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S1 L3 Evaluation of plant drugs

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S1 L3 Evaluation of plant drugs 1. Botanical B. Microscopy Cell types Anna Drew Microscopy Powdered plant material identified Via observation of the types and form of ... – PowerPoint PPT presentation

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Title: S1 L3 Evaluation of plant drugs


1
S1 L3 Evaluation of plant drugs
  • 1. Botanical
  • B. Microscopy
  • Cell types
  • Anna Drew

2
Microscopy
  • Powdered plant material identified
  • Via observation of the types and form of
    individual diagnostic structures present
  • Presence of structures
  • -gt morphological group
  • Size, shape, frequency of characters
  • -gt exact species
  • Aided by identification tables
  • Essential to recognise the diagnostic structures!

3
Microscopy
  • Very good analytical technique
  • Quicker than extracting running a chromatogram
  • Quick way to check if it is a different plant or
    material contaminated
  • Magnification
  • M Me x Mo
  • eyepiece
    objective
  • Low power x 10 x 10
    x 100
  • High power x 10 x 40
    x 400

4
Adjuncts on microscope
  • (a) Polarized light
  • Polarized material in the eyepiece
  • With the analyser below it is arranged to get
    darkness
  • Crystalline material may rotate planes to show
    bright
  • Micromeasurement
  • Micrometer eyepiece scale (100 divisions)
  • Micrometer slide to calibrate the scale
  • Focus micrometer slide and align with eyepiece
    scale to calibrate it for low and high powers
  • Then replace with plant slide can measure
    objects in micrometres

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  • 1. PARENCHYMA (ground tissue)
  • Indicates plant tissue is present
  • Least specialized plant cells
  • Thin and somewhat flexible cell walls
  • Generally have a large central vacuole
  • Living at maturity
  • Found in all plant organs as a continuous tissue
  • cortex and pith of stems
  • ground tissue of petioles
  • mesophyll of leaves
  • endosperm of seeds
  • Also forms part of complex tissues such as
    vascular tissues
  • Most metabolic functions are carried out by
    parenchyma cells
  • Photosynthesis

11
  • Typical

Thin rounded cellulose walls
Air spaces
Isodiametric (rounded) cell
12
Modifications of parenchyma
  • Leaf tissue

Epidermal cell
Palisade mesophyll cell layer
Spongy mesophyll cells
13
  • Lignified
  • Indicates secondary thickening
  • Constituent of woody material

Pits in cell walls
Lignin in cell wall
14
  • Reticulate
  • Eg Fennel fruit (Foeniculum vulgare)

Large pit (surface view)
15
  • 2. COLLENCHYMA
  • Closely related to parenchyma
  • Thicker primary cells walls (usually with uneven
    thickness)
  • Living at maturity
  • Role in support of herbaceous plants
  • Example - the "strings" of celery
  • Occur in groups just beneath the epidermis
  • beneath cork in bark
  • at the midrib of leaf below and above vascular
    bundle

Cellulose thickening
16
  • 3. SCLERENCHYMA (support cells)
  • Thick secondary cell walls (showing simple
    pitting)
  • Dead at functional maturity
  • Cannot increase in length - occur in parts of the
    plant which have quit growing in length
  • Two types
  • FIBRES
  • long, slender cells with a more or less regular
    secondary cell wall
  • Usually occur in groups or strands
  • Commercial examples flax, jute, hemp (for
    making rope)
  • In dicots found in vascular tissue as xylem /
    phloem
  • In monocots they may enclose the vascular bundle
    or support it either side
  • Sometimes form columns from lower to upper
    epidermis
  • Fibre position, aggregation and general
    appearance makes then valuable diagnostic aids
  • Function support

17
  • Typical

Lignin
Pit (surface view)
Lumen
Pit (section view)
18
Cascara bark
  • Diagnostic features
  • Very narrow lumen
  • Found in groups
  • Very thick hard to see the lumen

19
Zingiber officinale (ginger) fibres viewed under
high power
20
Cinchona bark fibres (viewed under low power)
  • Diagnostic features
  • Found singly, not in a group
  • Very large
  • Funnel-shaped lumen
  • Striated wall
  • (Some ends blunted)

21
  • SCLEREIDS (stone cells)
  • Shorter or blunter cells with an irregular shape
  • Widely distributed in plants
  • Can vary considerably in shape
  • Typically
  • Isodiametric
  • Thick secondary walls
  • Numerous pits
  • May occur in layers or groups or alone
  • Found
  • in epidermal, ground or vascular tissue
  • In stems continuous sheath on the periphery of
    a vascular region
  • In leaves throughout or at ends of small veins
  • In fruits singly or in groups
  • Hardening of seed coats during ripening often
    results from layers of sclereids
  • Function
  • protection (seed coats)

22
  • Brachysclereid stone cells

Pits in surface
Thick wall
Lumen
Eg Pyrus communis - pear
23
  • Astrosclereid
  • TS Water lily
  • Lignified
  • Branched
  • Single cell

24
  • Osteosclereid
  • Cinnamon bark
  • Horseshoe shape
  • One wall much thinner
  • Irregular sclereid

Wild cherry bark Very irregular, sometimes
branched, (jigsaw piece)
Cascara bark Irregular, solid, many in groups
25
  • 4. VESSELS AND TRACHEIDS
  • Xylem
  • Thick secondary cell walls, often deposited
    unevenly in a coil-like pattern so that they may
    stretch
  • Dead at functionally maturity
  • Water/ion conduction vessels and tracheids
  • storage - parenchyma
  • support fibres and sclereids
  • Tracheid
  • More primitive
  • Pits allow water to pass from one to another
  • Less efficient at conducting water
  • More like a fibre
  • Vessel
  • End walls of linear parenchyma cells breakdown
    to form continuous tubes or channels
  • Only found in Angiosperms

26
Lignin arrangements
HERBACEOUS
WOODY PLANTS to conduct more water
Bordered pitted
Sclariform
Annular
Spiral
Reticulate
Eg Male fern rhizome
Eg Liquorice root
Eg Gentian root Rhubarb
27
Gentiana lutea (Gentian) root vessels (viewed
under high power)
Tracheids of Atropa belladonna root (viewed under
high power)
28
  • 5. PHLOEM
  • Not strong tissue collapses (as it grows)
  • Not good diagnostically
  • Involved in transport of sucrose, other organic
    compounds, and some ions
  • Living at functional maturity
  • Protoplast may lack organelles and nucleus,
    though
  • End walls connect to each other via sieve-plates
  • Two types of cells in the phloem
  • Sieve-tube members - actual conduit for sucrose
    transport
  • Companion cells - has a nucleus that may also
    control the sieve-tube element and may aid in
    sucrose loading

29
Holes in patches -sieve plate at an angle
Companion cell
Sieve area - conducts to next cell
Sieve plate
30
  • 6. LEAF EPIDERMIS
  • THE CUTICLE
  • Separate outer layer made of cutin, a fatty
    substance
  • Characteristic feature of epidermis
  • Sometimes striated diagnostic feature

Mint
Senna
Atropa belladonna
Digitalis
31
  • (b) EPIDERMAL CELLS
  • Continuous layer of cells covering surface of
    plant
  • Elongated parts of plant, stem or petiole, cells
    elongated
  • Leaves, petals, ovaries, ovules cells have wavy
    anticlinal walls and are roughly isodiametric
  • In some plants they have special features
  • Papillae
  • Cell inclusions (tannins, crystals)
  • (c) STOMATA
  • Openings in epidermal cell layer
  • Each stoma is bounded by two specialised guard
    cells
  • These control opening and closing of the pore by
    changing their shape

32
Anomocytic
Anisocytic
Paracytic
Diocytic
Senna
Mint
Digitalis
Belladonna
33
  • 7. TRICHOMES (Hairs)
  • Protective
  • Highly variable appendages
  • Glandular secretory
  • Non-glandular (covering) hairs, scales, papillae
    and absorbing hairs of roots
  • Can occur on any part of the plant
  • Persist throughout life of plant
  • When lost scar (or cicatrix) is left
  • Good diagnostic feature

34
Unicellular
Multicellular
Senna
Hyoscyamus Warty - Digitalis
Cannabis sativa
Anise
Stellate Witch hazel
Glandular
Hyoscyamus
Digitalis Belladonna
Belladonna
Unicellular stalk
Multicellular stalk
35
  • 8. PERIDERM (Cork)
  • Protective tissue
  • Replaces epidermis in stems and roots that have
    continuous secondary growth
  • Comprises
  • Cork tissue (phellem)
  • Cork cambium (phellogen)
  • Parenchyma (phelloderm)
  • Phellogen can arise in epidermis, cortex, phloem
  • Produces phellem to outside
  • Produces phelloderm to the inside
  • Cork particularly diagnostic
  • Characterised by suberisation suberin a fatty
    substance which covers (lignified) primary cell
    wall
  • Cork cells vary in thickness, colour

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  • 9. POLLEN
  • Produced in anthers
  • Varies considerably in size, shape, external
    characters
  • Can be useful diagnostically for drugs containing
    floral parts
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