Cultivation of medicinal plants – PST05210 Basic Pharmacognosy
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