Tì Uaine is Dubh

• Tea is from Thea sinensis L. (Camellia thea Link.) of the family Theaceae
• Part used is the two adjacent young leaves together with stem and bud
• Geographical origin includes India, Serilanka, China, and Japan

Types of Tea

• Types of tea depend on the method of drying used: green tea and black tea

Green Tea

• Rapid drying process
• High temperature is used
• The oxidase enzyme is stopped or destroyed
• No fermentation occurs
• No oxidation of tannins takes place
• No change in chlorophyll color

Black Tea

• Slow drying process
• High temperature not used
• Complete oxidation by oxidase enzyme occurs
• Complete fermentation occurs
• Chlorophyll changes to dark color
• Oxidation of tannins takes place

Active Constituents (Both Types)

• Green tea has no effect on Diarrhea use lemon (antiseptic)
• Green tea has no effect on chlorophyll

Green Tea

• Soluble caffeine-phlobatannins complex
• No fermentation occurs due to the destruction of the oxidase enzyme by high temperature
• Tannins are in the form of a complex with caffeine and are soluble
• Has less caffeine and increased tannins

Black Tea

• Soluble caffeine-phlobatannins
• Insoluble phlobaphenes (tannins) + free caffeine.
• Complete hydrolysis of complex due to fermentation by oxidase enzyme
• Tannins are in the form of phlobaphenes after hydrolysis and are insoluble
• More caffeine due to complete hydrolysis of complex with less tanning
• Contains traces of theobromine & theophylline alkaloids, volatile oil, and saponin glycosides
• Flavonoid glycosides exist in Green tea in larger quantities making it an antioxidant and antitumor

Confirmatory Chemical Tests

• These tests are used to confirm the presence of certain active constituents

Murexide test

• Test for caffeine
• Aqueous decoction is evaporated; the residue is treated with concentrated HCl + H2O then evaporated till dryness
• Yellow color is formed, which turns crimson red
• When residue is exposed to vapors of ammonia, a violet color is formed

Ferric chloride test

• Test for tannins
• Aqueous extract gives a green color with FeCl3

KOH test

• Test for flavonoids glycosides
• Acidic extract gives a yellow color with KOH

Froth test

• Test for saponin glycosides
• Powdered drug is shaken with water to give persistent froth that remains for 5 minutes

Medicinal Uses

• Correlate each use with the active constituent
• Caffeine in tea acts as a CNS stimulant, diuretic, and weak smooth muscle relaxant
• Tannins make tea used as an antidiarrheal drug (constipating agent)
• Green tea is an antioxidant and anticancer

Precautions of Taking Large Doses of Tea

• Can cause gastritis (inflammation)
• Can cause nervous irritability
• Can cause anemia
• Can cause constipation
• Can cause a habituation syndrome
• Can increase heart rate

Digitalis (Foxglove)

• The dried leaves of Digitalis purpurea and Digitalis lanata in the family Scrophulariaceae
• Active constituents include Digoxin, Digitoxin, Lanatoside A, and Lanatoside C; also saponin glycosides

Baljet test

• Test for cardiac glycosides
• Alcoholic extract treated with Baljet reagent (Picric acid + 10% NaOH = Sodium picrate) gives an orange/yellow color compared with blank

Keller – Killiani test

• Test for deoxy sugar in glycone part
• Acetic acid extract with FeCl + Conc H2SO4 shows a reddish-brown ring at the junction of the two layers, and the upper layer turns bluish green

Froth test

• Test for saponin glycosides
• Powdered drug is shaken with water to give persistent froth that remains for 5 minutes

Medicinal uses

• Digitalis has a cardiotonic action on a diseased heart
• It strengthens the heartbeat
• Increases the force of contraction of the heartbeat
• Enables the heart to beat more strongly, slowly, and regularly without requiring more oxygen

Digitalis precautions

• Cardiac glycosides are excreted slowly with a cumulative effect (may be fatal)
• Preferred for long-term medication

Digitalis Morphology

• Petiole is petiolate
• Lamina (leaf blade) has an acute apex, lanceolate and decurrent shape, an entire but ciliated margin at the base, and is simple in form
• Venation is reticulate anastomosing near the margin
• Apex is exstipulate symmetric and decurrent, where the base continues downwards as wings along the petiole
• Phyllotaxis is alternate

Digitalis Key Elements

• Fragments of epidermal cells with beaded anticlinal walls and anomocytic stomata with striated cuticle (characteristic)
• Three types of glandular hairs including bicellular biserriate head unicellular stalk, unicellular head unicellular stalk (capitate hair), and unicellular head multicellular uniseriate stalk
• Two types of non-glandular hairs including collapsed hair (characteristic) and multicellular uniserriate
• Does not contain calcium oxalate

Leaf Histology

• The ordinary leaf consists of upper and lower epidermis, mesophyll, cortical tissues and a vascular system
• Upper and lower epidermis: The lower surface of the leaf is covered with more stomata for gaseous exchange
• Mesophyll lies in between the two epidermis layers
• Cortical tissues surround the vascular bundle
• Stomata are responsible for the gaseous exchange
• Cortical tissues which surround the vascular bundle that traverse the mesophyll provides protection

Microscopic characteristics of leaves include:

• Form and number of stomata
• Trichomes: including secretory (glandular hairs) and covering trichomes (non-glandular hairs)
• Presence of crystals such as calcium oxalate

Leaf Venation

• Netted venation is a feature of dicotyledons

Types

• Pinnately netted: Veins branch off or radiate from a central mid vein.
• Palmately netted: Several major veins radiate out from a point.

Leaf Arrangement on Stem

• Alternate: Leaves occur in an alternate arrangement (1 leaf per node)
• Opposite: Nodes are opposite each other on the stem (2 leaves per node)
• Opposite Decussate: Special case of opposite, where each successive pair of leaves is at a right angle to the previous pair (typical for the mint family, e.g., Labiatea)
• Whorled: Three or more leaves arise from one node

Forms of Leaves

• Simple: Leaves have blades that are not divided into distinct morphologically separate leaflets, but form a single blade
• Entire (single) blade: the leaf is not divided
• Lobed or deeply lobed
• Pinnately lobed: Lobes arranged on the sides of a central axis
• Palmately lobed: Lobes spread radially from a point
• Compound: Each blade is divided into smaller leaflets to form either a pinnate or palmate arrangement
• Pinnate: Leaflets arise along sides of the rachis (extension of petiole)
• Paripinnate: Leaflets are in even number
• Imparipinnate: Leaflets are in odd number
• Palmate: Leaf is divided into 5 or more leaflets radiating from the top of the petiole

Types of Venation

• Parallel venation is a characteristic of monocotyledons
• Veins run approximately parallel to each other

Types of Parallel Venation

• Multicostate: Multiple main veins or ribs radiate from the base of the leaf
• Unicostate: A single main vein runs through the center of the leaf blade

Morphological structure of a Dicot Leaf

• Leaves display distinct variations in shape and form
• Leaves consists of a broad, flat lamina/blade and stalk, and some leaves possess small/leaf like outgrowth from the base called stipules
• Petiole (optional): Attaches blade to stem
• Lamina/Blade: Broad and flat, collects light for photosynthesis
• Veins: Contain vascular tissue
• Axil: Point of attachment of the leaf at the node of the stem
• Stipules (optional): Outgrowths at the base of the leaf

Different Kinds of Leaves

• Cotyledons (seed leaves): Leaves of the embryo, for food storage
• Foliage leaves: Ordinary green leaves, used in photosynthesis
• Floral leaves: The reproductive parts of the flower which include sepals, petals, stamens, and carpels
• Bract leaves: Leaves having a flower in their axils, whose axillary bud becomes a flower
• Scale leaves: Occur on subterranean stems (thin, membranous, and without chlorophyll), to protect the inner parts
• Modified leaves: When the leaf is modified into special structure for the purpose of carrying out special function
• Some leaves are modified to Spines against animals, and Tendrils for climbing as in case of grapes

Senna (Alexandrian & Indian Senna)

• Dried leaflets of Cassia acutifolia (Alexandrian Senna) and Cassia angustifolia (Indian Senna) from the family Leguminosae
• Active constituents include anthraquinones glycosides (Sennoside A, B, C, D) and mucilage (carbohydrates)

Senna Confirmatory Chemical Tests

Borntrager's test

• For free anthraquinones
• Chloroformic extract mixed with NH4OH results in a rose (pink) to intense red color in the aqueous layer

Modified borntrager's

• For combined anthraquinones
• Chloroformic extract mixed with NH4OH results in a rose (pink) to intense red in the aqueous layer

Senna Medicinal Uses

• Due to presence of anthraquinones glycosides, senna is used as a laxative and powerful cathartic in the treatment of constipation

Senna Precautions

• Senna should not be taken for more than 10 days because it leads to weakening of the large bowel muscles

Senna Side Effects

• Due to the presence of anthraquinones glycosides, senna has a slightly bitter taste and causes nausea
• Senna is also cathartic (very strong laxative) and causes gripping and colic
• Mixed with aromatic carminative herbs that relax the intestinal muscles such as mentha, anise, cardamom, clove, or antispasmodics like belladonna, to reduce colic effects

Senna Contraindications

• Should not be taken during pregnancy because it causes muscle contraction which may lead to abortion
• Contraindicated during woman breastfeeding

Senna Morphology

• Petiole is petiolate
• Lamina (leaf blade) Shape is obovate or lanceolate. Margin is entire
• Compound, pinnate, paripinnate (even number) form
• Venation is reticulate (netted) and pinnately reticulate
• Phyllotaxis is alternate

Senna Key Elements

• Palisade cells (leaf organ)