شاي الكاميليا واستخداماتها

Medicinal Plants - Leaves Containing Alkaloids

• Lecture 11: Focuses on leaves containing alkaloids. Different types of leaves are discussed, including their origins, morphology, active constituents, chemical tests, and actions/uses.

Jaborandi Leaves

• Origin: Dried leaflets of Pilocarpus microphyllus and P. jaborandi, family Rutaceae. Grown in Brazil.
• Morphology: Compound leaves, specifically imparipinnate leaflets with notched apexes.
• Active Constituents: Alkaloids (pilocarpine, isopilocarpine, pilosine, isopilosine) and volatile oils.
• Chemical Test (for pilocarpine): Helch's test using powder, sulfuric acid, and a filtration step, creating a perceptible colour change.
• Action and Uses: Parasympathomimetic action, impacting the eye (miotic, reducing pupil size) and increasing secretions like sweat and saliva. Used as an antidote for atropine poisoning and in ophthalmology (as a miotic). Useful in glaucoma treatment because it decreases intraocular pressure; also a sialagogue (increasing saliva) and diaphoretic (increasing sweating).

Boldo Leaves

• Origin: Dried leaves of Peumus boldus, family Monimiaceae. Grown in Chile.
• Morphology (Microscopically): Distinguished by the presence of stellate hairs.
• Active Constituents: Alkaloids (boldine), glycosides (boldoglycin), and volatile oils (in oil cells).
• Chemical Tests (for Boldine): Alcoholic extracts with vanillin HCl solution produces an intense red colour.
• Action and Uses: Hepatic stimulant or tonic (used in jaundice), mild diuretic, and mild laxative.

Tea Leaves

• Origin: Prepared leaves and leaf buds of Camellia sinensis (also known as Thea sinensis), family Theaceae. Grown in Eastern Asia (Ceylon, China, Japan, India, Kenya).
• Processing Methods: Different processing methods lead to different tea types (white, green, black, oolong). Drying methods are key: fresh leaves are dried after wilting and sometimes steaming.
• Types of Tea: Black tea is made through full oxidation, while green tea is made through steaming, avoiding oxidation. White tea involves minimal processing.
• Active Constituents: Alkaloids (caffeine, theobromine, theophylline), tannins (10-24%), flavonoids, volatile oils, and saponins.
• Action and Uses: CNS stimulant (due to caffeine), astringent and antidiarrheal (due to tannins), mild diuretic (due to theobromine), weak smooth muscle relaxant (due to theophylline). Green tea is an antioxidant and anticancer, thanks to polyphenols. Large doses lead to constipation, stomach irritation, gastritis, and nervous irritability.

Coca Leaves

• Origin: Dried leaves of Erythroxylum coca (Bolivian coca) or E. truxillense (Peruvian coca), family Erythroxylaceae. Grown in Bolivia and Peru.
• Physical Characteristics: Tea-like odor; bitter taste followed by numbness.
• Active Constituents: Alkaloids (cocaine, cinnamylcocaine, α- and β-truxillenes), and tannins (cocotannic acid).
• Action and Uses: Central nervous system (CNS) stimulant (a small dose). A large dose may even lead to a nervous system depressant effect and, potentially, cardiac arrest. Subcutaneous injection of cocaine causes paralysis of sensory nerves. Used as a local anesthetic (cocaine HCI) in minor surgeries of the ear, nose, and eye. Important note that cocaine use is highly restricted due to its toxicity and addictive nature.