1. S1 L4 Evaluation of plant drugs
1. Botanical
B. Microscopy
Cell inclusions
Anna Drew

2. Cell inclusions Parenchyma cells Non-protoplasmic components
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

3. 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

4. (a) Prisms One prism per parenchyma cell
Cells form a sheath around fibres in vascular bundle
Eg cascara, senna, liquorice
Hyoscyamus leaf
Twin crystals

5. Calcium oxalate of Cassia acutifolia (senna) leaflet (viewed under high power)
Note – cluster crystals also present in senna leaflet

6. (b) Clusters & rosettes
Microrosettes in Umbelliferae eg anise, fennel
Eg Senna Cascara Stramonium
Eg Rhubarb rhizome

7. Calcium oxalate of Datura Stramonium leaf (viewed under high power)
Calcium oxalate of Datura stramonium leaf (viewed under low power)

8. (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)

9. (d) Microsphenoids (crystal sand)
Very small
Adjacent cells don’t store them
Eg belladonna
Calcium oxalate of Atropa belladonna leaf (viewed under high power)

10. 2. CALCIUM CARBONATE Not as common as calcium oxalate Eg cannabis cell
Calcium carbonate deposit

11. 3. STARCH GRAINS More common Occur as discrete grains
‘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

12. Aggregation Size 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 µm

13. Hilum Striations Frequency Location 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

14. Potato starch grains (viewed under high power)
Maize starch grains (viewed under high power)
Cephaelis ipecacuanha rhizome starch

15. 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

16. 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

17. 6. MUCILAGE Sometimes present Has to be stained to be seen Staining:
Ruthenium red -> pink
Eg senna leaves