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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
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  • Lignified
  • Indicates secondary thickening
  • Constituent of woody material

Pits in cell walls
Lignin in cell wall
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  • 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
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  • 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

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  • Typical

Lignin
Pit (surface view)
Lumen
Pit (section view)
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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)

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  • 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)

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  • Brachysclereid stone cells

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

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  • 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
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  • 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

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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
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Gentiana lutea (Gentian) root vessels (viewed
under high power)
Tracheids of Atropa belladonna root (viewed under
high power)
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  • 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
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  • 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
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  • (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

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Anomocytic
Anisocytic
Paracytic
Diocytic
Senna
Mint
Digitalis
Belladonna
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  • 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

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Unicellular
Multicellular
Senna
Hyoscyamus Warty - Digitalis
Cannabis sativa
Anise
Stellate Witch hazel
Glandular
Hyoscyamus
Digitalis Belladonna
Belladonna
Unicellular stalk
Multicellular stalk
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  • 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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