Flower Drugs: Clove and Pyrethrum PDF

Flower Drugs: Clove and Pyrethrum U. I. Olayemi (M. Sc. ; B.Pharm. Ife) Department of Pharmacognosy, Faculty of Pharmacy, O. A. U. Ile-Ife. 1  Clove: Botanical Defintion Cloves are the dried flower buds of Syzygium aromaticum (syn. Eugenia...

Flower Drugs: Clove and Pyrethrum U. I. Olayemi (M. Sc. ; B.Pharm. Ife) Department of Pharmacognosy, Faculty of Pharmacy, O. A. U. Ile-Ife. 1  Clove: Botanical Defintion Cloves are the dried flower buds of Syzygium aromaticum (syn. Eugenia caryophyllus) (L.) Merr. & Perr. (Myrtaceae). It is a tree of 10-20 m high It is indigenous to the clove islands It is cultivated in Zanzibar, Madagascar, Brazil 2  Clove: Cultivation and preparation The clove flower buds are collected between August and December when the lower parts turns from green to crimson If left too long on the tree, the buds open, the petals fall off leaving ‘blown cloves’ and then fruits known as ‘mother cloves’ are produced. The clove flower buds are dried in open air and separated from their peduncles which are known as ‘clove stalks’. 3  Clove: Macroscopy Cloves are 10-17.5 mm long, colour - blackish to reddish brown It consists of a ‘head’ on a cylindrical hypanthium. The head consists of 1. Four calyx teeth (sepals) 2. Four imbricated petals 3. Numerous incurved stamens around a large style The ovary within the hypanthium is bilocular with numerous ovules attached to the axile placentae 4  Clove: Macroscopy continued Odour- strong, fragrant, spicy Taste- pungent, aromatic Sink in water Exude oil when pressed between the fingers Exhausted cloves don’t exude oil Varieties of clove include 1. Penang & Amboyna varieties (larger and plumpest, reddish-brown in colour) 2. Zanzibar variety- smaller and leaner, blackish brown in colour) 5 Clove: Microscopy (Transverse section) The hypanthium below the ovary shows an epidermal layer with stomata radially arranged parenchymatous cells with 1. oil glands 2. calcium oxalate crystals a ring of vascular bundles lignified fibres a zone of aerenchyma composed of air spaces which supports the central columella The collumella is parenchymatous, rich in calcium oxalate, with an outer region of 17 small vascular bundles 6 Clove: Microscopy (Transverse section) continued The hypanthium in the region of the ovary shows an outer epidermis an oil gland layer a ring of bicollateral bundles strongly thickened cellulose walls an inner epidermis (which forms the wall of the ovary) the dissepiment of the ovary is parenchymatous the placentae is rich in cluster crystals of calcium oxalate and vascular bundles 7  Clove: Microscopy continued The sepals and petals have a simplified leaf structure with the mesophyll parenchyma containing calcium oxalate and oil glands The epidermis of the sepals contain stomata while the petals are devoid of stomata and are composed of irregular cells The stamens are composed of filament, connective and anther The filament has epidermal cells, parenchyma cells embedding numerous oil glands The anther wall has cells with lignified thickening and triangularly shaped pollen grains 15- 20 um in diameter 8  Clove: Chemical constituents 1. About 14-21 % of volatile oil which is colourless or pale yellow slightly heavier than water turns darker in colour with treatment with alcoholic FeCl3 Gives crystals of potassium eugenate with treatment with alcoholic KOH due to the presence of eugenol 2. Tannins (10-13 %) 3. Acids 4. esters 5. glycosides 9  Clove: Uses 1. Stimulant aromatic 2. Flavouring agent 3. Spice 4. Antiseptic (Volatile oil) 10  Further reading and assignment Study the macroscopical and microscopical diagrams in Trease and Evans. Pharmacognosy. 15th Edition. Pages 274-276 11  Pyrethrum: Botanical definition Pyrethrum flowers are the dried flower heads of Chrysanthemum cinerariifolium (Trev.) Vis. (Asteraceae). Synonyms are 1. Tanacetum cinerariifolium (Trev.) Sch. Bip 2. Pyrethrum cinerariifolium Trev. Common name- Insect flower The plant is perennial, about 1m high and Kenya is the largest exporter due to favourable conditions of cultivation present 12 Pyrethrum: Cultivation & Preparation 13  Pyrethrum: Macroscopy The pyrethrum flower head is composed of florets set on a slightly convex receptacle. The disk florets, representing the yellow flower heart, densely populate the centre of the receptacle and are surrounded by an outer ring of white ray florets. Each disk floret has a yellow tubular corolla with a small calyx at its base. The inner surface of the tubular corolla has five stamen filaments, rising from the base which terminate in elongated anthers. The anthers join together to form a cylinder, at the centre of which rises the style from the ovary that opens in the form of two lobes ready for pollination. The ray florets are 10-20 mm in length and have about 17 veins and 3 rounded teeth, the central one very small. Closed flower head is 6-9 mm in diameter Open flower head is 9-12 mm in diameter The involucre consists of yellowish, lanceolate hairy bracts. Peduncle is short with longitudinal striations 14  Surface view of two pyrethrum flower heads A: Longitudinal section of a disk floret; B: Longitudinal section of flower head 15  Pyrethrum: microscopy The species used as insecticides are C. cinerariifolium, C. coccineum and C. marshallii The microscopy of the powder shows 1. Parenchyma often containing aggregate crystals 2. T-shaped hairs 3. Numerous spherical pollen grains 4. Sclerenchyma cells 5. Tracheids 6. Epidermal cells having striated papillose cuticle 16  Pyrethrum: Chemical constituents Six esters are responsible for the insecticidal properties of pyrethrum. 1. Pyrethrin I (largely responsible for lethality) 2. Jasmolin I 3. Cinerin I 4. Pyrethrin II (largely responsible for rapid knock-down action) 5. Jasmolin II 6. Cinerin II 17 Pyrethrum: Chemical constituents 18  Pyrethrum: Chemical constituents Pyrethrum extract B.P. (Vet.) contains 24.5- 25.5 % of pyrethrins Synthetic analogues of the natural pyrethrins are more popular as domestic sprays due to 1. higher insecticidal activity (over 1000x that of pyrethrin I) 2. greater photostability 3. similar low mammalian toxicity 19  Pyrethrum: uses Pyrethrum powders and sprays are used as a contact poison for insects in special areas like food processing plants and insecticidal spraying of edible fruits and vegetables shortly before harvest. 20