fibers and sclereides): L.S.  They are dead cells when mature, e.g sclerides or fibers  they have thick lignified secondary walls. Function: Provide mechanical support.  4-Vascular tissues : They consist of xylem and phloem. a- Xylem: consists of: Vessels, tracheids, fibers & parenchyma. Vessel elements : Transport H2O & minerals from root to other parts of the plant. Wood fibers : They are supporting elements. A: pitted tracheid, B: scalariform tracheid; C: annular vessel; D and E: spiral vessels; F: reticulate vessel; G: scalariform vessel; H: pitted vessel. A B CD E F G H b- Phloem: It is a food conducting tissue.  Epidermis: It is the outer layer of plant surface and it is a complex tissue It consists of: 1- Epidermal cells 2- Stomata 3- Hairs. 1- Epidermal cells consist of one layer of cells. They have thin cellulosic walls covered with cuticle (waxy material). 2- Stomata: These are openings in the epidermis of stem and leaves. control Gas Exchange which is involved in Photosynthesis pores subsidiary cells  Types of Stomata according to the number and arrangement of the subsidiary cells: a. Diacytic. b. Paracytic. d. Anomocytic d. Anisocytic.  3- Hairs: They are either glandular or non-glandular. They have different shapes, and used for the identification of drugs. External secretory structures Glandular Hairs Non Glandular Hairs  Internal secretory structures: 1- Ducts : They may contain gums, resins, mucilage or oil, They may be: Schizogenous ,lysigenous or schizolysigenous. a.Schizogenous: where localized cell separation creates spaces; The duct is lined with epithelial cells. The cavity is smooth and regular  b. Lysigenous: The duct is formed by disintegration of cells leaving a space. The cavity is rough and irregular c. Schizolysigenous: The duct is formed by partial disintegration of cells, i.e.. some of the epithelial cells remain intact. 2- Laticifers : These are structures containing latex which are formed of a single elongated (latex cell ) cell or formed by a combination of many cells after breakdown of the separating cell walls (latex vessel), e.g. opium.  Give short note on - Importance of natural products - 1- can not be synthesized, so it is - 2-prototype - 3- inactive - 4 134 student- Group A