S1 L4 Evaluation of plant drugs

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S1 L4 Evaluation of plant drugs

• 1. Botanical
• B. Microscopy
• Cell inclusions
• Anna Drew

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Cell inclusions

• Parenchyma cells
• Contain characteristic contents of living
  protoplasts
• Eg nucleus, cytoplasm, vacuoles, plastids,
  mitochondria
• Not diagnostically useful
• Non-protoplasmic components
• Classified as ergastic substances
• Starch
• Protein
• Oil
• Crystals
• Very useful for identification

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• 1. CALCIUM OXALATE
• Crystals may be reserve or waste products of
  cellular activity
• Oxalate ions removed in making crystals
• Dont know why they arise (could be pH)
• Or why they are found in particular locations
  (vascular tissue) and not others (near veins)
• Clearing agents
• Chloral hydrate solution to remove chlorophyll
  (cell walls etc remain)
• Show in crossed polaroids
• Comment on size, shape, frequency

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(a) Prisms

• One prism per parenchyma cell
• Cells form a sheath around fibres in vascular
  bundle
• Eg cascara, senna, liquorice

Hyoscyamus leaf
Twin crystals
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Calcium oxalate of Cassia acutifolia (senna)
leaflet (viewed under high power)
Note cluster crystals also present in senna
leaflet
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(b) Clusters rosettes

• Microrosettes in Umbelliferae eg anise, fennel

Eg Senna Cascara Stramonium
Eg Rhubarb rhizome
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Calcium oxalate of Datura Stramonium leaf (viewed
under high power)
Calcium oxalate of Datura stramonium leaf (viewed
under low power)
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(c) Needles (acicular)

• Occupy the whole parenchyma cell
• Next cell contains none
• Eg ipecacuahna, squill

Calcium oxalate of Cephaelis ipecacuanha rhizome
(viewed under high power)
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(d) Microsphenoids (crystal sand)

• Very small
• Adjacent cells dont store them
• Eg belladonna

Calcium oxalate of Atropa belladonna leaf (viewed
under high power)
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• 2. CALCIUM CARBONATE
• Not as common as calcium oxalate
• Eg cannabis cell

Calcium carbonate deposit
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Maltese cross effect (page 15 microscopy notes)

• 3. STARCH GRAINS
• More common
• Occur as discrete grains
• Commonly show layering of amylose amylopectin
  around a point hilum
• Found in parenchyma of pith, cortex, vascular
  tissues, fruits, cotyledons seed endosperms
• Generally not found in leaves transported out
• Staining
• Dilute glycerin
• Chloral hydrate to dissolve pigments
• I2 blue-black stain
• Polarised light not bright

Characteristics of plant starch
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• Shape
• One shape will be dominant or characteristic of a
  plant Eg
• Polyhedral maize starch
• Ovoid with a few round potato
• Sac shape ginger
• Aggregation
• Can be single, 2, 3 -gt multicompound grain
• Eg ipecacuanha
• Size
• Rice 6 µm
• Potato 45-70 µm

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• Hilum
• Striations
• Present or absent
• Layers of amylose and amylopectin
• Frequency
• Absent rare abundant (90 of plant material)
• Location
• Where they are found Eg root, rhizomes, seeds etc
• May just be in specific tissues Eg pith, cortex,
  perisperm

Single point
Line in a grain
Punctate (hole)
Cleft
Stellate
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Potato starch grains (viewed under high power)
Maize starch grains (viewed under high power)
Cephaelis ipecacuanha rhizome starch
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• 4. PROTEIN
• Indicative of seed material
• Diagnostic feature
• Picric acid stains protein yellow
• Allow a few minutes to stain, wash away rest

Aleurone Eg Linseed
Amorphous
Globoid
Amorphous protein
Calcium oxalate
Crystalloid protein
Phosphorus protein
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• 5. OILS, FATS
• May float out in stain to below coverslip
• Fixed oil
• Esters of glycerol
• Eg linseed, olive
• Volatile (essential) oil
• Look the same
• Turpine and hydrocarbons
• Eg peppermint
• Can smell
• Staining
• Sudan III, Tincture of Alkanne
• Some plants contain so much oil that it needs to
  be removed to see other structures
• Light petroleum removes fat
• Mix, decant off, repeat several times, then can
  stain

Globules
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• 6. MUCILAGE
• Sometimes present
• Has to be stained to be seen
• Staining
• Ruthenium red -gt pink
• Eg senna leaves