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

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

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

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

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

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 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

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 45-70 µm

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

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 Crystalloid protein Phosphorus 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 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

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