Triterpenes and Tea Leaves: Medicinal Properties and Uses

Triterpenes

• Eucalyptone and Macrocarpals have antibacterial and anti-HIV properties

Tea Leaves

Origin

• Green Tea Leaves: Leaves of Thea sinensis (Theaceae) subjected to heat treatment to inactivate oxidase enzymes and dried
• Black Tea Leaves: Same origin, but leaves are allowed to ferment, resulting in polyphenols converted to condensed tannins before drying in a hot air oven
• Native to China

Macroscopic

• Green Tea: More or less curled leaf fragments
• Black Tea: Much shriveled leaf fragments; shape can be examined better after boiling or steeping
• Higher quality tea consists of buds or young leaves with serrated margin

Microscopic

• Irregularly branched sclereid idioblasts in the mesophyll are characteristic elements

Active Constituents

• Green Tea: Polyphenols (Catechins and Epigallocatechin3-O-gallate (EGCG)), Flavonoids (type Flavonols), Traces of Volatile Oil (around 75 components)
• Black Tea: Oligomeric oxidation products of catechins (brown color) and condensed tannins, Flavonoids (around 300 components), Traces of Volatile Oil

Actions

• Xanthine alkaloids: Caffeine (CNS stimulant), Theophylline (smooth muscle relaxant), Theobromine (diuretic)
• Catechins and Epigallocatechin3-O-gallate (EGCG): Potent antioxidant

Indications

• Green and Black Tea: CNS stimulant drinks for mental and physical fatigue
• Green Tea: Useful for chemoprevention, supportive in diet control
• Isolated alkaloids are used as conventional drugs:
  • Caffeine: CNS stimulant antidote for CNS depressants
  • Theophylline: In asthma (individualized doses, low therapeutic index)

Ginkgo Leaves

Origin

• Leaves of Ginkgo biloba (Ginkgoaceae)
• Native to China and Japan

Macroscopic

• Dark to yellowish green, fan-shaped whole or fragmented leaves, no leaf midrib

Microscopic

• Very elongated tannins idioblasts, Clusters of Ca2+ oxalate

Constituents

• Flavonoids, Lactones (Ginkgolides and Bilobalide)

Indications and uses

• Geriatric cerebral insufficiency problems
• Cause some improvement in Alzheimer disease (adjunct therapy)
• Intermittent Claudication (Improving pain-free walking distance)

Side effects

• Mild G.I. disturbances
• Headache
• Allergic skin reactions

Senna Leaves

Origin

• Leaves of Cassia acutifolia (Alexandrian) or Cassia angustifolia (Indian) (Leguminosae)
• Native to Egypt

Macroscopic

• Ovate-lanceolate with short petiole and asymmetric base

Microscopic

• Paracytic stomata
• Unicellular warty cuticle trichomes
• Crystal sheath with Calcium oxalate prisms

Constituents

• Glycosides (Sennosides A, B, C, and D)
• Other components in senna extract provide 30% more synergistic effect than pure sennosides

Indications and uses

• Most frequently used laxative (Acute constipation, prior to bowel surgery, Hemorrhoids)

Mechanism of Action

• Sennosides inhibit Na+/K+ ATP-ase in colon mucosa, enhancing contraction and emptying

Drug Interactions

• K+ depletion with prolonged use potentiates action and toxicity of cardiac glycosides and anti-arrhythmic agents
• K+ depletion can be potentiated by diuretics and corticosteroids

Side effects

• Urine Red discoloration
• Sennosides may pass to fetus in pregnancy and to breast milk, which may lead to teratogenicity

Contraindications

• Pregnancy and Lactation
• Children under 10 years
• Chronic constipation
• Severe dehydration
• Overdose causes colic and thin liquid stools (over emptying of bowel) and prolonged use causes water loss (dehydration) and hypokalemia

Eucalyptus Leaves

Origin

• Leaves and branches of Eucalyptus globulus (Myrtaceae)
• Native to Australia

Macroscopic

• Coriaceous thick leaves with grayish dark brown warts, translucent oil glands are seen

Microscopic

• Large oil glands (E)
• Corky warts of 10 or more cell layers (K)
• Small polygonal epidermal cells with straight walls
• Clusters and prisms of Ca2+ oxalate

Constituents

• Flavonoids
• Volatile oil, mainly cineole