Lecture 11 (Introduction to Pharmacognosy-II) - Mansoura National University - 2024/2025 - PDF

Medicinal plants 2024/2025 Lecture 11 Dr. Amal F. Soliman Associate Professors of Pharmacognosy  ‫أجزاء المنهج‬ ❑ Anatomy (Lectures 1, 2, 3, 4, 5,6) ❑ Dusting powders (Lecture 7) ❑ Taxonomy (Lecture 9) ❑ Physiology (Lecture 9) ❑ Introduction to Pharmacognosy...

Medicinal plants 2024/2025 Lecture 11 Dr. Amal F. Soliman Associate Professors of Pharmacognosy  ‫أجزاء المنهج‬ ❑ Anatomy (Lectures 1, 2, 3, 4, 5,6) ❑ Dusting powders (Lecture 7) ❑ Taxonomy (Lecture 9) ❑ Physiology (Lecture 9) ❑ Introduction to Pharmacognosy (Lectures 10, 11)  Adulteration ‫الغش‬ ❑ Adulteration occurs when the drug is scarce drug or expensive. It occurs intentionally or due to ignorance and carelessness. ❑ The adulterate is usually a cheap material and is available in large amount. ❑ Adulteration with worthless material will lower the quality and the efficacy of the drug. Adulteration with poisonous material will affect also, the safety of the drug. So, the adulteration should be identified.  Types of Adulteration 1. Sophistication (Drug+ Adulterant) (true adulteration) ▪ It is the addition of an inferior material to the drug intentionally. ▪ Examples: The addition of saw dust to ginger powder or hazelnut shell to cinnamon or rhubarb powder.  2. Substitution (Adulterant only) ▪ It is the use of an entirely different article in place of the true drug. (i.e., none of the true drug is present). ▪ Types of substitution: Substitution by an inferior variety of the drug, (dog senna instead of the true senna). Substitution by a morphologically similar but completely different drug, (Phytolacca decandra leaves for Atropa belladonna leaves). Substitution of ginger with mixture of maize starch to give bulk of powder with enough capsicum to restore the pungency and curcuma to restore the color. Substitution by an exhausted drug. The residue remains very similar to the original material, so used as substituents (Exhausted tea, exhausted liquorice). Atropa belladonna Phytolacca decandra  3. Admixture ▪ The addition of one article to another through accident, ignorance or carelessness. Admixture may occur through faulty collection. ▪ Collection of another part of the same plant, e.g., stems, stalks and aerial parts with leaf drugs. ▪ Collection of other plants by mistake or ignorance of collectors.  4. Inferiority ▪ This means the use of a substandard drug i.e., inferior to the true one (containing less amounts of active constituents). ▪ It may occur as a result of collecting the drug in the wrong time. 5. Deterioration (Spoilage) ▪ In this type, an impairment of the quality of the drug occurs as a result of either aging or improper storage or destruction by fungi or insects. ▪ All these factors results in lowering or destruction of the active constituents of the drug.  6. Addition of worthless heavy material ▪ Stones were found in the center of Liquorice bales. ▪ Pieces of lead shots were found in opium.  Evaluation of crude drugs ▪ Evaluation of a drug means its identification and determination of its quality and purity. ▪ We use several methods: 1. Organoleptic methods 2. Microscopical methods 3. Biological methods 4. Chemical methods 5. Physical methods 6. Chromatographic methods 1. Organoleptic methods ▪ Organoleptic refers to evaluation of drugs by means of the organs of sense. ▪ This includes the macroscopic appearance of the drug (shape, size, color, external marking, and fracture), taste, and the feel of the drug to touch. 2. Microscopic methods ▪ The microscopic examination of the entire and powdered drugs is essential for their investigation and detection of adulteration. ▪ We can use different mounting media, one can study the different elements and the cell contents, e.g. ✓ Water: to examine starch. ✓ Phloroglucinol-hydrochloric acid: to examine lignified elements. ✓ Chloral hydrate: to examine calcium oxalate, trichomes, epidermal cell and others. 3. Biological methods ▪ The pharmacological activity of certain drugs (e.g., antibiotics, hormones, vaccines, and some other drugs) has been applied to their evaluation and standardization. ▪ Assays on living animals or on organs often indicates the strength of the drug or its preparation. 4. Chemical methods ▪ Chemical tests for the chief active constituents are employed to identify certain crude drugs. ▪ Examples are the color reaction of alkaloids with alkaloid reagents and the reducing effect of sugars with the Molisch's, Fehling, and Barfoed's reagents. 5. Physical methods ▪ Physical constants such as solubility, specific gravity, optical rotation, refractive index and melting point are extensively determined for the active principles of drugs. ▪ Examples: ✓ In case of clove and galls when sink in water, they are of good quality. ✓ UV examination is applied in case of certain drugs such as Rhubarb (to detect any adulteration with the blue fluorescent (Rhapontic rhubarb) and in case of some alkaloids such as quinine (blue), and emetine (orange). ‫القرنفل‬ 6. Chromatographic methods ▪ Chromatography refers to a number of sensitive techniques for the separation & identification of drugs. ▪ For each drug extract, there is a chromatographic fingerprint that can be used for its identification by comparing with authentic one. HPLC Chromatogram TLC  Chemistry of Crude drugs I- Food storage substances ▪ Starch ▪ Protein ▪ Fixed oils and Fats II- By-products of metabolism 1. Crystals (Oxalate, Carbonate, Silica) 2. Gum, Mucilage and Pectin 3. Resin and Resin combinations 4. Tannins 5. Volatile oils 6. Alkaloids 7. Glycosides I- Food storage substances ▪ Starch Gives blue color with Iodine solution. Stained red with Millon reagent, yellowish brown with iodine ▪ Protein solution and yellow with picric acid. ▪ Fixed oils and Fats ✓ They are greasy and non-volatile. ✓ They give permanent stain on paper. ✓ They are hydrolyzed by alkali giving soaps and glycerin. ✓ They are stained red with Sudan III and Alkanna tincture. II- By-products of metabolism 1. Crystals (Oxalate, Carbonate, Silica) a- Calcium oxalate ▪ It is a very common cell content in plant kingdom. ▪ It is formed in the cell as a product of metabolism; as a result of the reaction of the calcium salt absorbed from the soil and oxalic acid produced in the plant from the metabolic process. ▪ It crystallizes when the cell sap is super saturated with the salt in different shapes and sizes characteristic for each plant. Forms of Ca Oxalate crystals Prisms Clusters Acicular or Needle Micro crystals or shaped crystals sandy crystals b- Calcium carbonate ▪ They are found embedded in the cell walls, or in outgrowths of it e.g., hairs (Cystolith) as in leaves of Cannabis sativa. ▪ Calcium carbonate can be identified by dissolving in dilute acids with effervescence. c- Silica ▪ Silica forms the skeleton of diatoms (kieselguhr) and occur in the cell walls of some plants or as masses in the interior of the cells e.g., sclerenchymatous layer of cardamom seed. N.B. ✓Diatoms are single-celled organisms. ✓The skeleton of a diatom, is made of very pure silica coated with a layer of organic material. ▪ Silica is insoluble in all acids except hydrofluoric acid. 2. Gum, Mucilage and Pectin ▪ These are polysaccharide complexes formed from sugar and uronic acid units. ▪ Mucilage are two types: ✓ Pectose type (e.g., Senna leaves). It is stained red with Rhuthenium red. ✓ Callose type (e.g., Fenugreek seeds). It is stained red with Coralline soda. Gums Corchorus olitorius ‫امللوخية‬ 3. Resin and Resin combinations ▪ Resins are formed in plants as amorphous masses of different chemical structure. ▪ They may be secreted into secretory ducts or cavities. Rosin (Colophony) Frankincense (Olibanum) ‫قلفونيه‬ ‫اللبان ادلكر‬ 4. Tannins ▪ They are phenolic substances. ▪ Tannins have astringent effect. ▪ There are classified into two main groups: ✓ Pyrogallol tannins (Hydrolysable tannins) gives bluish black color with FeCl3. ✓ Catechol tannins (Condensed tannins) gives greenish black color with FeCl3. 5. Volatile oils ▪ Chemically: they are mixtures of hydrocarbons and oxygenated compounds derived from these hydrocarbons. ▪ Give temporary stain on filter paper. ▪ They give red color with Sudan III and Alkanna tincture. ▪ Secreted in: ✓ Oil cells (Cinnamon). ✓ Oil glands (Eucalyptus, Clove). ✓ Glandular trichomes (Mentha). ✓ Secretory ducts (Anise, Cumin). ▪ Some are medicinally important: ✓ Buchu oil (Urinary tract infections). ✓ Eucalyptus oil (antirheumatic). 6. Alkaloids ▪ Basic nitrogenous compounds of natural origin. ▪ Having different structural nuclei. ▪ Mostly bitter in taste. ▪ Mostly, Alkaloids gives with Mayer’s Reagent, a yellowish white ppt and gives with Dragendorff’s Reagent, an orange-red color. ▪ They have variable therapeutic uses, e.g.: ✓ Quinine (Anti-malarial) ✓ Morphine (Analgesic, pain killer) Positive Dragendorff’s test 7. Glycosides ▪ Natural organic compounds composed of sugar part (glycone) and non-sugar part (aglycone). ▪ The aglycones of the glycosides differ in their chemical structure. Accordingly, glycosides are classified to several groups: ✓ Flavonoid glycosides. ✓ Anthraquinone glycosides ✓ Cardiac glycosides ✓ Saponin glycosides ✓ Cyanogenic glycosides ‫جشرة الصفصاف‬ From these types of adulteration (Sophistication, Substitution, Admixture, Inferiority, Deterioration, Addition of worthless heavy material), determine which type of adulteration exists in the following sentences. Each word can be used more than one time or not used at all: ✓ Addition of sawdust to ginger powder. ✓ The use of exhausted Liquorice instead of genuine Liquorice. ✓ Use of Phytolacca decandra leaves instead of Atropa belladonna leaves. ✓ Collection of Clove stalks with Clove buds by ignorance. ✓ Use of a mixture of maize starch with capsicum and curcuma instead of ginger. ✓ Addition of stones to Liquorice bales accidently. ✓ Addition of hazelnut shells to Cinnamon powder. ❑ How can you differentiate between each pair of the following items: ✓ Pyrogallol tannins and catechol tannins ✓ Volatile oils and fixed oils ✓ Pectose mucilage and callose mucilage ❑ How can you: ✓ Check the presence of alkaloids in a plant sample. ✓ Control the insects and ensure its destruction during and before storage. ✓ Ensure the good quality of Clove using a simple test. ✓ Check the presence of lignified elements in a plant sample. ✓ Ensure the stabilization of crude drugs against moisture. ✓ Check the presence of starch in a plant sample. We hope you enjoyed studying this course!