PST05210 Basic Pharmacognosy

NTA Level 5 • Semester 2 • PST05210 Introduction to Pharmacognosy Basic Pharmacognosy • Source Session/Topic 1 Full source-text version: all educational wording from the extracted learning source is retained; only presenter/tutor metadata and web-layout noise are removed, while formatting is improved for readability. Session 1: Introduction to Pharmacognosy Total Session Time: 120 minutes Prerequisites • None Learning Tasks By the end of this session students are expected to be able to: • Define pharmacognosy • Explain the meaning of pharmacognosy • Define common terminologies applied in pharmacognosy • Identify uses of natural products • Historical background of pharmacognosy Resources Needed: • Flip charts, marker pens, and masking tape • Black/white board and chalk/whiteboard markers • LCD and laptop SESSION OVERVIEW |Step |Time |Activity/ |Content | | | |Method | | |1 |05 |Presentation |Introduction, Learning Tasks | | |minutes | | | |2 |15 |Presentation |Definition and Meaning of | | |minutes | |Pharmacognosy | |3 |20 |Presentation |Common Terminologies Applied | | |minutes | |in Pharmacognosy | |4 |20 |Brainstorming |Uses of Natural Products | | |minutes |Presentation | | |5 |40 |Presentation |Brief History of | | |minutes |Take home assignment |Pharmacognosy | |6 |05 |Presentation |Key Points | | |minutes | | | |7 |05 |Presentation |Evaluation | | |minutes | | | |8 |10minutes|Presentation |Assigment | SESSION CONTENTS STEP 1: Presentation of Session Title and Learning Tasks (5 minutes) READ or ASK students to read the learning tasks and clarify ASK students if they have any questions before continuing. STEP 2: Definition and Meaning of Pharmacognosy (15 minutes) • Pharmacognosy is a science which deals with the study of crude medicine (or unprepared form) in substances obtained originally from natural sources mainly plant, animal and minerals • The word Pharmacognosy is derived from the Greek words o "Pharmakon", meaning a drug or medicine and o "gignosco" meaning to acquire a knowledge of • It deals with scientific study of structural, physical, chemical and sensory characters of crude drug obtained from plant, animal and mineral sources. • Some materials have no pharmacological action but have interest to pharmacognosy e.g. natural fibres, flavouring and suspending agents, colorants, disintegrants, stabilizers, filtering and supporting media • Also other materials with natural associations with the subject are poisonous, hallucinogenic plants, allergens, herbicides, insecticides and molluscicides STEP 3: Common Terminologies Applied in Pharmacognosy (20 minutes) • Drug o Is a natural or synthetic substance used in the treatment, cure, prevention, or diagnosis of disease or used to otherwise enhance physical or mental wellbeing o Drugs should be included in the official pharmacopoeia • Crude drugs o Are harvested (i.e. dried) plant or animal sources which pharmaceutically or medicinally useful products, and before they undergo extensive processing or modification o A crude drug can be ▪ An entire organism (plant, animal, organism ▪ A part of an organism (a leaf or flower of a plant, an isolated gland or other organ of an anima ▪ An extract or an exudate of an organism o An isolated pure compound o Sources of Crude Drugs: ▪ Plant sources, e.g. Senna ▪ Animal sources, e.g. honey ▪ Minerals sources, e.g. talc • Natural Product o It is a chemical compound or substance produced by a living organism found in nature that usually has a pharmacological or biological activity for use in pharmaceutical drug discovery and drug design. • Ethnobotany o Is the study of the relationship between people and plants, field includes studying plants as medicines, alternative methods for healing, as wild foods, as agricultural crops; modes of transportation; as clothing and in the religious ceremonies. • Ethnopharmacology o Ethnopharmacology is the scientific study correlating ethnic groups, their health, and how it relates to their physical habits and methodology in creating and using medicines STEP 4: Uses of Natural Products (20 minutes) |Activity: Brainstorming (5 minutes) | | | |Ask students to brainstorm on the following question: | | | |What are the uses of natural products? | | | |ALLOW few students to respond | | | |WRITE their responses on the flip chart/ board | | | |CLARIFY and SUMMARISE by using the content below | • As medicines for the treatment of a wide range of diseases, e.g. morphine, atropine, digoxin, hormones, antibiotics • As pharmaceutical aids in pharmaceutical industry e.g. suspending & emulsifying agents, suppository bases, binders, sweetening and colouring agents • In cosmetics as flavouring and colouring agents • In culture media for the propagation of microorganisms in microbiology laboratories & biotechnology. • General uses e.g. in food industries: as dusting powders, as indicators and in perfumery. STEP 5: Brief History of Pharmacognosy (50 minutes) • The history of Pharmacognosy is synonymous with the history of medicine which originates in the health-related activities of the most primitive race of the remote past • Description of history of pharmacognosy is (therefore) embedded in the history of natural products in medicine • They acquired knowledge of medicinal properties of plants in the following ways o By guesswork or trial and error while searching food. o By superficial resemblance between plant parts and affected organs. o By accidental discovery. • The history of pharmacognosy can be divided into; o The Ancient Egyptian Period o The Babylonians o Old Indian medicine o The old Chinese medicine o The Greek and Romans o The Arabic Era o The 18th Century Pharmacognosists o The 19th Century Pharmacognosy o The 20th Century Pharmacognosy STEP 6: Key Points (5 minutes) • Pharmacognosy is a science which deals with the study of crude medicine (or unprepared form) in substances obtained originally from natural sources mainly plant, animal and minerals • Sources of crude drugs include plants, animals and minerals • Knowledge of medicinal properties of plants is acquired by guesswork or trial and error while searching for food, by superficial resemblance between plant parts and affected organs and by accidental discovery STEP 7: Evaluation (5 minutes) • What is crude drug mean? • What are the uses of

NTA Level 5 • Semester 2 • PST05210 Cultivation of medicinal plants Basic Pharmacognosy • Source Session/Topic 12 Full source-text version: all educational wording from the extracted learning source is retained; only presenter/tutor metadata and web-layout noise are removed, while formatting is improved for readability. Session 12: Cultivation of medicinal plants Total Session Time: 120 minutes Prerequisites • None Learning Tasks By the end of this session students are expected to be able to: • Classify medicinal plants • Explain the cultivation of medicinal plants • List factors affecting cultivation of medicinal plants • Explain the importance of plant as a major source of drugs • List available plants commonly used as source of drugs in Tanzania Resources Needed: • Flip charts, marker pens, and masking tape • Black/white board and chalk/whiteboard markers • LCD projector and laptop SESSION OVERVIEW |Step |Time |Activity/ |Content | | | |Method | | |1 |05 minutes |Presentation |Introduction, Learning Tasks | |2 |20 minutes |Presentation |Classification of Medicinal Plants| | | |Buzzing | | |3 |30 minutes |Presentation |Cultivation of Medicinal Plants | | | |Brainstorming | | |4 | | |Factors Affecting Cultivation of | | |25 minutes |Presentation |Medicinal Plants | |5 |20 minutes |Presentation |Plant Breeding Methods | |6 |05 minutes |Presentation |Key Points | |7 |05 minutes |Presentation |Evaluation | |8 |10minutes |Presentation |Assignment | SESSION CONTENTS STEP 1: Presentation of Session Title and Learning Tasks (5 minutes) READ or ASK students to read the learning objectives and clarify ASK students if they have any questions before continuing. STEP 2: Classification and Nomenclature of Medicinal Plants (20 minutes) • Classification of medicinal plants o Alphabetical Classification ▪ This classification employs the use of either Latin or Vernacular names of the medicinal plant ▪ This method is simple and suitable for quick reference ▪ Disadvantageously, this method does not give indication of interrelationships between drugs e.g. in Pharmacopoeias o Taxonomic Classification ▪ This method is based on botanical classification ▪ Drugs are arranged according to the plants from which they are obtained ▪ Drugs are grouped into families, Classes, orders, genera and species o Morphological Classification ▪ Physical features of the drugs are used in the classification • Organized drugs o For instance, leaves, flowers, fruits, seeds, wood, barks, rhizomes & roots • Unorganized drugs o For instance, dried lattices, extracts, gums, resins, oils, fats and waxes o Pharmacological or therapeutic Classification ▪ Drugs are classified according to pharmacological actions of their most important constituents or their therapeutic uses, e.g. cardiotonic drugs, CNS stimulants, Muscle relaxants, etc. o Chemical or Biogenetic Classification ▪ Drugs are classified according to their important constituents e.g. alkaloids, glycosides, volatile oils ▪ They are also classified based on their biosynthetic pathways • Nomenclature in Medicinal Plants o The binomial system founded by the Swedish biologist Linnaeus is used o The first name (genus name) starts with a capital letter and the second name (species) begins with a small letter o Genus and species names may be followed by author’s name who first described the species or variety. e.g. Artemisia cina Berg., Caryophyllos aromaticus L o Sometimes, species name is derived from author’s name, e.g. Cinchona Ledgeriana after Charles Ledger o The species name usually indicates certain characteristics of the plant e.g. ▪ Cassia acutifolia means “sharp pointed leaflets” ▪ Atropa belladonna (bella= beautiful, donna=lady) ▪ Piper nigrum (black) ▪ Myristica fragrans (nice aroma) ▪ Hydrastis Canadensis (growing in Canada) ▪ Papaver sominferum (inducing sleep) o The generic name may indicate certain characters of the plant e.g. ▪ Glycyrrhiza means gluco = sweet, riza = root, STEP 3: Cultivation of Medicinal Plants (30 minutes) • Drugs may be collected from wild or cultivated plants • Collection may be done by skilled or unskilled labour • Collection from cultivated sources ensure sustainability of medicinal plants • In some cases, pharmacopoeias specify cultivated species such as Fennel, ginger, cinnamon and opium • Disadvantages of Wild Plant Collection o Sparse distribution e.g. Sceletium tortuosum. Potentially difficult to transport plant to area of processing o Difficult access (e.g. forests, mountains etch) o Collector ignorance leads to admixture of other plants, collection of undesired plant parts or stage of development or during an incorrect season ( loss of medicinal activity. o Damage to natural environment which leads to extinction of a species. |Activity: Brainstorming (5 minutes) | | | |Ask students to brainstorm on the following question: | | | |What are the advantages of cultivation of medicinal plants? | | | |ALLOW few students to respond? | | | |WRITE their responses on the flip chart/ board | | | |CLARIFY and SUMMARISE by using the content below | • Advantages of Cultivated Medicinal Plants o Only desired species are collected therefore uniform quality. o Collection, transport and access to processing facilities is improved. o Better control of soil quality, pests and plant disease. o Supply: Constant and Regular (Controlled) o Collectors are trained STEP 4: Factors Affecting Cultivation of Medicinal Plants (25 minutes) • Environmental (Exogenous) Factors o Temperature ▪ It is a major factor that affects both the growth/development and metabolism of the plants ▪ Each plant is specialized to adapt to its native environment ▪ But most plants are able to exist in wide temperature ranges e.g. Tropical and Sub-tropical plants in temperate regions ▪ Temperature affects plant chemical reaction rates • e.g. Datura stramonium produces lower alkaloids in cloudy/rainy weather (winter) • Volatile oils are produced more readily in warmer weather o Very hot days lead to a physical loss of oil • Growing peppermint in shade rather than the sun. o Rainfall ▪ Annual rainfall, distribution, humidity effect medicinal plants ▪ Rainfall influences the production of glandular hairs ▪ Continuous rainfall may lead to loss of water-soluble substances such as glycosides, tannins, flavonoids and some volatile oils through leaves and roots o Day-length (sunlight) ▪ Amount and intensity of light needed differs from plant to plant ▪ Amount of glycosides, alkaloids and volatile oils

NTA Level 5 • Semester 2 • PST05210 Collection, Processing and Storage of Medicinal Plants Basic Pharmacognosy • Source Session/Topic 13 Full source-text version: all educational wording from the extracted learning source is retained; only presenter/tutor metadata and web-layout noise are removed, while formatting is improved for readability. Session 13: Collection, Processing and Storage of Medicinal Plants Total Session Time: 120 minutes Prerequisites • None Learning Tasks By the end of this session students are expected to be able to: • List methods for collection of medicinal drugs • Explain the importance of processing medicinal plants • Explain methods of drying of crude drugs • Explain storage of medicinal plants Resources Needed: • Flip charts, marker pens, and masking tape • Black/white board and chalk/whiteboard markers • Computer and LCD Projector SESSION OVERVIEW |Step |Time |Activity/ |Content | | | |Method | | |1 |05 minutes |Presentation |Introduction, Learning Tasks | |2 |30 minutes |Presentation |Collection of Medicinal Plants | |3 |45 minutes |Presentation |Processing of Crude Drugs | |4 | |Small group |Storage of Crude Drugs | | |30 minutes |Discussion | | | | |Presentation | | |5 |05 minutes |Presentation |Key Points | |6 |05 minutes |Presentation |Evaluation | SESSION CONTENTS STEP 1: Presentation of Session Title and Learning Tasks (5 minutes) READ or ASK students to read the learning objectives and clarify ASK students if they have any questions before continuing. STEP 2: Collection of Medicinal Plants (30 minutes) • Collection refers to harvesting or obtaining drugs from medicinal plants • Drugs may be collected from wild or cultivated plants • Collection may be done by skilled or unskilled labour • Collection from cultivated plants is more advantageous and ensures sustainability of medicinal plants • In some cases, pharmacopoeias specify collection of certain drugs from cultivated species such as Fennel, ginger, cinnamon and opium • Some drugs e.g. senna, tragacanth and others may be collected from wild or cultivated species. • Active constituents in plants vary in amount and nature throughout the year, so collection should be done at the right time when active constituents are at the highest levels. For instance, o Time (season) of the year ▪ Rhubarb contains high levels of anthranols in winter and high levels of anthraquinones in summer. Anthranol are oxidized to anthraquinones in summer o Time of the day ▪ Digitalis is collected in the afternoon contains more cardiac glycosides ▪ Solanaceous leaves collected in the morning have more alkaloids o Stage of maturity ▪ In Eugenia caryophyllus, buds contain high oil but mother “blown” cloves contain very little oil ▪ Vanilla has highest levels of vanillin 8 months after flowers open • General factors to consider when harvesting/collecting drugs from medicinal plants; o Underground organs are collected when aerial parts die down o Leaves are collected when flowers are beginning to open o Flowers are collected in dry weather and just before they fully expand e.g. cloves o Fruits and seeds are collected when fully mature but unripe o Barks are collected in damp weather o Unorganized drugs are collected in dry weather o Leaves, flowers and fruits should not be collected when covered with dew or rain o Discoloured or parts attacked by insects should not be collected o Large organs should be sliced soon after collection to facilitate drying o Limits of unwanted parts in desired parts must be considered when collecting medicinal plants e.g. aerial stems in rhizomes STEP 3: Processing of Crude Drugs (45 minutes) • After collection, drugs should be processed to meet various requirements such as market requirements • Processing of crude drugs is important in order prevent deterioration • Processing of drugs from natural sources depends on morphological nature, constituents, geographical source and other related factors • Drying is an important aspect of processing crude drugs o There various reasons for drying drugs obtained from medicinal plants ▪ To decrease size and weight i.e. to facilitate packing, transport and storage ▪ To facilitate powdering ▪ To prevent enzyme action ▪ To prevent microbial growth ▪ To prevent degradation of active constituents o Enzyme action may be desired or undesirable after collection ▪ When enzyme action is desired after collection e.g. in vanilla pods, gentian roots and cocoa seeds, the collected drug is dried slowly at moderate temperature ▪ Drying is done as soon as possible after harvesting when enzyme reaction is not desired e.g. digitalis leaves o Methods of Drying o There are various methods that are used in drying crude drugs o The choice of a drying method depends on physical characteristics of the plant and chemical characteristics of the active constituents ▪ Air Drying • Sun Drying o Is done when drugs are not adversely affected by excessive sunlight. o Drugs are dried in thin layers and tuned over occasionally o Drugs dried in this way include clove and cardamom • Shade Drying o Done when sunlight causes discoloration and warping/shrivelling of the drugs e.g. cinnamon ▪ Artificial Drying • Artificial source of heat is used in the drying process • Drying in the oven (oven drying) is the commonest methods used in artificial drying • Artificial drying is more accepted and more rapid than air-drying • Artificial drying is more suitable for use in the wet weather • Drying temperature is governed by constituents o Generally, leaves, herbs and flowers are dried between 20-40oC, barks and roots: 40-65oC • When done rapidly, the drugs retain colour and aroma ▪ Vacuum Drying • It is also done in oven, but at low temperature • Low pressure ensures rapid and complete drying • It is an expensive method and thus reserved for expensive drugs or drugs which cannot be sufficiently dried by other methods ▪ Lyophilisation • Involves freezing of the drug and then evaporation under low pressure • Very suitable method for drugs that are very sensitive to heat • The resulting product is a fine powder • This method is used for drying biological fluids, enzymes, proteins

NTA Level 5 • Semester 2 • PST05210 Extraction of Active Medicinal Principles from Natural Sources Basic Pharmacognosy • Source Session/Topic 14 Full source-text version: all educational wording from the extracted learning source is retained; only presenter/tutor metadata and web-layout noise are removed, while formatting is improved for readability. Session 14: Extraction of Active Medicinal Principles from Natural Sources Total Session Time: 120 minutes Prerequisites • None Learning Tasks By the end of this session students are expected to be able to: • Definition of terms • List types of extracts • Explain factors affecting extraction process • Explain Mechanism of solvent extraction • Outline properties and types solvents • Explain methods for extraction of active drugs Resources Needed: • Flip charts, marker pens, and masking tape • Black/white board and chalk/whiteboard markers • LCD Projector and laptop SESSION OVERVIEW |Step |Time |Activity/ |Content | | | |Method | | |1 |05 minutes |Presentation |Introduction, Learning | | | | |Tasks | |2 |10 minutes |presentation |Definition of terms | |3 |05 minutes |Presentation |Types of extracts | |4 |30 minutes |Presentation |Properties and types of | | | |buzzing |solvents | |5 |15 minutes |Presentation |Mechanism of Solvent | | | | |Extraction | |6 |05 minutes |Presentation |Factors affecting | | | | |extraction | |7 |40 minutes |Presentation |Methods of extraction | | | |Small group Discussion| | |8 |05 minutes |Presentation |Key Points | |9 |05 minutes |Presentation |Evaluation | SESSION CONTENTS STEP 1: Presentation of Session Title and Learning Objectives (05 minutes) READ or ASK students to read the learning objectives and clarify ASK students if they have any questions before continuing. STEP 2: Definition of terms (10 Minutes) • Extraction is the method of removing active constituents from a solid or liquid by means of liquid solvent. o The separation of medicinally active portions of plant or animal tissues from the inactive or inert components by using selective solvents. o In this method the wanted components are dissolved by the use of selective solvents known as menstrum & undissolved part is a marc, after the extraction unwanted matter is removed. • Extract: Extracts can be defined as preparations of crude drugs which contain all the constituents which are soluble in the solvent. • Marc: Solid residue obtain after extraction Menstruum • Solvent is a liquid substance capable to dissolve other substances (solutes) without chemical changes. o (The term “Solvents” refers to a class of chemical compounds described by function – the term derives from Latin, meaning roughly to “loosen.” In chemistry, solvents – which are generally in liquid form – are used to dissolve, suspend or extract other materials, usually without chemically changing either the solvents or the other materials Step 3: Types of Extracts (05 minutes) • Type of extracts o Dry extract (Tab, cap.) E.g. belladonna extract o Soft (Ointment, suppository) E.g. glycerrhiza extract. o Liquid: As tincture. STEP 4: Properties and Types of Solvents (30 minutes) |Activity: Buzzing (10 minutes) | | | |DIVIDE students into small manageable groups | | | |ASK students to discuss on the following question | | | |What are types of solvents? | | | |ALLOW students to discuss for 15 minutes | | | |ALLOW few groups to present and the rest to add points not | |mentioned | | | |CLARIFY and SUMMARIZE by using the contents below | • Types of Solvent o Molecular structure of solvents o Inorganic solvents o Organic solvents • Molecular structure of solvents o Molecular structure of solvents, Ability of a substance to dissolve another substance is determined by compatibility of their molecular structures (like dissolves like). ▪ Types of molecular structures of the solvents are as follows: • Polar protic solvents o A polar protic molecule consists of a polar group OH and a non- polar tail. The structure may be represented by a formula R-OH. Polar protic solvents dissolve other substances with polar protic molecular structure. Polar protic solvents are miscible with water (hydrophilic). Examples of polar protic solvents: ▪ Water (H-OH), ▪ Acetic acid (CH3CO-OH) ▪ Methanol (CH3-OH), ▪ Ethanol (CH3CH2-OH), ▪ n-propanol (CH3CH2CH2-OH), ▪ n-butanol (CH3CH2CH2CH2-OH). • Dipolar aprotic solvent o Dipolar aprotic molecules possess a large bond dipole moment (a measure of polarity of a molecule chemical bond). They do not contain OH group. Examples of dipolar aprotic solvents:\ ▪ Acetone ((CH3)2C=O), ▪ Ehyl acetate (CH3CO2CH2CH3), ▪ Dimethyl sulfoxide ( (CH3)2SO ), ▪ Acetonitrile (CH3CN), ▪ Dimethylformamide ( (CH3)2NC(O)H ). • Non-polar solvents o Electric charge in the molecules of non-polar solvents is evenly distributed, therefore the molecules have low dielectric constant. Non-polar solvents are hydrophobic (immiscible with water). Non-polar solvents are liphophilic as they dissolve non- polar substances such as oils, fats, greases. Examples of non-polar solvents: ▪ carbon tetrachloride (CCl4), ▪ benzene (C6H6), ▪ and diethyl ether ( CH3CH2OCH2CH3), ▪ hexane (CH3(CH2)4CH3), ▪ methylene chloride (CH2Cl2). • Inorganic solvents o The most popular inorganic (not containing carbon) solvents are o water (H2O) and aqueous solutions containing special additives (surfacants, detergents, PH buffers, inhibitors). o Other inorganic solvents are liquid anhydrous ▪ Ammonia (NH3), ▪ concentrated sulfuric acid (H2SO4), ▪ sulfuryl chloride fluoride (SO2ClF). • Organic solvents o Oxygenated solvent is an organic solvent, molecules of which contain oxygen. Oxygenated solvents are widely used in the paints, inks, pharmaceuticals, fragrance sectors, adhesives, cosmetics, detergents, food industries. Examples of oxygenated solvents: ▪ Alcohols, ▪ Glycol ethers, ▪ Methyl acetate, ▪ Ethyl acetate, ▪ Ketones, ▪ Esters, ▪ Glycol ether/esters STEP 5: Mechanism of Solvent Extraction (15 minutes) • Mechanism of solvent extraction o Dissolution of extractive substances out of disintegrated cells. o Dissolution of extractive substances out of intact plant cell by diffusion (requires steeping and swelling) o Penetration of the solvent into the plant cells and swelling of the cells. o Diffusion of the dissolved extractive substances out of the cell. o Plant constituents are usually contained inside the cells. o Therefore, the solvent used for extraction must diffuse into

NTA Level 5 • Semester 2 • PST05210 Adulteration of Medicinal Plants Basic Pharmacognosy • Source Session/Topic 15 Full source-text version: all educational wording from the extracted learning source is retained; only presenter/tutor metadata and web-layout noise are removed, while formatting is improved for readability. Session 15: Adulteration of Medicinal Plants Total Session Time: 60 minutes Prerequisites • None Learning Tasks By the end of this session students are expected to be able to: • Define adulteration • List methods of adulteration • Explain the effects of adulteration Resources Needed: • Flip charts, marker pens, and masking tape • Black/white board and chalk/whiteboard markers • LCD projector and Laptop SESSION OVERVIEW |Step |Time |Activity/ |Content | | | |Method | | |1 |05 minutes |Presentation |Introduction, Learning Tasks | |2 |10 minutes |Presentation |Meaning of Adulteration | |3 | 25 |Presentation |Methods and Effects of | | |minutes | |Adulteration | |4 |05 minutes |Presentation |Key Points | |5 |05 minutes |Presentation |Evaluation | |6 | 10minutes |Presentation |Assignment | SESSION CONTENTS STEP 1: Presentation of Session Title and Learning Tasks (5 minutes) READ or ASK students to read the learning objectives and clarify ASK students if they have any questions before continuing. STEP 2: Meaning of Adulteration (10 minutes) • Adulteration is defined as anything causing debasement of a drug • An adulterant is a medicinal plant which does not conform to official standards or which does not comply with the requirement of the pharmacopoeia cheap and easily available in large quantities o An adulterant must be • Adulteration or debasement of medicinal plants are of two major types; o Deliberate adulteration ▪ This is intentional and normally commercial mainly for enhancement of profits o Accidental adulteration • Deliberate adulteration is usually practised when certain medicinal plants are scarce or expensive • Adulteration of crude drugs usually involves practices such as substitution of the original crude drugs partially or fully with other substances which are either free from or inferior in therapeutic and chemical properties • Adulteration can occur through; o Faulty collection of the drug o Improper preparation of the drug o Poor storage condition o Deliberate practices • Reasons for adulteration of crude drugs include; o Scarcity of the drug o High price of the drug in the market e.g. clove, cardamom o Contraband drug e.g. opium STEP 3: Methods and Effects of Adulteration (25 minutes) • Inferior medicinal plant quality o Which leads to a sub-standard drug o This may result from; ▪ Ignorance/carelessness e.g. collection of genuine material regardless of the time factor –collecting herbs prior/after ideal time ▪ Collection at incorrect stage of development e.g. coriander – fully ripe fruits (should be nearly ripe), clove (flowers in bud stage) ▪ Collection of parts which are not medicinally valuable e.g. Chamomile leaves ▪ Collection of incorrect herb (close resemblance to intended herb) ▪ Imperfect preparation e.g. not removing undesired parts e.g. cork from ginger rhizome/incorrect drying conditions ▪ Incorrect storage: e.g. volatile oils: cool, dry place in air tight containers ▪ Inferiority may be avoided by careful selection of the plant material • Spoilage of Drug o When the quality or medicinal value/ usefulness of herb is impaired or destroyed by bacterial/ fungal action, insects, rodents or other pests o Normally results from incorrect storage (effects of water/temperature) o Avoided by careful attention to the drying and storage conditions • Deterioration o Occurs when value or quality of the drug has been impaired • Admixture o Admixture occurs when another species is added to the medicinally valuable drug; intentional or accidentally o This may result from; ▪ Poor collection due to unskilled labour ▪ Presence of plant parts other than those allowed by the definition ▪ Collection of foreign material (stones, dirt) • Sophistication with inferior varieties o This is the deliberate addition of inferior material with the intention of decreasing medicinal action of the desired drug e.g. ▪ Candle wax coloured yellow and being offered as Beeswax ▪ Addition of flour to powdered ginger with chillies for potency • Substitution o Substitution is the addition of an allied drug, or one which is botanically different e.g. Digitalis thaspi for Digitalis purpurea • Addition of worthless heavy materials o Large mass of stomes mixed with liquorice root, pieces of limestone are added in asafoedita • Adulteration causes problems in natural drugs STEP 4: Key Points (5 minutes) • Adulteration addition of anything into the crude drugs that causes debasement of that drug • An adulterant is a medicinal plant which does not conform to official standards or which does not comply with the requirement of the pharmacopoeia. • Deliberate adulteration is usually practiced when the drug in question is scarce or expensive STEP 5: Evaluation (5 minutes) • What is adulteration of crude drugs? • What is sophistication? • What are effects of adulteration? STEP 6: Take Home Assignment (10 minutes) |Activity: Take Home Assignment (10 minutes) | | | |DIVIDE students in groups or individuals | | | |ASK the students to work on the following Assignment | |List monographs of medicinal plants | |List the effects of adulteration | |List classes of plants containing toxic substances | |List toxic substances from plants | |List common misuses of medicinal plants | | | |ALLOCATE time for students to do the assignments and submit | | | |REFER students to recommended reference | References Trease, G. E., Evans, W. C., & Evans, D. (2009). Trease and Evans pharmacognosy. London: Saunders. Joanne Barnes et al (2002), Herbal medicines 3rd Edition: Pharmaceutical Press Wallis, T. E. (2005). Textbook of pharmacognosy. New Delhi: CBS. Robbers, J. E., Speedie, M. K., Tyler, V. E., & Tyler, V. E. (1996). Pharmacognosy and pharmacobiotechnology. Baltimore: Williams & Wilkins. Heinrich, M., Kinghorn, A. D., Maizels, D., Gibbons, S., & Phillipson, J. D. (2012). Fundamentals of pharmacognosy and phytotherapy. Edinburgh: Churchill Livingstone/Elsevier. ← Previous TopicNext Topic →View all Basic Pharmacognosy topicsOpen Complete Full Notes PDF / OFFLINE NOTES Unataka kutumiwa notes hizi

NTA Level 5 • Semester 2 • PST05210 Introduction to Ergastic Substances Basic Pharmacognosy • Source Session/Topic 16 Full source-text version: all educational wording from the extracted learning source is retained; only presenter/tutor metadata and web-layout noise are removed, while formatting is improved for readability. Session 16: Introduction to Ergastic Substances Total Session Time: 120 minutes Prerequisites • None Learning Tasks By the end of this session students are expected to be able to: • Define ergastic substances • Classify ergastic substances • Describe carbohydrates • Describe proteins • Gums, mucillages and Pectins • Describe tannins • Describe ergastic crystals Resources Needed: • Flip charts, marker pens, and masking tape • Black/white board and chalk/whiteboard markers • LCD projector and laptop SESSION OVERVIEW |Step |Time |Activity/ |Content | | | |Method | | |1 |05 minutes |Presentation |Introduction, Learning | | | | |Tasks | |2 |10 minutes |Presentation |Meaning and Classification| | | | |of Ergastic Substances | |3 | |Presentation |Carbohydrates | | |15 minutes |Buzzing | | |4 | |Small group discussion|Proteins | | |25 minutes |Presentation | | |5 |15 minutes |Presentation |Gums, Mucillages and | | | | |Pectins | |6 |15 minutes |Presentation |Tannins | |7 |25 minutes |Presentation |Ergastic Crystals | |8 |05 minutes |Presentation |Key Points | |9 |05 minutes |Presentation |Evaluation | SESSION CONTENTS STEP 1: Presentation of Session Title and Learning Objectives (5 minutes) READ or ASK students to read the learning objectives and clarify ASK students if they have any questions before continuing. STEP 2: Meaning and Classification of Ergastic Substances (10 minutes) • Ergastic substances are non-living cell contents which can be identified by microscopical examination or by chemical and physical tests • Ergastic substances are food reserve (storage products) or by-products of metabolism (excretory/secretory products) • Classes of ergastic substances are; o Carbohydrates o Proteins o Fixed oils and fats (Elaioplasts/spherosomes) o Alkaloids (and purines) o Glycosides o Gums, mucilages and Pectins o Volatile oils and Resins o Tannins o Crystals (Calcium oxalate, calcium carbonate and silica) STEP 3: Carbohydrates (15 minutes) |Activity: Buzzing (10 minutes) | | | |DIVIDE students into small manageable groups | | | |ASK students to discuss on the following question | | | |What are the characteristics and chemicals tests of cellulose and | |starch? | | | |ALLOW students to discuss for 10 minutes | | | |ALLOW few groups to present and the rest to add points not mentioned| | | | | |CLARIFY and SUMMARIZE by using the contents below | • Cellulose and starch are the main ergastic substances of plant cells • Cellulose is the chief component of cell wall • Starch occurs as a reserve material in the protoplasm o Found in plastids (leucoplasts and amyloplasts) o Occurs in granules (starch grains) of different sizes in almost all organs of plants o Occurs abundantly in roots, rhizomes, fruits and seeds o Physical tests: ▪ Pure starch is a white, tasteless and odourless powder insoluble in cold water or alcohol o Chemical tests for starch granules ▪ Starch are unique in shape of starch granules in granular size, shape and crystallization pattern ▪ Starch grains are observed under the microscope e.g. when stained with iodine STEP 4: Proteins (25 minutes) |Activity: Small Group Discussion (10 minutes) | | | |DIVIDE students into small manageable groups | |ASK students to discuss on the following question | | | |What are the characteristics and chemicals tests of proteins? | | | |ALLOW students to discuss for 10 minutes | |ALLOW few groups to present and the rest to add points not | |mentioned | | | |CLARIFY and SUMMARIZE by using the contents below | • Proteins are large macromolecules made up of long chains of amino acids joined by peptide bond • Proteins are the main component of living protoplasm • Proteins also occur as inactive ergastic bodies in amorphous or crystalline forms • They occur in form of aleurone grains which are well seen in oily seeds (e.g. castor seeds) • Simplest aleurone grain consists of a mass of proteins surrounded by a thin membrane • Ground mass of protein encloses one or more rounded bodies or globoids and an angular body known as crystalloids • So, microscopically, they are observed as mass of protein surrounded by thin membrane (globoidal in shape) • Aleurone grain are best seen after deflating and removal of starch (if starch is present in large amounts) • Chemical tests o Millon’s reagent, which stains the protein red on warming o Iodine solution, which stain the ground substance and crystalloid yellowish-brown but leaves the globoids unstained o Picric acid which stain stains the ground substance and crystalloid yellow STEP 5: Gums, Mucillages and Pectins (15 minutes) • These are polysaccharides complexes formed from sugar and uronic acid units • They are insoluble in alcohol but dissolve or swell in water • They are usually formed from the cell wall e.g. tragacanth or they are deposited on the cell wall in successive layers • When cells containing these substances are mounted in alcohol and irrigated with water, stratifications (of the successive layers of these ergastic substances) may often be seen e.g. Mustard and linseed • Tests o There are no specific tests for these substances o The official solution of Ruthenium red • Stains the mucilage of Senna and Buchu leaves, Althea, Linseed and Mustard o Alkaline solution of Corallin • Stains some forms of mucilage e.g. mucilage from Squill o Chlor-zinc-iodine or Methylene blue dissolved in alcohol and glycerine ▪ Stain some mucilage STEP 6: Tannins (15 minutes) • Tannins are phenolic compounds obtained from various parts of different plants • Tannins are widely distributed in plants • Occur in solution in cell sap, often in distinct vacuole • Are abundant in the tree bark, wood, fruit, fruit pod, leaves, and roots • Tannins are obtained from plants like wattle (Acacia sp.), oak (Quercus sp.), eucalyptus (Eucalyptus sp.), willow (Salix caprea),

NTA Level 5 • Semester 2 • PST05210 Gum, Mucilage and Pectins Basic Pharmacognosy • Source Session/Topic 17 Full source-text version: all educational wording from the extracted learning source is retained; only presenter/tutor metadata and web-layout noise are removed, while formatting is improved for readability. Session 17: Gum, Mucilage and Pectins Total Session Time: 120 minutes Prerequisites • None Learning Tasks By the end of this session students are expected to be able to: • Define gum, mucilage and pectins • Explain natural source, constituents and uses of Tragacanth gum • Explain natural source, constituents and uses of Acacia gum • Explain natural source, constituents and uses of Sterculia gum • Explain natural source, constituents and uses of Psyllium Resources Needed: • Flip charts, marker pens, and masking tape • Black/white board and chalk/whiteboard markers SESSION OVERVIEW |Step |Time |Activity/ |Content | | | |Method | | |1 |05 minutes |Presentation |Introduction, Learning Tasks | |2 |15 minutes |Presentation |Introduction to Gum, Mucilage and | | | | |Pectins | |3 |25 minutes |Presentation |Natural Source, Constituents and | | | | |Uses of Tragacanth Gum | |4 |25 minutes |Presentation |Natural Source, Constituents and | | | |Buzzing |Uses of Acacia Gum | |5 |20 minutes |Presentation |Natural Source, Constituents and | | | | |Uses of Sterculia Gum | |6 |20 minutes |Presentation |Natural Source, Constituents and | | | |Brainstorming |Uses of Psyllium | |7 |05 minutes |Presentation |Key Points | |8 |05 minutes |Presentation |Evaluation | SESSION CONTENTS STEP 1: Presentation of Session Title and Learning Tasks (5 minutes) READ or ASK students to read the learning objectives and clarify ASK students if they have any questions before continuing. STEP 2: Introduction to Gums, Mucilage and Pectins (15 minutes) • Gums and mucilage have similar constitutuons and on hydrolysis yield a mixture of sugar and uronic acids. • Gums are considered to be pathological products formed upon injury of the plant or owing to unfavourable conditions such as draught, by a breakdown of cell walls e.g. tragacanth (extracellular formation gummosis) • They are insoluble in alcohol but dissolve or swell in water • Conversely, mucilage are generally normal products of metabolism formed within the cell (intracellular formation) and may represent storage material, a water storage reservoir or a protection for germinating seeds. • They are often found in quantity in the epidermal cells of leaves, e.g senna, in seed coats (linseed, psyllium etc.) roots (marshmallow) and barks (slippery elm) STEP 3: Natural Source, Constituents and Uses of Tragacanth Gum (25 minutes) • Definition o Tragacanth is the “air hardened gummy exudate flowing naturally or obtained by incision, from the trunk & branches of Astragalus gummifer (Labillardiere) and certain other spp. of Astragalus o Tragacanth is the gum that exudes immediately after injury of the plant occurs and is therefore pre-formed in the plant • Constituents o Tragacanthin o Bassorin o Sugar o Uronic acids • Uses o Used as a suspending agent for insoluble powders o Binding agent in pills and tablets o Emulgent o A binding agent in food industry STEP 4: Natural Source, Constituents and Uses of Acacia Gum (25 minutes) • Definition o Acacia gum is a dried gum obtained from the stem and branches of Acacia senegal and some other spp of Acacia (Leguminoseae). • Constituents o Arabin (Arabic acid) o Galactose o Arabinose o Rhamnose o Uronic acids o Oxidase enzyme |Activity: Buzzing (5 minutes) | | | |ASK students to pair up and buzz on the following question for 2 | |minutes | | | |What are the uses of acacia gum in pharmacy? | | | |ALLOW few pairs to respond and let other pairs to add on points not | |mentioned | | | |WRITE their response on the flip chart/board | | | |CLARIFY and SUMMARIZE by using the content below | • Uses o Used as a general stabilizer in emulsions o Used in lozenges o As demulcent o Used for treatment of diarrhoea, cough and sore throat o It is also widely used in food and drink industries STEP 5: Natural Source, Constituents and Uses of Sterculia Gum (20 minutes) • Definition o Sterculia gum is the gummy exudate obtained from the tree, Sterculia urens (Sterculiaceae). • Constituents o Uronic acids o Partial hydrolysis yields ▪ D-galactose ▪ L-rhamnose ▪ D-galacturonic acid ▪ Acetic acid • Uses o Granular grades are used as a bulk laxative (second only to psyllium seed in use as a bulk laxative). o Powdered gum is used in lozenges, pastes and denture fixture powders. STEP 6: Natural Source, Constituents and Uses of Psyllium (20 minutes) • Definition o Psyllium consists of the dried, ripe seeds of Plantago afra (Plantago psyllium), P. indica (P. arenaria) and P. ovata (Plantaginaceae) • Constituents o Mucilage o Fixed oil o Sugars o Sterols o Protein |Activity: Buzzing (5 minutes) | | | |ASK students to pair up and buzz on the following question for 2 | |minutes | | | |What are the uses of psyllium? | | | |ALLOW few pairs to respond and let other pairs to add on points not | |mentioned | | | |WRITE their response on the flip chart/board | | | |CLARIFY and SUMMARIZE by using the content below | • Uses of Psyllium o Psyllium is mainly used as a ▪ Dietary fibre to relieve symptoms of both constipation ▪ Mild diarrhea ▪ Occasionally as a food thickener. ▪ Research has shown lowering of blood cholesterol levels in people with elevated cholesterol, ▪ Lowering of blood glucose levels in people with type 2 diabetes. STEP 7: Key Points (5 minutes) • Gums, mucilage and pectins have similar constitutuons and on hydrolysis yield a mixture of sugar and uronic acids. • Gums are pathological products formed upon injury of the plant or owing to unfavourable conditions such as draught, by a breakdown of cell walls e.g. tragacanth • Acacia gum is a dried gum obtained from

NTA Level 5 • Semester 2 • PST05210 Introduction to Alkaloids Basic Pharmacognosy • Source Session/Topic 18 Full source-text version: all educational wording from the extracted learning source is retained; only presenter/tutor metadata and web-layout noise are removed, while formatting is improved for readability. Session 18: Introduction to Alkaloids Total Session Time: 120 minutes Prerequisites • None Learning Tasks By the end of this session students are expected to be able to: • Explain the occurrence and distribution of alkaloids • Explain naming of alkaloids • Explain properties of alkaloids Resources Needed: • Flip charts, marker pens, and masking tape • Black/white board and chalk/whiteboard markers SESSION OVERVIEW |Step |Time |Activity/ |Content | | | |Method | | |1 |05 minutes |Presentation |Introduction, Learning Tasks | |2 |35 minutes |Presentation |Occurrence and Distribution of | | | | |Alkaloid | |3 |35 minutes |Presentation |Naming of Alkaloids | |4 |35 minutes |Presentation |Properties of Alkaloids | |5 |05 minutes |Presentation |Key Points | |6 |05 minutes |Presentation |Evaluation | SESSION CONTENTS STEP 1: Presentation of Session Title and Learning Tasks (5 minutes) READ or ASK students to read the learning objectives and clarify ASK students if they have any questions before continuing. STEP 2: Occurrence and Distribution of Alkaloids (35 minutes) • Alkaloids are basic naturally occurring compounds containing one or more nitrogen atoms usually in a heterocyclic ring and have a marked physiological action on man or other animals • Some alkaloids occur in certain families while others only occur in specific species • Alkaloids are highly found in apocynaceae, rubiaceae, solanaceae and papaveracea • Alkaloids are not found in rosaceae and labiatae families • Alkaloids are produced by a large variety of organisms, including bacteria, fungi, plants, and animals • Most alkaloids are basic (form salts with acids) • Some alkaloids are not basic e.g. colchicine, piperine, quaternary alkaloids. • The nitrogen in some alkaloids is not in a heterocyclic ring e.g. Ephedrine, Colchicine, Mescaline. • Alkaloids are rare in lower plants and richer in dicots than in monocots • Alkaloids may occur in free state (e.g. as free bases), as salts (e.g. with organic acids), as glycosides, and as alkaloid N-oxides • Alkaloids may be found in all parts of the plant, in barks, seeds, roots, fruits, leaves and in latex • Functions of alkaloids in the plant; o Protect against insects and herbivores due to their bitterness and toxicity o Are final products of detoxification in some cases. o Source of nitrogen in case of nitrogen deficiency o Act as growth regulators in certain metabolic systems. STEP 3: Properties of Alkaloids (35 minutes) • Physical properties o Most alkaloids are crystalline solids, a few are amorphous solids e.g. emetine. o Some are liquids that are either volatile or non-volatile o Majority of the alkaloids are colorless but some are colored; o Alkaloidal bases are soluble in organic solvents and insoluble in water o Salts of alkaloids are usually soluble in water and, insoluble or sparingly soluble in organic solvents. o Alkaloids are bitter tasting o Many alkaloids are extremely toxic to other organisms. o Alkaloids exhibit isomerism e.g. optical isomerism i.e L-ephedrine is 3.5 times more active than d-ephedrine • Chemical properties o Alkaloids are amines (may be primary, secondary, tertiary and quaternary) o Most alkaloids contain oxygen and are solid in nature e.g. Atropine. o Alkaloids are decomposed by heat, except Strychnine and Caffeine o Alkaloids react with acids to form salts o Dilute alkalis liberate most alkaloids from their salts e.g. NH3 o Some alkaloids are unstable when exposed to light and oxygen while others are not STEP 5: Naming of Alkaloids (35 minutes) • Alkaloids are named by various methods • Names of alkaloids end by "ine". These names may be derived from: o Generic plant name – Atropine from Atropa belladonna o Specific name of the plant – Cocaine from Erythroxylum coca o Names of loved ones e.g. Cathelenine o Common name of the plant – Ergotamine from ergot (rye) o Physiological action of the plant – Emetine producing emesis • Prefixes and Suffixes used in naming of alkaloids • Prefixes: o "Nor-" designates N-demethylation or N-demethoxylation, e.g. Norpseudoephedrine and Nornicotine. o "Apo-" designates dehydration e.g. Apomorphine. o "Iso-, pseudo-, neo-, and epi-" indicate different types of isomers • Suffixes: o "-dine" designates isomerism as Quinidine and Cinchonidine. o "-ine" indicates, in case of ergot alkaloids, a lower pharmacological activity e.g. Ergotaminine which is less potent than ergotamine STEP 7: Key Points (5 minutes) • Alkaloids are basic naturally occurring compounds containing one or more nitrogen atoms usually in a heterocyclic ring and have a marked physiological action on man or other animals • Alkaloids are produced by a large variety of organisms, including bacteria, fungi, plants, and animals and are part of the group of natural products • Alkaloids may occur in free state (e.g. as free bases), as salts (e.g. with organic acids), STEP 8: Evaluation (5 minutes) • What are alkaloids? • What are the functions of alkaloids in plants? • Mention physical properties of alkaloids? References Trease, G. E., Evans, W. C., & Evans, D. (2009). Trease and Evans pharmacognosy. London: Saunders. Joanne Barnes et al (2002), Herbal medicines 3rd Edition: Pharmaceutical Press Wallis, T. E. (2005). Textbook of pharmacognosy. New Delhi: CBS. Robbers, J. E., Speedie, M. K., Tyler, V. E., & Tyler, V. E. (1996). Pharmacognosy and pharmacobiotechnology. Baltimore: Williams & Wilkins. Heinrich, M., Kinghorn, A. D., Maizels, D., Gibbons, S., & Phillipson, J. D. (2012). Fundamentals of pharmacognosy and phytotherapy. Edinburgh: Churchill Livingstone/Elsevier. ← Previous TopicNext Topic →View all Basic Pharmacognosy topicsOpen Complete Full Notes PDF / OFFLINE NOTES Unataka kutumiwa notes hizi kupitia WhatsApp?Kwa notes zilizopangiliwa vizuri kwa kusoma offline au PDF, bonyeza kitufe hapa chini. Ujumbe wenye Level, Semester, Module na Topic utaandaliwa moja kwa moja.TUMIWA NOTES WHATSAPP WhatsApp: 255620339260

NTA Level 5 • Semester 2 • PST05210 Classification, Uses and Extraction of Alkaloids Basic Pharmacognosy • Source Session/Topic 19 Full source-text version: all educational wording from the extracted learning source is retained; only presenter/tutor metadata and web-layout noise are removed, while formatting is improved for readability. Session 19: Classification, Uses and Extraction of Alkaloids Total Session Time: 120 minutes Prerequisites • None Learning Tasks By the end of this session students are expected to be able to: • Classify alkaloids • List pharmacological actions and uses of alkaloids • Explain extraction, purification and isolation of alkaloids from powdered plants • Explain chemical tests for alkaloids Resources Needed: • Flip charts, marker pens, and masking tape • Black/white board and chalk/whiteboard markers • LCD projector and laptop SESSION OVERVIEW |Step |Time |Activity/ |Content | | | |Method | | |1 |05 minutes |Presentation |Introduction, Learning Tasks | |2 |35 minutes |Presentation |Classification of Alkaloids | |3 |15 minutes |Brainstorming |Pharmacological Actions and Uses | | | |Presentation |of Alkaloids | |4 |30 minutes |Presentation |Extraction, Purification and | | | | |Isolation of Alkaloids | |5 |20 minutes |Presentation |Chemical Tests for Alkaloids | |6 |10 minutes |Presentation |Key Points | |7 |05 minutes |Presentation |Evaluation | SESSION CONTENTS STEP 1: Presentation of Session Title and Learning Tasks (5 minutes) READ or ASK students to read the learning objectives and clarify ASK students if they have any questions before continuing. STEP 2: Classification of Alkaloids (40 minutes) • Alkaloids differ widely in their botanical and biochemical origin, in chemical structure and their pharmaceutical action • Therefore, there many different systems for classification of alkaloids • Major classification systems include o On the basis of basicity ▪ Alkaloids may be classified into weak bases e.g. caffeine, strong bases e.g. atropine, amphoteric alkaloids e.g. phenolic alkaloids like morphine and neutral alkaloids e.g. colchicine o Biological origin o Chemical structure o Biosynthetic pathway • Classification based on chemical structures (the Hegnauer’s classification) is more useful and practical • By the Hegnauer’s Classification, alkaloids are grouped into: o Typical/True Alkaloids ▪ They are derived from amino acids and contain a nitrogen in a heterocyclic ring e.g. Atropine ▪ They are toxic ▪ Show a wide range of physiological activity ▪ They are almost invariably basic ▪ They are biosynthesized from amino acids ▪ They normally occur in the plant as salt of an organic acid ▪ Colchicine and quaternary alkaloids are not basic in nature and do not have heterocyclic ring in their structures ▪ They are divided into the following groups based on their ring structures • Pyrrole and Pyrolidine e.g. hygrine, strychnine • Pyrrolizidine e.g. symphitine, echimidine etc. • Pyridine and Piperidine e.g. Nicotine etc. • Tropane (Piperidine/N-methyl-pyrrolidine) e.g. hyoscyamine, atropine, etc. • Quinoline e.g. quinine etc. • Isoquinoline e.g. emetine, morphine, codeine, etc. • Aporphine (reduced isoquinine/ naphthalene) e.g. boldine • Quinolizidine e.g. cytisine etc • Indole or Benzopyrrole e.g. Ergometrine, ergotamine etc. • Indolizidine e.g. Castanospermine etc. • Imidazole or Glyoxaline e.g. pilocarpine • Terpenoid e.g. Aconitine o Proto-alkaloids/Atypical Alkaloids ▪ Derived from amino acids but do not contain nitrogen in the heterocyclic ring ▪ They are also called biogenic amines ▪ They are simple amines biosynthesized from amino acids and are basic ▪ Examples of proto-alkaloids include mescaline, ephedrine, erythromycin, taxol o Pseudoalkaloids ▪ They are not derived from amino acids ▪ There are two major series in this class: • The steroidal alkaloids e.g. Conessine • The terpenoid alkaloids e.g. Purines, Caffeine, Theophylline and Theobromine [pic] STEP 3: Pharmacological Actions and Uses of Alkaloids (15 minutes) |Activity: Brainstorming (5 minutes) | | | |Ask students to brainstorm on the following question: | | | |What are the uses of alkaloids? | | | |ALLOW few students to respond? | | | |WRITE their responses on the flip chart/ board | | | |CLARIFY and SUMMARIZE by using the content below | • Alkaloids have marked pharmacological activities o Analgesics and narcotics e.g. morphine and codeine o CNS stimulants e.g. caffeine and strychnine o Anticancer activity e.g. vincristine, vinblastine and taxol o Mydriatics e.g. atropine o Anti-asthmatic activity e.g. ephedrine o Antitussive e.g. codeine o Expectorant effect e.g. lobeline o Anti-hypertensive e.g. reserpine o Smooth muscle relaxants e.g. atropine and papaverine o Skeletal muscle relaxants e.g. d-tubocurarine o Anthelmintic activity e.g. pelletierine and arecoline o Antiparasitic action e.g. quinine and emetine o Antibacterial activity e.g. berberine STEP 4: Extraction, Purification and Isolation of Alkaloids (25 minutes) • Stas-Otto Method o This technique involves the distribution of alkaloid bases between acid or aqueous solution and immiscible organic solvent o First Stage ▪ Powdered plant material is moistened with water and mixed with alkali like sodium and potassium carbonate, ammonia, calcium hydroxide. A paste is made with water, dried and re-powdered • The lime combines with acid, tannins and other phenolic substances and sets free the alkaloids o Second Stage ▪ The free alkaloids are extracted by hot continuous percolation with chloroform or other organic solvent • The free alkaloids dissolve together with other substances soluble in solvent o Third stage ▪ Chloroform solution is agitated with successive portions of dilute sulphuric acid separating the aqueous layer before adding the next portion ▪ The alkaloids are converted into alkaloidal sulphates, which being soluble in water, pass into the aqueous layer o Fourth Stage ▪ The mixed aqueous liquid is made alkaline with ammonia, and precipitates that form are collected, washed with water and dried • Ammonia decomposes the alkaloidal sulphates forming ammonium sulphates, soluble in water and the free alkaloid which being practically insoluble in water is precipitated • Volatile alkaloids are extracted by steam distillation i.e. Plant material + water + Fixed alkali [pic] steam containing alkaloids Heat received in acidic solution • Alkaloids are purified by; o Direct crystallization from solvent o Steam distillation o Chromatography techniques o Gradient pH techniques STEP 5: Chemical Tests for Alkaloids (20 minutes) • Alkaloids can be identified by chemical tests •