ORAL EXAM

 

                                                       

                                ORAL EXAMINATION: BASIC PHARMACOGNOSY

                                                              PST NTA L5

1.      Explain the differences between the internal structure of monocot root and stem

MONOCOT ROOT

•      The Rhizodermis or Epiblema

§  Outermost layer of the root

§  Single row of parenchyma cells, no intercellular space

§  Stomata and cuticle are absent

§  Root hairs are always unicellular

§  The key function of rhizodermis is protection of the inner tissues of the root

·         The Cortex

§  The cortex is made of only one type of tissue (parenchyma)

§  Has many layers of parenchyma cells with lot of intercellular spaces

§  Cortical cells are generally oval or rounded in shape; chloroplasts are absent

§  The cells are living and possess leucoplasts

§  The inner most layer of the cortex is endodermis and is composed of single layer of barrel shaped parenchymatous cells

§  The function of cortical cells is storage

§  Endodermis (innermost layer of cortex) forms a complete ring around the stele (tissues inside endodermis)

·         There is a band-like structure made of (thickened with) suberin present in the radial and transverse walls of the endodermal cells

·         The band is called Casparian strips

·         The endodermal cells opposite to the protoxylem elements, are thin-walled without Casparian strips

·         These cells are called passage cells and their function is to transport water and dissolved salts from the cortex to the xylem

·         Water cannot pass through other endodermal cells due to Casparian strips (blocking effect)

·         The main function of Casparian strips in the endodermal cells is to prevent the re-entry of water into the cortex once water enters the xylem tissue

·         Vascular System (Stele)

§  Vascular tissues are in radial arrangement with many protoxylem groups

§  This arrangement of xylem is called polyarch and the xylem is in exarch condition

§  The tissue present between the xylem and the phloem, is called conjunctive tissue

 

·         The Pith

§  The central portion 

§  It consists of thin walled parenchyma cells with intercellular spaces

§  These cells are filled with abundant starch grains

MONOCOT STEM

·         Epidermis

§  It is the outermost layer of the stem made up of single layer of parenchymatous cells and covered with a thick cuticle in some plants

§  Consists of few stomata

·         Hypodermis

§  Is made of few layer of sclerenchymatous cells lying below the epidermis

§  This layer gives mechanical strength to the plant 

·         Ground Tissue

§  Consists of cells inner to the hypodermis

§  Is not distinguished into zones like the dicot stem

§  The cells contain reserve food material e.g. starch

§  Contains the vascular bundles

§  Carry out gaseous exchange function

·         Vascular Bundles

§  Vascular bundles are scattered in the ground tissue

§  The vascular bundles are conjoint, collateral, endarch and closed

§  Vascular bundles are skull shaped

§  Xylem

§  Forms the woody part of the plant

§  Carries water and minerals up the plant

§  Dead at functional maturity

§  Phloem

§  Consists of sieve tubes and companion cells

§  Phloem parenchyma and phloem fibres are absent

 

 

 

 

 

 

 

 

 

 

 

 

2.       Explain the classification of the flower

o  Based on presence of male, or female or both reproductive structures

§  Perfect/Bisexual/Hermaphrodite Flower

·      These flowers bear both male and female reproductive structures

§  Imperfect/Unisexual Flower

·      Bears male or female reproductive structures

·      Staminate flower (male flower)

·      Pistillate/carpellate flower (female flower)

o Based on presence or absence of any structure

§  Complete Flower

·         Flowers bear sepals, petals, pistils, and stamens

§  Incomplete Flowers

·         Sepals, petals, pistils, or stamen is missing

o Based on the number of flowers

§  Simple flowers

·         One flower on an axis (receptacle)

o  Compound flowers or Inflorescence

·                       Have more than one flower on the receptacle or axis

·         The axis forms the rachis and florets are attached on pedicels

o  Inflorescence are subsequently classified based on pattern of arrangement into;

·         Single inflorescence –same pattern of arrangement of florets

·         Compound inflorescence –complex pattern

·         Main inflorescences include;

o   Raceme (or racemose)

o   Spadix

o   Spike

o   Corymb

o   Umbel

o   Head

o      Based on flora variations

§  Flowers are grouped according to the placement of floral parts on the receptacle into;

·         Hypogynous flowers

o   Sepals, petals, and stamens are attached to a convex or conical receptacle at the base of the ovary

o   The ovary is called superior and the perianth is inferior or hypogynous

·         Perigynous flowers

o   Sepals, petals, and sometimes stamens borne on the edge or margin of the receptacle and appear to form a cup around the pistil

·         Epigynous flowers

o   Sepals, petals, and stamens appear to arise from the top of the ovary

o   The ovary is inferior and the perianth is superior or epigynous

o      Based on floral symmetry

§  Regular or Actinomorphic flowers

·         Flowers divisible into symmetrical halves by more than one longitudinal plane through the axis

§  Irregular or Zygomorphic flowers

·         Flowers divisible only by a single plane into two mirror-image halves

§  Asymmetrical flowers

·         Flowers indivisible into identical or mirror-image halves on any plane

 

3.      Mention six advantages of Asexual propagation

1. There is no variation between the plant grown and

plant from which it is grown. As such, the plants are

uniform in growth and yielding capacity. In case of

fruit trees, uniformity in fruit quality makes harvesting

and marketing easy.

2. Seedless varieties of fruits can only be propagated

vegetatively e.g. grapes, pomegranates and lemon.

3. Plants start bearing earlier as compared to seedling

trees.

4. Budding or grafting encourages disease-resistant varieties

of plants.

5. Modifying influence of root-stocks on scion can be

availed of.

6. Inferior or unsuitable varieties can be over-looked.

4.      Explain storage of crude drugs

a.      During storage, drugs are affected by physicochemical and biological factors

b.      Physicochemical factors include light, moisture, temperature and air oxygen while biological factors include fungi, bacteria, worms, insects and mites

c.       Long storage is not recommended, due to deterioration except in cascara bark. Active constituents decrease massively

d.      Drugs should be stored in sealed containers in cool dark places

e.      Generally, the permissible moisture content is 8% or below.

f.        Air dried drugs are always liable and are easily attacked by insects and other pests, so they should be frequently examined during storage or may require sterilization by ethylene oxide or methyl chloride before storage

 

5.      a. mention three medicinal plants which require slowly drying at moderate temperature due to enzymatic desired after collection

vanilla pods, gentian roots and cocoa seeds

 

b. 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

6.      Extraction is the method of removing active constituents from a solid or liquid by means of liquid solvent.

The separation of medicinally active portions of plant or animal tissues from the inactive or inert components by using selective solvents.

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.

(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

 

7.      Type of extracts

Dry extract (Tab, cap.) E.g. belladonna extract

Soft (Ointment, suppository) E.g. glycerrhiza extract.

Liquid: As tincture.

 

8.      Methods of extraction (45 minutes)

Types of extractions are: Infusion, Decoction, Digestion, Maceration, Percolation, Continues hot extraction, Supercritical fluid extraction, counter current extraction, Microwave assisted extraction, Ultra sonication-Assisted Extraction:

Infusion

Infusion: Fresh infusions are prepared by macerating the crude drug for a short period of time with cold or boiling water. These are dilute solutions of the readily soluble constituents of crude drugs.

Types of Infusion:

Fresh Infusion: e.g. Infusion of orange }

Concentrated Infusion: e.g. concentrated infusion of Quassia

Decoction

Decoction: In this process, the crude drug is boiled in a specified volume of water for a defined time; it is then cooled and strained or filtered. This procedure is suitable for extracting water-soluble, heat stable constituents. e.g. Tea , Coffee

Digestion

This is a form of maceration in which gentle heat is used during the process of extraction. It is used when moderately elevated temperature is not objectionable. The solvent efficiency of the menstruum is thereby increased. e.g. Extraction of Morphine

 

 

Maceration

Maceration: In this process solid ingredients are placed in a stoppered container with the whole of the solvent and allowed to stand for a period of at least 3 days (3 - 7 days) with frequent agitation, until soluble matter is dissolved. The mixture is then strained (through sieves / nets), the marc pressed and the combined liquids clarified (cleaned by filtration) or by decantation, after standing.

Types of maceration

Simple maceration: for organized and unorganized Crude drug e.g. i) Tincture of Orange ii) Tincture of Lemon iii) Tincture of Squill

Double maceration: Concentrated infusion of orange

Triple maceration: The maceration process may be carried out with help of heat or stirring e.g. i) Concentrated infusion of Quassia ii) Concentrated infusion of Senna

 

9.      Outline three (3) types of fruits

a.      Simple fruits

                                                              i.      Fruits formed from one ovary in one flower

b.      Aggregate fruits

                                                              i.      Fruits formed from more than one ovary of one flower

c.       Multiple fruits

                                                              i.      Fruits formed from an inflorescence and include accessory structures

10.  Outline six simple succulent Fruits

a.      Berries

                                                              i.      Have soft epicarp and fleshy mesocarp and endocarp

b.      Hesperidiums

                                                              i.      Berries with a thicker skin containing oils

c.       Pepos

                                                              i.      Berries with a comparatively thick exocarp or rind

d.      Drupes/stones

                                                              i.      Have edible exocarp and fleshy mesocarp and inedible, hard stone-like endocarp

 

e.      Pome

                                                              i.      A fleshy fruit with mature ovary and accessory structures e.g. petals, sepals and receptacle

f.        Polydrupes

                                                              i.      Are soft aggregate fruits (fusion of several drupes) e.g. strawberries, blackberries etc.

11.  Outline four Simple dry indehiscent fruits and two simple dehiscent fruits

a.      Simple dry indehiscent fruits

                                                              i.      Samara

1.      A winged fruit

                                                             ii.      Achene

1.      A hard dry fruit with one seed which almost feels the pericarp but attached loosely

                                                           iii.      Nuts

1.      Simple dry fruit similar to achenes, but formed from two or three carpels. Pericarp is relatively hard and heavy

                                                           iv.      Caryopsis

1.      It is a simple, dry fruit in which the testa and pericarp are fused

b.      Simple dry dehiscent fruits

                                                              i.      Legumes

1.      Are dry fruits which split along both dorsal and ventral sutures to release their seeds e.g. Cassia angustifolia 

                                                             ii.      Follicles

1.      Dry fruits which splits along inner suture only e.g. strophanthus

12.  Outline seven External structures of a seed

a.      Seed coat

                                                              i.      Most seeds have two seed coats

                                                             ii.      Testa (the outer seed coat)

1.      Outer most protective layer of the seed –form the seed coat

2.      Protects the seed

3.      Thickness varies with type of seed

                                                           iii.      Tegmen

1.      The inner seed coat

b.      Funicle or stalk

                                                              i.      A structure that attaches the seed to the placenta

c.       Micropyle

                                                              i.       An opening that marks position of the radicle

d.      Hilum

                                                              i.      Scar left by the funiculus (attachment to the embryo)

e.      Raphe

                                                              i.      Fibrovascular tissue formed by adhesion of funicle and testa

f.        Aril

                                                              i.      Expansion of placenta or funicle over the surface of the seed

                                                             ii.      Formed in some seeds

g.      Elaiosome

                                                              i.      Fleshy structures rich in lipids and proteins attached to the seed

h.      Caruncle or Strophiole

                                                              i.      A structure that arises from the testa near the hilum

13.  With their functions Mention organelles found in a plant cell

·      The Nucleus

o  Spherical body containing a nucleolus

o  Surrounded by the nuclear membrane

o  Contains DNA (genetic material in chromosomes)

·      Nucleolus

o  An organelle within the nucleus where ribosomal RNA is produced

o  It controls many of the functions of the cell (by controlling protein synthesis)

·      Centrosome

o  It is a small body located near the nucleus that forms and organizes microtubules

o  Microtubules are important in cell division (mitosis)

·      Ribosomes

o  Are small organelles composed of RNA-rich cytoplasmic granules that are sites of protein synthesis

·      Endoplasmic Reticulum

o  Endoplasmic reticulum is a system of interconnected, membranous, infolded and convoluted sacks located in cytoplasm (the ER is continuous with the outer nuclear membrane)

o  It transports materials through the cell and produces proteins

o  Smooth Endoplasmic Reticulum are smooth (i.e. no ribosomes on surface)

§ Contains enzymes and produces and digests lipids (fats) and membrane proteins

·      Golgi Complex: (i.e. Golgi apparatus or Golgi body)

o  Is a flattened, layered, sac-like organelle that looks like a stack of pancakes, located near the nucleus

o  It packages and transports materials (proteins and carbohydrates) to different locations inside/outside cell

·      Mitochondria

o  Spherical to rod-shaped organelles with a double membrane that generates energy for the cell

·      Plastids

o  Are structures responsible for photosynthesis, storage of products like starch and for the synthesis of many classes of molecules such as fatty acids etc. needed as cellular building blocks and/or for the function of the plant. There several types; proplastids, etioplasts, chloroplasts, chromoplasts, leucoplasts and leucoplasts specialized for different functions in the plant body.

 

 

·      Vacuoles

o  Are regions bound by membrane and filled with cell sap and surrounded by the tonoplast

o  In mature living cells may compose 90 - 95% of cell volume

o  Storage site for variety of (ergastic) substances such as:

§ Water

§ Enzymes and other proteins

§ Water-soluble pigments (e.g. red and blue anthocyanins)

§ Toxic alkaloids, tannins

§ Lipids

§ Crystals (calcium oxalate, calcium carbonate, silicon dioxide)

§ Organic acids (oxalate, malate)

14.  Describe the following internal structure of the leaf

oPalisade Parenchyma (Palisade Mesophyll) (5 points)

§  Palisade parenchyma lies beneath the adaxial epidermis

§ Palisade mesophyll may be present below both surfaces or occur only below the upper epidermis

§ Consists of vertically elongated cylindrical cells in one or more layers

§ Cells are compactly arranged with the chloroplasts close to the walls of the cell

§ Main function is photosynthesis

 

o   Spongy Mesophyll (4points)

§  Lies below the palisade mesophyll, with irregularly shaped, loosely arranged cells

§  Contain fewer chloroplasts than palisade mesophyll

§  Spongy cells facilitate exchange of gases with the help of air spaces

§  The pores or stomata of the epidermis open into sub stomatal chambers, connecting to air spaces between the spongy layer cells

 

15.  Outline five characteristics of flower pollinated by the following

                                                              i.      Flowers pollinated by insects have bright colours, sweet fragrance and produce nectar

                                                            ii.      Flowers pollinated by wind have large stigmas, no or little fragrance, and non- sticky pollens

                                                          iii.      Flowers pollinated by birds are log tube shaped, have bright red or yellow colours, and with no fragrance 

                                                          iv.      Flowers pollinated by mammals have white flowers with strong fruity smell and open at night

                                                            v.      Flowers pollinated by water may have pollens which floats on water

16.  Outline factors (exogenous and endogenous factors affecting cultivation of medicinal plants

 

·      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 produced are greatly affected by amount of sunlight

·         Long day:  menthone, menthol and menthofuran traces

·         Short day:  menthofuran is a main component

§  Belladonna, Stramonium and Cinchona ledgeriana full sunshine gives high content of alkaloids than does shade

§  Other species:  produce more active constituents at night e.g. Nicotiana

o   Radiation

§  Type of radiation plants receive e.g.  Ocimum basilicum – plants grown in glass houses have less phenols and terpenoids in the leaves (flavonoids, volatile oils)

o   Latitude and Altitude

§  Gentian produce bitter constituents when grown in higher altitude

§  Thyme and Peppermint produce less constituents when grown in higher altitude

§  Coconut needs a maritime climate

§  Sugar cane is lowland plant

§  Tragacanth, Cinchona succirubra require elevation

§  Tea requires (1000-2000 M), coffee (800 – 1800 M), and cocoa (100 – 200 M)

§  Peanut & olive grown in the subtropics produce a higher unsaturated fat content.

 

o   Soil Condition

§  Soil character, composition, permeability, porosity all effect growth of medicinal plants e.g.

·         Chalky soil lead to poor of Digitalis

·         Crop rotation improves nutrient content of soils

·         pH of soil affects inorganic compounds of soil

 

· Genetic (Endogenous) Factors

o      Allelopathy

§ Allelopathy is the constant effect which living organisms exert on each other, which may be either beneficial or harmful

§  Different plants growing together affect each other in terms of:

·         Germination rate

·         Leaf development

·         Fruit maturation

·         Chemical constituents produced

§ It is transmitted between plants in a number of ways

·         Exhalation of leaves

·         Root secretions

·         Extractions from fallen leaves into the soil

o Mutual dependant organisms (beneficial) symbiosis e.g.  Urtica dioica

o  Destructive allelopathy antibiosis e.g.  Belladonna growth is inhibited when cultivated next to mustard

·      Post-Cultivation Factors

o   Drying & storage methods of drugs

17.  Explain the following classification of medicinal plant; Alphabetical, Taxonomic, Morphological, Pharmacological or therapeutic, Chemical or Biogenetic

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

·         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.

• 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

 

18.  Outline general conditions and techniques when drying medicinal plants as follows

a.      For Leaves/Herbs: ( four points)

                                                              i.      Temperature should be between 40-50º C to maintain good colour

                                                             ii.      Leaves or herbs should normally be destalked first

                                                           iii.      They are best dried for short periods of time only to prevent shrivelling and discoloration

                                                           iv.      They may be bleached through the drying process

b.      For Roots/Rhizomes:( five points)

                                                              i.      They should be washed

                                                             ii.      They should be sliced

                                                           iii.      They should be dried between at temperatures between 30-65ºC

                                                           iv.      Too high temperature may prevent further drying in deeper parts of the drug

                                                             v.      Thick organs may require long periods of drying (10days-3weeks) to avoid mould growth

c.       For Flowers;(two points)

                                                              i.      Flowers are normally destalked before drying

                                                             ii.      Flowers may also be bleached when dried 

d.      Volatile oil-containing drugs;(two points)

                                                              i.      Are air-dried at very low temperature to avoid volatilization of oil contents

                                                             ii.      They should be dried separately from other herbs

e.      Fruits and Seeds;(five points)

                                                              i.      They are normally partially dry before harvesting

                                                             ii.      They may be air-dried afterwards

                                                           iii.      Seeds are normally separated from the fruits before drying

                                                           iv.      Fruits are normally left whole

                                                             v.      Some fruits (cardamom) rupture due to excessive heat.

 

 

19.  Explain four process of drying

                                                              i.      Air Drying

1.      Sun Drying

a.      Is done when drugs are not adversely affected by excessive sunlight.

b.      Drugs are dried in thin layers and tuned over occasionally

c.       Drugs dried in this way include clove and cardamom

2.      Shade Drying

a.      Done when sunlight causes discoloration and warping/shrivelling of the drugs e.g. cinnamon

                                                             ii.      Artificial Drying

1.      Artificial source of heat is used in the drying process

2.      Drying in the oven (oven drying) is the commonest methods used in artificial drying

3.      Artificial drying is more accepted and more rapid than air-drying

4.      Artificial drying is more suitable for use in the wet weather

5.      Drying temperature is governed by constituents

a.      Generally, leaves, herbs and flowers are dried between 20-40^oC, barks and roots: 40-65^oC

6.      When done rapidly, the drugs retain colour and aroma

 

                                                           iii.      Vacuum Drying

1.      It is also done in oven, but at low temperature

2.      Low pressure ensures rapid and complete drying

3.      It is an expensive method and thus reserved for expensive drugs or drugs which cannot be sufficiently dried by other methods

                                                           iv.      Lyophilisation

1.      Involves freezing of the drug and then evaporation under low pressure

2.      Very suitable method for drugs that are very sensitive to heat

3.      The resulting product is a fine powder

4.      This method is used for drying biological fluids, enzymes, proteins and royal jelly

 

 

 

 

 

 

 

20.  Explain the differences between DICOT stem and roots

DICOT STEM

·         Epidermis

§  It consists of a single layer of parenchymatous rectangular cells

§  Epidermal cells are compactly arranged without intercellular spaces

§  Epidermis is covered on the outside by cuticle made up of waxy substance

§  The cuticle checks/controls transpiration

§  Stomata may be present at irregular intervals

§  A large number of multicellular hairs occur on the epidermis

·         Cortex

§  Cortex lies below the epidermis

§  The cortex is differentiated into three zones

§  The first zone (Hypodermis)

·         Lies below the epidermis, consists of a few layers of collenchyma cells

§  The second zone

·         Lies inner to the hypodermis

·         Consists of a few layers of collenchyma cells

·         Some resin ducts also occur in this zone

 

• The third zone
• Consists of parenchyma cells
• The innermost layer of the cortex is the endodermis
• Made of barrel shaped cells arranged compactly without intercellular spaces
• Rich in starch grains, hence “starch sheath”
• In most dicot stems no casparian strips

 

• The Stele
• In the central part of the stem inner to the endodermis
• It consists of pericycle, vascular bundles and pith
• Vascular bundles are arranged in a ring around the pith
• Pericycle
• Layers of cells between endodermis and vascular bundles

 

• Vascular Bundles
• Consist of xylem, phloem and cambium
• Xylem and phloem in stem occur together to form the vascular bundles
• These vascular bundles are wedge shaped
• The vascular bundle is conjoint, collateral, open and endarch
• Phloem
• Consists of sieve tubes, companion cells and phloem parenchyma
• Phloem conducts organic food materials from the leaves to other parts of the plant body
• Cambium
• Consists of brick shaped and thin walled meristematic cells
• Form new cells during secondary growth
• Xylem
• Consists of xylem fibres, xylem parenchyma, vessels and tracheids
• Vessels are thick walled and arranged in a few rows
• Conducts water and minerals from the root to the other parts of the plant body
• Pith (medulla)
• It is the large central portion of the stem
• It is composed of parenchyma cells with intercellular spaces
• The pith extends between the vascular bundles and form primary medullary rays
• These extensions of the pith between the vascular bundles are called
• It stores food

 

 

 

 

 

 

DICOT ROOT

 

• Rhizodermis or Epiblema
• Outermost layer aka rhizodermis (epidermis in stems) made of a single layer of parenchyma cells which are arranged compactly without intercellular spaces, with no stomata or cuticle
• Root hair is always single celled
• Protects inner tissues of the root
• The Cortex
• Consists of only parenchyma cells loosely arranged with intercellular spaces to make gaseous exchange easier
• These cells may store food reserves
• The cells are oval or rounded in shape
• Sometimes are polygonal due to mutual pressure
• Cortical cells are devoid of chloroplasts but starch grains are stored in them
• The cortical cells also possess leucoplasts
• Inner most layer of the cortex is endodermis
• Endodermis is made up of single layer of barrel shaped parenchymatous cells
• Stele is completely surrounded by the endodermis
• The radial and the inner tangential walls of endodermal cells are thickened with suberin
• Casparian strips
• Casparian strips are absent in the endodermal cells located opposite to the protoxylem elements
• These thin-walled cells without Casparian strips are called passage cells through which water and mineral salts are conducted from the cortex to the xylem elements
• Water cannot pass through other endodermal cells due to the presence of Casparian thickenings

 

 

• The Stele
• Include all the tissues present inside endodermis
• The stele includes pericycle and vascular tissues
• The Pericycle
• Pericycle is generally a single layer of parenchymatous cells found inner to the endodermis
• It is the outermost layer of the stele
• Lateral roots originate from the pericycle
• Thus, the lateral roots are endogenous in origin
• The Vascular Tissues
• Vascular tissues are in radial arrangement
• Xylem and phloem are separated by a conjunctive tissue
• If conjunctive tissue is composed of parenchymatous tissue then, the xylem is in exarch condition
• If number of protoxylem points is four, then, the xylem is called tetrarch
• Each phloem patch consists of sieve tubes, companion cells and phloem parenchyma
• Metaxylem vessels are generally polygonal in shape but in monocot roots they are circular

21.  Outline ten parts that made up a typical flower

 

o  Peduncle –the flower stalk

o  Receptacle –bears the floral organs

§ Forms the hypanthium if elongated below the calyx

§ If below the ovary it is the gynophore or stalk of the ovary

o  Calyx –made up of sepals (to protect young flower bud)

§ Polysepalous if sepals are separate

§ Gamosepalous if sepals are fused

o  Corolla –made up of petals (often colourful)

§  Polypetalous if petals are separate

§  Gamopetalous if petals are fused

o      Perianth –formed from sepals and petals together

o      Stamen –male reproductive structures of the flower

§ Made up of anther and filaments (produce pollen grains)

§ Monadelphous if stamens are fused

§ Diadelphous if stamens are separate

o  Pollen -Grains containing the male gametes

o  Pistil –female part of the flower

§ Made up of stigma, style and ovary

o  Carpel –A unit of compound pistil or ovary

o  Ovule –bears the female gametes, located in the ovaries

o  Gynoecium –one or more pistils (carpel, ovary, ovules, female gametes)

Androecium –one or two whorls of stamens (filament, anther, pollen grains,

22.  What is the difference between monocot and dicot stem

 

 

 

23.  Outline four classification of volatile oil based on extraction method

 

 

§  Concretes

·         Uses solvent e.g. hexane and waxes or resins to contact the plant materials and then the solvent removed by gent heating e.g. jasmine oil

§  Pomades

·         Obtained by enfleurage (hot or cold) e.g. oils from flowers

§  Resinoids

·         Extraction with resinous materials i.e. to prolong effect of fragrance

§  Absolutes

·         Remains after alcoholic extraction from pomades or concretes

24.  List eight characteristics of glycosides

1. Glycosides are soluble in water but insoluble in organic solvents

                                                              i.      The glycone part is water soluble but insoluble in the organic solvents

                                                            ii.      The aglycone part is water insoluble but soluble in the organic solvents

                                                          iii.      Some glycosides are soluble in alcohol

2. Glycosides are ccolorless (except flavonoid- yellow, anthraquinone-red or orange)
3. They are solid, amorphous and nonvolatile
4. They give a positive reaction with Molisch's and Fehling's solution test (after hydrolysis).
5. Most glycosides have bitter taste
6. They are oodorless except saponin (glycyrrhizin).
7.  Glycosides with lots of sugars have increased solubility in water
8. Glycosides hydrolyzed by using mineral acids and temperature or by using enzymes

 

25.  With examples outline eight methods of vegetative propagation

By the development of bulbs (e.g. squill); corms (e.g. colchicum); tubers (e.g. jalap and aconite); or rhizomes (e.g. ginger).

 

 By division, a term usually applied to the separation of a plant which has a number of aerial stems or buds, into separate parts each having roots and a growing point. This method may be used for althaea, rhubarb, gentian and male fern.

 

 By runners or offsets (e.g. chamomile and the mints).

 

 By suckers or stolons (e.g. liquorice and valerian).

 

By cuttings or portions of the plant severed from the plant and capable of developing roots. Success by this method has been extended to a large number of plants by the use of rooting hormones  and by the employment of mist propagation.

By layers. A layer is a branch or shoot which is induced to develop roots before it is completely severed from the parent plant. This is done by partly interrupting the food supply by means of a cut or ligature and embedding the part. Alternatively the slit portion of the branch is enclosed in moist peat, surrounded by moss, and the whole enclosed in polythene. This method has been used successfully for the propagation of cascara.

By grafting and budding. Grafting is an operation in which two cut surfaces, usually of different but closely related plants, are placed so as to unite and grow together. The rooted plant is called the stock and the portion cut off the scion or graft. In Guatemala young Cinchona ledgeriana scions are grafted on Cinchona succirubra root-stocks, eventually giving a tree which produces bark rich in the alkaloid quinidine. Grafting of female scions of Myristica fragrans on male stocks may be used to increase the proportion of fruit-bearing trees in the plantation. The method has been used considerably in phytochemical research to study sites of synthesis of metabolites etc. Budding consists of the introduction of a piece of bark bearing a bud into a suitable cavity or T-shaped slit made in the bark of the stock. Budding is largely used for Citrus species, selected strains of sweet orange, for example, being budded on sour stocks. 8. By fermentation. This process applies particularly to the production of moulds and bacteria, and is extensively used in the manufacture of antibiotics, lysergic acid derivatives and some vitamins.

 By inoculation. Specific to ergot whereby the spores of the fungus are artificially cultured and injected into the rye heads by special machines,

 

 

26.  Explain evaluation of Crude drugs

ORGANOLEPTIC EVALUATION

Organoleptic evaluation means the study of drugs using organs of senses. It refers to the methods of analysis like colour, odour, taste, size, shape, and special features, suchas: touch, texture,

MICROSCOPICAL EVALUATION

Microscopic evaluation is indispensable in the initial identification of herbs, as well as in identifying small fragments of crude or powdered herbs, and in the detection of adulterants (e.g. insects, animal faeces, mold, fungi, etc.) as well as identifying the plant by characteristic tissue features. The characteristic features of cell walls, cell contents,

starch grains, calcium oxalate crystals, trichomes, fibres,vessels, etc. have been studied in details

CHEMICAL EVALUATION

The chemical evaluation includes qualitative chemical tests,quantitative chemical tests, chemical assays, and instrumental analysis. The isolation, purification, and identification

of active constituents are chemical methods of evaluation. Qualitative chemical tests include identification tests for various phytoconstituents like alkaloids, glycosides, tannins,

PHYSICAL EVALUATION

In crude plant evaluation, physical methods are often used to determine the solubility, specific gravity, optical rotation,viscosity, refractive index, melting point, water content,

degree of fibre elasticity, and other physical characteristics of the herb material

BIOLOGICAL EVALUATION

The plant or extract can then be evaluated by various biological methods to determine pharmacological activity,potency, and toxicity. The biological evaluation would serve

better than the physical and chemical evaluation for drugs that could not be satisfactorily assayed by these last two methods.

 

 

27.  With examples, mention twelve (12) groups  of TYPICAL/TRUE alkaloids based on their ring structures

a.      Pyrrole and Pyrolidine e.g. hygrine, strychnine

b.      Pyrrolizidine e.g. symphitine, echimidine etc.

c.       Pyridine and Piperidine e.g. Nicotine etc.

d.      Tropane (Piperidine/N-methyl-pyrrolidine) e.g. hyoscyamine, atropine, etc.

e.      Quinoline e.g. quinine etc.

f.        Isoquinoline e.g. emetine, morphine, codeine, etc.

g.      Aporphine (reduced isoquinine/ naphthalene) e.g. boldine

h.      Quinolizidine e.g. cytisine etc

i.        Indole or Benzopyrrole e.g. Ergometrine, ergotamine etc.

j.        Indolizidine e.g. Castanospermine etc.

k.       Imidazole or Glyoxaline e.g. pilocarpine

l.        Terpenoid e.g. Aconitine

 

28.  With examples give the classification of Glycosides

Glycosides can be classified base on the following basis:

§  Based on therapeutic effects

·         Cardiac glycosides, Laxative glycosides etc.

§  Based on glycone moiety

·         Rhamnosides, glucorhamnosides, rhamnoglucosides etc.

§  Based on glycosidic linkage/bond

·         O-glycosides, s-glycosides, N-glycosides, C-glycosides

§  Based on chemical nature of the aglycone

·         Alcoholic and phenolic glycosides

·         Anthraquinone glycosides

·         Coumarin glycosides

·         Cyanogenic glycosides

·         Flavanoidal glycosides

·         Steroidal glycosides

·         Thioglycosides

29.  Factors affecting storage of the crude drug

Moisture leading to decomposition of constituents of some crude drugs if not stored properly, example digitalis leaf absorb moisture which may be sufficient to activate enzymes present in the leaves and bring about decomposition of the glycosides

Other drugs, such as powdered squill, which contain mucilage quickly absorb moisture and become a sticky mass

An increase in temperature, in combination with moisture, may accelerate enzyme activity; a large temperature rise will obviously lead to a loss of volatile constituents (e.g. essential oils from dried plant material)

 

Direct sunlight can cause decomposition of certain constituents (e.g. vitamins in cod-liver oil) as well as producing a bleaching of leaves and flowers.

Oxygen assists in the resinification of volatile oils and in the rancidification of fixed oils hence these crude drugs should be stored in airtight container

30.  Importance of processing medicinal plants

To improve the purity of the plant part being employed

Reduce drying time

Prevent damage from mould,other microorganisms and insects

Detoxify indigenous toxic ingredients; and

Enhance therapeutics efficacy

31.  Classification of the leaf

Based on arrangement on the stem

ü  Alternate – is characterized by the presence of one leaf at each node and all leaves together make a spiral path on the axis

ü  Opposite – When two leaves are placed at the same node and are opposite to one another

ü  Whorled - When more than two leaves are present in a single node and are arranged in a circle

ü  Rosulate –the leaves arrange themselves in a ring-like pattern around the stem

  Divisions of the lamina

ü  Simple leaves: A leaf which has only one leaf blade or lamina is called a simple leaf. It may be stipulate or exstipulate, petiolate or sessile, but always possess axillary bud in its axil. It may have an undivided lamina or may be lobed, e.g. vasaka, digitalis, eucalyptus, datura, carica, castor and argemone.

ü  Compound leaves: A compound leaf consists of more than one leaf blade or the lamina, the compound leaf is divided into several segments called leaflets or pinnae, e.g. senna, tamarind, acacia

The apex of the leaf may be one of the following kinds:

ü  Obtuse: Rounded tip, i.e. banyan.

ü   Acute: When it is pointed to form acute angle, but not stiff, i.e. hibiscus.

ü  Acuminate: Pointed tip with much elongation,peepal.

ü   Recurved: When the apex is curved backward.

ü  Cuspidate: With spiny tip like date palm.

ü   Mucronate: Rounded apex ending abruptly in a short point i.e vinca, ixora.

ü   Retuse: Broad tip with slight notch, i.e. pistia.

ü   Emarginate: When tip is deeply notched as in bambinia.

Leaf margin

ü  Entire-smooth margin

ü   Ciliate-with fine hairs

ü  Crenate-with rounded teeth

ü  Dentate-have large pointed teeth like margin

ü  Denticulate-with fine dentition

ü  Doubly toothed- serrate with sub-teeth

ü   Lobate-indented, but not to midline

ü  Serrate-have saw like margin

ü  Serrulate- with fine serration

Surface of the leaf

ü  Farinose-covered with a meal-like powder or minute particles

ü  Glabrouse- free from hairs

ü  Verucose-

ü  viscid- covered with sticky or resinous secretion

ü  punctate -dotted with oil glands

ü  pubescent-with hairs

ü  hirsute- with long distinct hairs

ü  hispid - with rough hairs

ü   glandular-