Green and Black Tea production

• Tea is derived from the prepared leaves and leaf bud of Thea sinensis L. (Camellia thea Link.) in the family Theaceae
• The part of the tea plant used is the two adjacent young leaves together with the stem and bud
• Tea's geographical origin includes India, Serilanka, China, and Japan
• Types of tea are categorized according to the drying process

Green Tea

• Green tea undergoes rapid drying
• High temperature is used in the preparation of green tea
• Green tea preparation involves stopping/destroying the oxidase enzyme
• No fermentation occurs during the preparation of green tea
• No oxidation of tannins occurs in green tea
• There is no change in chlorophyll color during the preparation of green tea

Black Tea

• Black tea undergoes slow drying
• Black tea preparation uses low temperature
• Complete oxidation by the oxidase enzyme occurs during the preparation of black tea
• Complete fermentation occurs during the preparation of black tea
• Oxidation of tannins takes place during the preparation of black tea
• Chlorophyll changes to a dark color during black tea preparation

Active Constituents in Both Types of Tea

• Green tea can be used with lemon (antiseptic) for diarrhea and has no effect on chlorophyll
• Soluble caffeine-phlobatannins complex exists in green tea
• No fermentation occurs due to the destruction of the oxidase enzyme by high temperature in green tea
• Tannins in green tea are in complex form with caffeine and are soluble
• Green tea contains less free caffeine, and higher amounts of tannins
• Black tea contains soluble caffeine-phlobatannins
• Insoluble phlobaphenes (tannins) + free caffeine exist in black tea
• Black tea's complete hydrolysis of complex occurs due to fermentation by the oxidase enzyme
• Tannins in black tea are in the form of phlobaphenes after hydrolysis and are insoluble
• Black tea has more caffeine due to complete hydrolysis of the complex and less tanning
• Traces of theobromine and theophylline alkaloids are active constituents in both types of tea
• Volatile oil is an active constituent in both types of tea
• Saponin glycosides are active constituents in both types of tea
• Flavonoids glycosides are active constituents in both types of tea
• Green tea is used as an antioxidant and antitumor agent because it contains more flavonoids

Confirmatory Chemical Tests

• These tests are used to confirm the presence of active constituents
• Includes the name of the test, the active constituent being tested for, procedure/reagents used, and the result

Murexide Test

• Used to test for caffeine
• Aqueous decoction is evaporated, and the residue is treated with concentrated HCl + H₂O
• Further evaporation to dryness occurs, resulting in the formation of a yellow color that turns crimson red residue
• Adding vapors of ammonia results in a violet color

Ferric Chloride Test

• Used to test for tannins
• An aqueous extract is treated with FeCl3, resulting in a green color

KOH Test

• Used to test for flavonoids glycosides
• An acidic extract is treated with KOH, resulting in a yellow color

Froth Test

• Used to 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
• Due to the presence of caffeine, tea acts as a CNS stimulant, diuretic, and weak smooth muscle relaxant
• Due to the presence of tannins, tea is used as an antidiarrheal drug and is a constipating agent
• Green tea is an antioxidant and anticancer agent

Precautions of Taking Large Doses of Tea

• Inflammation in the stomach can occur
• Gastritis, nervous irritability, anemia, or constipation can occur
• Taking large doses of tea can cause a habituation syndrome and an increase in heart rate

Digitalis (Foxglove)

• Origin: dried leaves of Digitalis purpurea and Digitalis lanata, family Scrophulariaceae

Active Constituents of Digitalis

• Cardiac glycosides including Digoxin, Digitoxin, Lanatoside A, and Lanatoside C
• Saponin glycosides

Confirmatory Chemical Tests for Digitalis

• These tests determine the active constituents; description includes the name of the test, active constituent – Procedure/reagents Used – and the Result.

Baljet Test

• Used for cardiac glycosides
• Alcoholic extract with Baljet reagent (Picric acid + 10% NaOH = Sodium picrate) shows an orange to yellow color compared with a blank control

Keller–Killiani Test

• Used for deoxy sugar in glycone part
• Acetic acid extract gives with FeCl3 + Conc H₂SO₄ creates a reddish-brown ring at the junction of the two layers and the upper layer turns bluish-green

Froth Test

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

Medicinal Uses of Digitalis

• Correlate each use with the active constituent
• Digitalis has a cardiotonic action on a diseased heart
• Digitalis strengthens the heartbeat, increase the force of contraction of the heartbeat and enables the heart to beat more strongly, slowly, and regularly without requiring more oxygen

Precautions of Digitalis

• Cardiac glycosides in digitalis are excreted very slowly, leading to a cumulative effect which may be fatal
• This makes digitalis suitable only as long-term medication.

Morphology of Digitalis

• The petiole of digitalis is petiolate
• Lamina (leaf blade) characteristics:
  • Apex is acute
  • Shape is lanceolate and decurrent
  • Margin is entire but ciliated at the base
  • Form (Type) is simple
  • Venation is reticulate anastomosing near the margin
  • Apex is exstipulate symmetric, decurrent where the base continues downwards as wings along the petiole
• Phyllotaxis is alternate

Key Elements of Digitalis

• The KOH mount of the powdered plant shows:
  • Fragments of epidermal cells with beaded anticlinal walls and anomocytic stomata with striated cuticle (Characteristic of Digitalis)
  • Three types of glandular hairs: bicellular biserriate head with unicellular stalk
  • Unicellular head and unicellular stalk
  • Unicellular head and multicellular uniserriate stalk
• Two types of non-glandular hairs: Collapsed hair (Characteristic of Digitalis) and Multicellular uniserriate
• Digitalis doesn't contain any type of calcium oxalate

Histology of Leaves

• Structures from top to bottom are: Cuticle, Upper epidermis, Palisade mesophyll cell, Bundle sheath cell, Xylem, Phloem, Lower epidermis, Spongy mesophyll cells, Guard cell, Stoma, Cuticle
• The ordinary leaf consists of: Upper and lower epidermis - The lower surface is usually covered with more stomata which are responsible for the gaseous exchange, Mesophyll - which lies in between the two epidermis and Cortical tissues - which surround the vascular bundle that traverse the mesophyll

###Microscopic characteristics of leaves: - Form and number of stomata - Trichomes: including Secretory (glandular hairs) and covering trichomes (non-glandular hairs) - Presence of crystals such as calcium oxalate

Forms of Leaves

• Simple Leaves: Leaves have blades that are not divided into distinct morphologically separate leaflets, but form a singular shape, the leaf is not divided
• Lobed or deeply lobed form are in which lobes are arranged on the sides of a central axis, like a feather
• Compound: Each blade is divided into smaller leaflets to form either Pinnate - leaflets arise along sides of the rachis which is the extension of the petiole
• Parallel venation is a characteristic feature of monocotyledons

Senna (Alexandrian & Indian Senna)

• Senna is a compound
• Origin: The dried leaflets of Cassia acutifolia (Alexandrian Senna) and Cassia angustifolia (Indian Senna) Family Leguminosae

Active Constituents of Senna

• Anthraquinones glycosides and Sennoside A, B, C, D upon hydrolysis Sennidin A, B, C, D.
• Carbohydrates

Confirmatory Chemical Tests for Senna

• Borntrager's test: for free anthraquinones: chloroformic extract gives with NH4OH a rose (pink) to intense red in the aqueous layer

Medicinal Uses of Senna

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

Precautions for Senna

• Due to presence of anthraquinones glycosides, senna should not be taken for more than 10 days since it leads to weakening of the large bowel muscles
• Side effects include a slightly bitter taste and causing nausea and as being a cathartic, it causes gripping and colic so it is mixed with other aromatic, carminative herbs that relax the intestinal muscles examples: Mentha, anise, cardamom, clove, antispasmodic (belladonna)
• Contraindications include for when it should not be taken during pregnancy, since it causes muscle contraction which may lead to abortion, and woman breastfeeding
• Morphology includes a petiolate

###Senna Lamina (leaf blade)

• Shape is obovate, lanceolate
• Margin is entire
• Form (Type) is compound, pinnate, paripinnate (even number)
• Venation is reticulate (netted) and pinnately reticulate

###Senna Key Elements

• Phyllotaxis is alternate
• Palisade cells (leaf organ) in longitudinal cholenchyma