Fall 2024 Handout PHG 101(1) PDF

1- Definition of Botany: Botany is the scientific study of plant and plant life. Plants are classified as: 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...

1- Definition of Botany: Botany is the scientific study of plant and plant life. Plants are classified as: 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 pharmacy. 1 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. 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 2  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: i- Organized drugs: Medicinal plants are divided according to plant organs such as leaves, flowers, herbs, roots, fruits, & seeds. ii- Unorganized drugs: include plant products e.g., dried latex, extracts, 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 uses. 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 Linnus (a Swedish scientist) who gave each plant a name formed of two words. 3  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: e.g. Atropa belladonna Fam. Solanaceae Sometimes, the genus name may be chosen to indicate a special meaning. Example for a 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. 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. 4 6- Official & Unofficial drugs Official drugs: are the drugs listed in a book, recognized by the government such as the Egyptian Pharmacopeia. Unofficial drugs: are the drugs not listed in a book recognized by the government. The Pharmacopoeia It is a governmental book that contains a listing of all official drugs, along with their effects & directions for their use. A drug that is not listed in the pharmacopoeia is said to be unofficial. 5  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: 1. Temperature 2. Water 3. Light 4. Altitude 5. Soil 6. Plant nutrients 7. 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. 6 Water is important for the following reasons: a. Water is a vital factor for all biological reactions. b. Water allows the movement of minerals from the root to all plant’s parts. c. Water represents 80-90% of protoplasm, the living part of the cell. d. Water regulates the plant temperature by transpiration. 3. Light Light is an essential factor for plant growth. Plants vary in both the amount & intensity of light, which they need. Why light is essential for plants? a. Plants need light to perform photosynthesis. b. Light influences the quantity of active constituents (glycosides or alkaloids) produced by the plant. E.g. Belladonna gives a higher content of alkaloids in full sunshine rather than it does in shade. c. 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 active constituents. E.g., Cinchona, that grows at high levels, produces alkaloids, while at low levels, the plant grows well, but it doesn’t produce alkaloids. 5. Soil A soil is a heterogeneous mixture of organic particles, living organisms & 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. 7  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. 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: B- Growth Inhibitors: i. Auxins iv. Abscisic acid ii. Gibberellins (GA) v. Ethylene gas iii. Cytokinins 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). 8  Typical effects of auxins: Auxins stimulates the cell growth (cell elongation) i.e. stem length. They are responsible for formation of secondary metabolites, e.g. seedling and young plant of Mentha piperita, when treated with (NAA) naphthalene acetic acid, increased the yield of oil by 30-50%. They can be used as herbicide, when present in high concentration. ii- Gibberellins They are synthesized in leaves and have the following effects: Gibberellins stimulate the flowering stages, before the normal flowering dates. They increase the length of the stem. They increase the production of secondary metabolites e.g. volatile 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 opening, 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; it is evolved by stored apples and inhibited the growth of potato shoots enclosed with them. 9 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. 10  Comparison between Cultivated & Wild plants: Cultivated Plants Wild Plants Cultivated plants provide a large Wild plants are scattered over area of medicinal plants in an unlimited areas (deserts, forests, accessible area. or seas) that may be difficult to reach and be collected. Cultivated plants provide a Collection of wild plants may lead regular and sufficient supply to to deficiency in certain medicinal meet the market demands. plants. All operations including collection, Unskilled people carry out the drying and storage are carried out collection which may lead to the by skilled people, also it ensures collection of wrong plant at wrong the purity of the product. time & the plant may be liable to adulteration. All steps are done near a Transportation to the factory may pharmaceutical factory so the take a long journey that require plant could be taken directly from effort, cost and may lead to loss of the field to the factory. active constituent due to deterioration by storage or 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 11 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 micro- organism 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. 12 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 drug is dried in open air by: A. Exposure to sun: except if the active constituents or colour are affected. B. Shade drying by putting on the floor or trays in a single layer to retain 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 very high. Advantages & disadvantages of natural & artificial drying: Point of comparison Natural Drying ArtificiaDrying Advantage(s) Cheap -Rapid -It is done at controlled temperature -It stops enzymatic hydrolysis Disadvantage(s) It takes long time Methods of Artificial Drying: a) Chemical drying: The drug is placed in a desiccator with a dehydrating agent (quick lime, which 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). 13  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 changes. 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. 14 v. Pneumatic High Speed Drying (Flash Drying) The drug is dried by exposure to high temperature 800oC 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 become 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 certain cases a total change may occur. E.g., Tea leaves: dark, black (on slow drying), green (rapid drying): Reason: Presence of an oxidase enzyme (phlobatannins are changed into 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. 15 5. Constituents: Generally no change in constituents on drying. Sometimes change occur: E.g., Fresh Vanilla pods contain: a. Glucovanillin glycoside: on drying →It is hydrolysed → vanillin 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.. The general undesirable changes which may occur on storage are: Drugs containing volatile oils gradually lose their aroma. Ergot acquires disagreeable aroma. Digitalis leaves may lose their activity. 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. 16  Improper methods of storage: The principal factors responsible for deterioration of drugs are: 1. Physicochemical factors → moisture (humidity), heat, air and light. 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 may be 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 dark or by the use of 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 volatile oil such as clove and chamomile. d. Air Oxygen of air has an oxidation effect on the active constituents of some drugs leading to lowering the quality of products. Oxidative changes are sometimes required to produce the active constituents as in case of Frangula bark. 17 2. 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. ▪ The presence of fungi is indicated by their hyphae. B. Insects could be controlled by one of the following methods: i. Heat treatment: It is done by exposing the crude drugs to temperature 60-65oC 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. 18