Download L4 Evaluation of plant drugs

S1 L4 Evaluation of plant drugs
1. Botanical
B. Microscopy
Cell inclusions
Anna Drew
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
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Starch
Protein
Oil
Crystals
• Very useful for identification
1. CALCIUM OXALATE
• Crystals may be reserve or waste products of
cellular activity
• Oxalate ions removed in making crystals
• Don’t 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
(a) Prisms
Hyoscyamus leaf
Twin crystals
• One prism per parenchyma cell
• Cells form a sheath around fibres in vascular bundle
• Eg cascara, senna, liquorice
Calcium oxalate of
Cassia acutifolia
(senna) leaflet
(viewed under high
power)
Note – cluster
crystals also present
in senna leaflet
(b) Clusters & rosettes
Eg Senna
Cascara
Stramonium
Eg Rhubarb
rhizome
• Microrosettes in Umbelliferae eg anise, fennel
Calcium oxalate
of Datura
Stramonium leaf
(viewed under
high power)
Calcium oxalate
of Datura
stramonium leaf
(viewed under
low power)
(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)
(d) Microsphenoids (crystal sand)
• Very small
• Adjacent cells don’t store them
• Eg belladonna
Calcium oxalate of Atropa belladonna
leaf (viewed under high power)
2. CALCIUM CARBONATE
• Not as common as calcium oxalate
• Eg cannabis cell
Calcium carbonate
deposit
3. STARCH GRAINS
‘Maltese cross’
effect (page 15
microscopy
notes)
• 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:
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Dilute glycerin
Chloral hydrate to dissolve pigments
* I2 blue-black stain
* Polarised light – not bright
* Characteristics
of plant starch
• 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 -> multicompound grain
» Eg ipecacuanha
• Size
» Rice 6 µm
» Potato 45-70 µm
• Hilum
Single
point
Line in a
grain
Cleft
Stellate
Punctate
(hole)
• 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
Potato starch grains
(viewed under high power)
Maize starch grains
(viewed under high power)
Cephaelis ipecacuanha
rhizome starch
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
Phosphorus
protein
Crystalloid protein
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
Globules
• 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
6. MUCILAGE
• Sometimes present
• Has to be stained to be seen
• Staining:
– Ruthenium red -> pink
• Eg senna leaves