Introduction to Pharmacognosy PDF

# Introduction to Pharmacognosy ## 1- Definition of Botany: Botany is the scientific study of plant and life. Plants are classified as: - **Nutritional:** Rice, Potato - **Ornamental:** Lavender, Jasmine - **Economical:** Cotton, Linum - **Medicinal:** Mentha, Anise ## What are Medicinal Plants...

# Introduction to Pharmacognosy ## 1- Definition of Botany: Botany is the scientific study of plant and life. Plants are classified as: - **Nutritional:** Rice, Potato - **Ornamental:** Lavender, Jasmine - **Economical:** Cotton, Linum - **Medicinal:** Mentha, Anise ## What are Medicinal Plants? Medicinal plants are plants that have a therapeutic or curative effect. Medicinal plants can also be called: herbal medicinal plants, herbal remedies, herbal drugs, or herbs. ## 2- Pharmacognosy: **Definition:** It means the study of natural substances, mainly plants, that have medicinal uses. The word "Pharmacognosy" is derived from the Greek: - Pharmacon = a drug, - Gnosis = to acquire knowledge. So, Pharmacognosy means the entire knowledge of drugs. Therefore, Pharmacognosy studies the scientific basis for the use of plants in pharmacology. ## 3- Crude (raw) drug: The plant or animal material before it is subjected to extensive processing or modification. Crude drugs are used as therapeutic agents (of medicinal use). Crude drugs are derived from: plant, animal, or mineral origins. ### Types of Crude drugs: - **Entire plant or animal:** e.g. Mentha herb, Cantharidis insect - **Entire organ:** e.g. Senna leaves, Clove buds, Thyroid gland - **Unorganized drugs:** e.g. Opium latex, Aloe juice, Acacia gum - **Mineral:** e.g. Chalk, Kaolin, Talc, Sulphur ## 4- Classification of Medicinal plants: Medicinal plants (drugs) are classified in different ways to make their study easy. Each of these ways has advantages and disadvantages. ### Classification Methods: - Alphabetical - Taxonomical - Morphological - Chemical - Pharmacological ## Classification methods include the following: ### A- Alphabetical: (According to Latin or English names) This type of classification is employed for dictionaries, pharmacopoeias ............etc. ### B- Taxonomical: Medicinal plants (drugs) are arranged based on an accepted system of botanical classification; they can be classified in classes, orders, families, genera, and species. ### C- Morphological: - **Organized drugs:** Medicinal plants are divided according to organs such as leaves, flowers, herbs, roots, fruits, & seeds. - **Unorganized drugs:** include plant products e.g., dried latex, exudates, gums, resins, oils, waxes... etc. ### D- Chemical: Medicinal plants (drugs) are arranged according to the main active constituents that the plants contain, e.g. alkaloids, glycosides, tannins, volatile oils. ### E- Pharmacological or Therapeutical: The herbal drugs are classified according to their therapeutic effects. **Example:** Drugs affecting GIT (gastrointestinal tract), heart, kidney, nervous system, etc. ## 5- Origin of drugs: ### A- Biological origin Biological origin or source of a drug is the plant or animal yielding it. Indicates the name of plant & family from which the drug is obtained. The **binomial system** for plants naming was devised by **Linnaeus (a Swedish scientist)** who gave each plant a name formed of two words. * The first word indicates the **Genus** name and is written with the first letter capital. * The second word indicates the **species** name and is written with the first letter small. * Both words must be either underlined or written in italics. **Example:** * **Atropa belladonna Fam. Solanaceae** Sometimes, the **Genus** name may be chosen to indicate a special meaning. **Example for Genus:** * **Glycyrrhiza glabra** → (from glucos=sweet, riza=root) Also, the species name may be chosen to indicate a special meaning or some striking characteristics of the plant. | Character | Hyoscyamus muticus(short) | |---|---| | Color | Piper nigrum(black) | | Aroma | Myristica fragrance (nice odor) | | Source | Cannabis indica(from india) | | Activity | Papaver somniferum (induce sleep) | | Special | Allium sativum(cultivated) | ### B- Commercial origin ### C- Geographical origin * **Habitat:** is the region in which the plant grows. * **Indigenous = Natural habitat:** → plants growing in their native countries. * **Exotic = acclimatized:** → plants growing in a country other than their native home. The climate (temp., wind, rainfall, light) affects the active constituents. Thus, the active constituents are greatly affected by the region in which the plant grows. | | | |---|---| | Climate effect | e.g. Cannabis sativa grown in | | | India and other subtropical countries | | | Contain the active constituents (resin, cannabinol..), | | | Italy and cold countries | | | free from the active constituents, for production of fibers and seeds | | | indigenous plant | | | When the plant is grown in its native country | | | acclimatized plant | ## 6- Official & Unofficial drugs - **Official drugs:** are the drugs listed in a book, recognized by a government such as the Egyptian Pharmacopeia. - **Unofficial drugs:** are the drugs not listed in a book recognized by a government. **The Pharmacopoeia** It is a governmental book that contains a listing of all official drugs with their effects & directions for their use. A drug that is not listed in the pharmacopoeia is said to be unofficial. ## Production of Medicinal plants The crude drug, which reaches the pharmaceutical manufacturing line, must pass through various stages. All these steps influence the nature & amount of active constituents present. These stages are: - I. Environmental conditions - II. Collection - III. Drying & Packing - IV. Preservation and protection (Storage) ### I. Environmental conditions Plant growth, development, as well as the nature & amount of active constituents, are affected by many environmental conditions such as: - Temperature, - Water - Light - Altitude - Soil - Plant nutrients - Plant Growth regulators #### 1. Temperature Each plant has its own **optimum temperature** that is essential for its growth. According to this optimum temperature, plants are classified into tropical, subtropical, and cold region plants. #### 2. Water * Water is an important factor for plant growth. * The amount of rainfall & degree of humidity regulates the availability of water to the plant. #### 3. Light * Light is an essential factor for plant growth. * Plants vary in both the amount & intensity of light, which they can tolerate. **Why light is essential for plants?** - Plants need light to perform photosynthesis. - Light influences the quantity of active constituents (glycosides, alkaloids) produced by the plant. E.g. Belladonna gives a higher percentage of alkaloids in full sunshine rather than it does in shade. - Light affects the flowering of plants. #### 4. Altitude * Altitude is the height of plant in relation to sea level or ground level. * Altitude influences the temperature & affects the formation of constituents. **E.g., Cinchona,** that grows at high levels, produces alkaloids, while at lower levels, the plant grows well, but it doesn't produce alkaloids. #### 5. Soil A soil is a heterogeneous mixture of organic particles, living organisms, and minerals. Different plants vary in their soil and nutritive requirements. Three important basic characteristics of soils are their physical, chemical, and microbiological properties. According to particle size, soil ranges from clay to sand to gravel. Particle size is one factor affecting water-holding capacity. * **Water capacity:** is the amount of water that remains in soil after any excess has drained away. #### 6. Plant nutrients All nutritive requirements of plants, starting from seed germination to maturity, are commonly supplied by the soil. Nutrients commonly supplied by the soil are classified into four types: - A- Main nutrients or macro elements: N, P, K * These main elements are needed in large amounts. * Deficiency of N produces Yellowing (Chlorosis). * Deficiency of P causes reduction of the plant size, decreasing active constituents * Deficiency of K decreases carbohydrate synthesis. - B- Active elements: Ca, Mg, S * These elements are not to be added to the soil as their amounts found in the seed coat are sufficient. * Plants need little amount of these elements for their growth. - C- Microelements: Cu, Mn, Zn, Fe, Co, * These are elements that are needed in very small amounts. Excess of them is toxic to the plants. - D- Inactive elements: Na, Al, Si, I * These inactive elements are only required by certain plants, not all plants. #### 7. Plant Growth Regulators (Plant hormones) The growth and development of plants is regulated by several chemical substances which together exert a complex interaction to meet the needs of the plant. Five groups of plant growth regulators are well known, they include: - A- Growth stimulators * i. Auxins * ii. Gibberellins (GA) * iii. Cytokinins - B- Growth Inhibitors: * iv. Abscisic acid * v. Ethylene gas #### A. Growth stimulators - **i. Auxins:** These are growth promoting substances, which were found to possess properties like indole-3-acetic acid (IAA), which is considered as the major auxin of plants, IAA is found in actively growing tissues that regulates the growth. Synthetic auxins include indole-3-butyric acid, and naphthalene-1-acetic acid (NAA). **Typical effects of auxins:** - Auxins stimulates the cell growth (cell elongation) i.e. stem length. - They are responsible for formation of secondary metabolites (for seedling and young plant of Mentha piperita, when treated with naphthalene acetic acid, increased the yield of oil by 30-50%. - They can be used as herbicide, when present in high concentrations. - **ii- Gibberellins:** They are synthesized in leaves and have the following effects: * Gibberellins stimulate the flowering stages, before the flowering dates. * They increase the length of the stem. * They increase the production of secondary metabolites e.g. oils & glycosides. - **iii-Cytokinins:** It is the cell division hormone. * Cytokinins stimulate mitosis & cell division. * They delay the plant's aging process. #### B. Growth inhibitors: Natural growth inhibitors are present in plants; they affect bud and seed germination and development of dormancy. (The state in which the plant is alive, but not actively growing). - **i. Abscisic acid:** It induces seed dormancy and inhibits shoot growth. - **ii. Ethylene gas:** It is the only gaseous hormone affecting plants evolved by stored apples and inhibited the growth of potato shoots evolved with them. ## II. Collection of Crude drugs * The qualitative and quantitative composition of plants may change during the growing season. * To ensure the maximum quality in crude drugs, it is important that the plants which produce them are collected in the right season and at the appropriate stage of their development cycle`. * Although the active principles of the different plants may be distributed in several or in all parts of the plant, they are more concentrated in certain organs, and these organs are usually collected as commercial drug`. **Drugs can be collected from wild or cultivated plants.** **Drugs collected from wild plants have the following advantages:** * Cheap source. * Plants grow in their native habitat. * Plants contain active constituents of best quality. * Plants contain higher percentage of active constituents. **Disadvantages of cultivation:** * High cost of production (high cost of labours and land). * Medicinal plants need a particular environment, which can't be afforded in cultivation. ### Comparison between Cultivated & Wild plants: | | Cultivated Plants | Wild Plants | |---------------------------|-------------------------------------------------------|----------------------------------------------------------| | Area of cultivation | Cultivated plants provide a large area of medicinal plants in an accessible area. | Wild plants are scattered in unlimited areas (deserts, forests, or seas) that may be difficult to reach and be collected. | | Supply of raw materials | Cultivated plants provide a regular and sufficient supply to meet the market demands. | Collection of wild plants may lead to deficiency in certain medicinal plants. | | Collection techniques | All operations including collection, drying and storage are carried out by skilled people; also it ensures the purity of the product. | Unskilled people carry out collection which may lead to collection of wrong plant at wrong time & the plant may be liable for adulteration mixed with other plant. | | Proximity to factory | All steps are done near a pharmaceutical factory so the plant could be taken directly from the field to the factory.| Transportation to the factory may take a long journey that requires effort, cost and may lead to loss of active constituent due to deterioration by storage and careless handling.| ### Factors affecting collection: #### A. Time ##### 1. Time of the year (season): - **E.g1. Rhubarb:** - In winter: there are no anthraquinones. but contain only anthranols (emetics, cause gripping) - In warm weather (spring, summer): anthranols are converted by oxidation into anthraquinones (the active constituents responsible for the laxative effect). - **E.g2. Colchicum corm:** - In spring: → the active constituent → colchicine - In autumn: → the active constituent → starch ##### 2. The time of the day: - **E.g1. Digitalis leaves:** - When collected in the afternoon → high % of glycosides, - when collected at night → low % of glycosides, (hydrolysis) - **E.g2. Solanaceous leaves:** - When collected in the morning → high % of alkaloids are present. ##### B. Stage of Maturity: - **Maturity:** - Certain drugs contain the maximum amount of the active constituents at a definite stage of plant growth and must be collected at this stage. - Clove flower → collected in bud form. - Santonica flower → collected unexpanded flower head. ## III. Drying & Packing ### A- Drying of crude Drugs: Fresh organs, when collected are either used as such or dried to be used later. Why drugs are dried? **Drugs are dried for the following reasons:** - Drying aids in their preservation, to prevent the growth of microorganisms such as bacteria and fungi. - Drying fixes their constituents, to inhibit the enzymatic or hydrolytic reactions that might alter the chemical composition of the drug. - Drying facilitates the grinding into fine powder which reduces the weight to facilitate packing, transport, and storage. Drying is controlled by the nature of the material to be dried and the desired appearance of the finished product. **There are two main points to be considered for successful drying:** 1. Controlling of temperature 2. Regulating of air flow or ventilation. ### Methods of drying: There are two methods of drying: Natural Drying and Artificial Drying #### 1. Natural Drying: It is the use of climatic heat; depending on the weather, thus the drying is done in open air by: - A. Exposure to sun: except if the active constituents or colour are sensitive. - B. Shade drying by putting on the floor or trays in a single layer to preserve the natural colour of the drug and preserve its sensitive active constituents. #### 2. Artificial Drying: Artificial Drying is necessary in tropical countries, where humidity is high. | Point of comparison | Natural Drying | Artificia Drying | |---|---|---| | Advantage(s) | Cheap | -Rapid -It is done at controlled temperature -It stops enzymatic hydrolysis | | Disadvantage(s) | It takes long time Not suitable in countries with high humidity | more expensive than natural drying | ### Methods of Artificial Drying: - **a) Chemical drying:** The drug is placed in a desiccator with a dehydrating agent (quick lime) to form dry atmosphere. - **b) Physical drying:** It involves the use of elevated temperature and/ or reduced pressure (vacuum). It may be applied by: - i. Direct heat. - ii. Drying chamber. - iii. Drying oven. - iv. Freeze drying (Lyophilization). - v. Pneumatic High Speed Drying (Flash Drying) . #### Physical Drying may be applied by: - **i. Direct heat:** Drying is done by open fires or stoves, they are used for drugs with heat-stable active constituents. - **Disadvantage:** Temperature is uncontrolled. - **ii. Drying chamber:** It is a small chamber with shelves, door, windows and hot water pipes. There must be a space of at least 15 cm between superimposed trays, so as air can circulate freely. - **Advantages:** - Temperature is controlled. - Drugs are not affected by any weather change: - **iii. Drying oven:** It is a small cabinet having a source of heat device for circulating air. When evacuated (vacuum oven) it is rapidly and efficiently performed drying at lower temperature (advantage). - **iv. Freeze drying: (Lyophilization)** The drug is subjected to high vacuum before & after freezing until completely dry`. Very low temperature and high vacuum are used. - **Advantage:** It retains the colour & texture of the product. It is used for biological fluids, & drugs containing unstable constituents. - **v. Pneumatic High Speed Drying (Flash Drying)** The drug is dried by exposure to high temperature 800°C for a fraction of a second under reduced pressure. It is used for sensitive drugs. ### Changes in Drugs during and after drying: 1. **Size and weight:** reduction in size and weight occur due to loss of water. 2. **Shape and appearance:** Some drugs shrivel and shrink when dried, and the surface gets wrinkled and reticulated. The inner surface of most barks gets cured and becomes rolled as the inner tissues are soft and outer ones are hard. 3. **Colour:** Generally, on drying the drug becomes darker in colour, but in some cases a total change may occur. E.g., Tea leaves: dark, black (after drying), green (rapid drying): - **Reason:** Presence of an oxidase enzyme (phlobatannins are characterized by phlobaphene, black). 4. **Odour:** Drying may change the natural odour. - **E.g1. Vanilla pods:** are odourless when fresh, while they become fragrant, pleasant when dry due to formation of vanillin. - **E.g2. Digitalis and Hyoscyamus:** lose their undesirable odour. 5. **Constituents:** Generally no change in constituents on drying. Sometimes change occur: - **a. E.g., Fresh Vanilla pods contain:** - Glucovanillin glycoside: on drying →It is hydrolysed → vanillin + Sugar - **b. Glucovanillic alcohol: on drying →It is oxidized to → vanillin.** 6. **Taste:** Taste of the drug may be altered. E.g., Gentian is very bitter when fresh, → on drying: bitter taste → sweet & pleasant. ## IV. Preservation and protection: Storage represents the last step in the handling of crude drugs before being used, and it is the most important stage. Proper storage and preservation are important factors → lead to high degree of quality of drugs. Drugs usually deteriorate either slowly or rapidly during storage with few exceptions: **E.g., Cascara and Frangula, they should only be used after certain period of storage.** **Store 4 Years** The general undesirable changes which may occur on storage are: - Drugs containing volatile oils gradually lose their aroma. - Ergot acquires disagreeable aroma, - Drugs containing fixed oil (fatty seeds) may be rancid. Certain pharmacopeias give well, clear instructions concerning time of storage, after which drugs shouldn't be used. ### Crude drugs must be stored: 1. In well close containers (air-tight). 2. Away from light (amber-glass containers), moisture and dust. 3. At low temperature. 4. Away from insects. ### Improper methods of storage: The principal factors responsible for deterioration of drugs are: 1. Physicochemical factors → moisture (humidity), heat, air 2. Biological factors → fungi, bacteria, insects and rodents. #### 1. Physicochemical factors - a. Moisture may cause: - Hydrolysis of active constituents by enzymes. - Growth and nourishment of bacteria and fungi. - **To overcome the effect of hydrolysis stabilization of the drug is carried by:** - Enclosing dehydrating agents as lime or calcium chloride in the container of the stored drug. - Destroying enzymes by immersing the fresh drug in alcohol. - b. Light - Photochemical reactions may occur that affect delicate drugs. - Digitalis leaves lose the activity more rapidly in sun light. - To avoid the effects of light, drugs should be stored in darkness, using opaque or amber coloured glass containers. - c. Temperature - A slight raise in temperature will activate the enzymatic action. - Drugs affected with the rise in temperature are those containing oil such as clove and chamomile. - d. Air - Oxygen of air has an oxidation effect on the active constituents of drugs leading to lowering the quality of products. - Oxidative changes are sometimes required to produce desired constituents as in case of Frangula bark. ## Biological factors: ### A. Bacteria and fungi - Sufficient moisture content is essential for bacteria or fungal infestation. - Bacteria or fungal infestation may change the physical properties of the drug as colour and texture. ### B. Insects - The presence of fungi is indicated by their hyphae. (orange) - Insects could be controlled by one of the following methods: - **i. Heat treatment:** It is done by exposing the crude drugs to temperature 60-65°C which can kill insects as well as their eggs. (Should not be used for thermolabile or volatile constituents) - **ii. Fumigation:** Drugs are subjected to poisonous gas (HCN) or liquid vapor in a closed room. - **Drawback:** This method kills the insects but not their eggs. - **iii. Liming:** Drugs are covered by a coat of lime before storage which block the respiratory system of insects and larvae (to prevent insect-attack), e.g., Nutmeg, Ginger. - **iv. Low temperature storage (refrigeration or freezing):** It is the most suitable method; it kills all stages of insects; it does not affect the active constituents. ### C. Spoilage by rodents: (rats & mice) - The presence of filth of rodents (hairs, excreta) can cause the spoilage of drugs, they must be rejected. - A.N.T.U. alpha naphthyl thiourea, is used to eliminate rats and mice (rodenticide). N.B. Some drugs are sterilized before storage. ## Oh Dryg Salase-Adulteration of crude drugs Adulteration is the debasement of any article. Debasement is the process of spoiling something or reducing its value by combining it with another material. - Adulteration may occur when the drug is unavailable or when the price of drug is high. - The adulterant must be some material, which is cheap and available in huge amount ### Adulteration involves: 1) Sophistication (True adulteration) The addition of an inferior material to any article with intention to deceive the consumer. **E.g.** Addition of wheat flour (to add volume), capsicum (to restore pungency) & curcuma (to maintain the colour) to powdered ginger. | | | |---|---| | Wheat flour | Bulk | | Capsicum | Pungent taste | | Curcuma | Restore color | | | Adulte rated Ginger | 2) Substitution An entirely different article is used instead of the required drug. Substitution is different from sophistication, as none of the true article is present. ### Substitution is carried out in different ways: - **a. Substitution with inferior quality** It is the use of morphologically resemble, different inferior commercial varieties (may or may not have any chemical or therapeutic potential as that of the original drugs). An entirely lower quality e.g. Arabian Senna is used to adulterate genuine Senna. - **b. Substitution by exhausted drugs** - Exhausted drug: The plant material is mixed with drug that is devoid of any medicinally active constituents as they are already extracted out. - Volatile oil containing drugs: - E.g. Clove from which part of the oil has been removed by distillation. (Partially exhausted). - **c. Substitution by an inferior, cheap morphologically similar but different substances** - Substitution with a drug having no relation to the genuine drugs, may or may not have any therapeutic or chemical components. - E.g., 1: use of Cotton seed oils instead of Olive oil. - E.g.,2: use of Scopolia leaves instead of belladonna leaves. 3) Admixture The addition of an article to another through accident, ignorance or carelessness. If the addition is intended, it is sophistication. ### Admixture may occur through: - a. Faulty collection as collecting the drug not at the proper time, - E.g. Collecting Solanaceous leaves in summer. - b. Faulty collection of other parts of the same plants by mistake - E.g. stalks, aerial parts with leaf drugs. - c. Collection from other plants by mistake or ignorance of collectors. 4) Deterioration An impairment of the quality of a drug by destruction of active constituents by physical process as distillation, extraction, aging, moisture, heat, insect or other means. - E.g.1 Coffee which lost caffeine through over-roasting. - E.g.2 Powdered Squill hardened through absorption of moisture. ### Deterioration is carried out in different ways: - a) Spoilage: - A special form of deterioration in which the quality of a drug is impaired or destroyed by the action of bacteria or fungi, making it unsuitable for consumption. - b) Inferiority: - Inferiority refers to sub-standard drug. It is any drug not conforming standards, means containing fewer amounts of active constituents. - E.g.,1 the dried seeds of Nux vomica containing less than 1.15% strychnine. - c) Using synthetic drugs - Certain synthetic articles are added to fortify the drug e.g. as addition of Citral to lemon oils. - **Improves its effectiveness stability or nutritional value** ### Detection of adulterants: microchemical test = under the microscope It involves the identification of the adulterant and determination of the quality of the drug. Several methods are used such as: - 1. Macro and micro morphology. - 2. Solubility. - 3. Qualitative tests. Identification of active constituent - 4. Quantitative tests. Concentration of active constituent - 5. Yield to solvents. - 6. Pharmacopeial constants (Total ash, water soluble & insoluble ash, acid soluble & insoluble ash). - 7. Comparison with an authentic sample of the drug. ## Primary & Secondary metabolite all drugs have, protein lip, fats, carb ### Primary metabolites 1. Primary metabolites are essential for life process. (Growth & division of the cells) 2. These are produced continuously during the growth phase and are involved in primary metabolic processes such as respiration and photosynthesis, etc. 3. Produced in large quantities, so their extraction is easy. 4. Same in all plants. 5. Proteins, carbohydrates and lipids are the main primary metabolites. ### Secondary metabolites 1. These are non-essential and act as defense mechanisms and to attract pollinators. 2. These compounds don't have continuous production. However, they are produced during non-growth phases of cells. 3. Produced in small quantities, so their extraction is difficult. 4. Different (unique) in certain plants. 5. Alkaloids, glycosides, fixed oils, volatile oils, and tannins etc. ## Cell Content * Starch is tested by lodine test (microchemical test); it gives bluish violet color. | | Potato | Wheat | Maize | Rice | |---|---|---|---|---| | Size | Largest | Large | Medium | Small | | Shape | Oval | Lenticular or round | Polyhedral | Polyhedral | | Hilum | Small eccentric | Small centric | Stellate centric | Absent | | Striation | Clear | Very fine in large particles | Absent | Absent | | Aggregation | Simple & compound | Simple & compound | Simple & compound | Simple & compound | | Drawing | | | | | ## 1. Protein ### A. Shapes of protein: 1. **Aleurone grains:** - - The crystalloid (angular shape). - - The globoid (rounded shape). Each aleurone grain has a bounding membrane enclosing the globular body, the crystalloid, and a smaller rounded one, the globoid. 2. **Amorphous protein:** with no definite shape. ### B. Chemical test for proteins: - Protein is tested by Picric acid; it gives yellow color. ## Crystals: ### A. Calcium oxalate crystals: It is considered one of the most important cell contents through which we can differentiate between different drugs, because they have different shapes, they can be: - - Clusters. - - Styloid (prisms & twin prisms). - - Raphides (Needles). ### B. Calcium carbonate (Cystolith): Calcium carbonate could be detected by dil. HCL, it gives effervescence.