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Transcript
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 » » » » 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: » » » » 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