Tuesday, August 3, 2021

Pharmacognosy and Phytochemistry of Ephedra : An Amino Alkaloid / Proto-alkaloid

 Synonym

Ma-Huang (Ma-Astringent taste, Huang -Yellow)

Biological source
It consists of dried young stems of Ephedra gerardiana, E. nebrodensis (India), Ephedra sinica, Ephedra equisetina (China) Family: Gnetaceae / Ephedraceae.

Geographical source

China, Pakistan, North India, Australia, Kenya, Spain etc.

Morphological features



Fig.1: Ephedra Plant and its Stems


• This is an evergreen shrub which can grow up to 60 cm high.
• Ephedra has many different species.
• This plant is differentiated into 3 parts: root, stem and leaves.
• The plant is spread by the use of rhizomes.
• Stems are green, leaves are opposite in arrangement and whorled.
• The shape of leaves are scale like and have no resin canals.
• Seeds are yellow to dark brown in colour.
• The branches of this plant are slender, more or less broken aerial stems which are woody in nature and branched only at the base.


Macroscopic Characters of Ephedra gerardiana

·        Woody, cylindrical.

·        Colour: Grey to greenish

·        Taste: Bitter

·        Stems contain numerous, fine and longitudinal ridges.

  It has Nodes, internodes, scaly leaves and terminal buds.

·        Shows internodes at 3-4 cm distance.

·        The diameter of node is about 1-2 mm and diameter of internode is 3-6 cm.

Microscopy



Fig. 2: Schematic diagram of transverse section of ephedra stem


Fig. 3: Detailed histological diagram of transverse section of ephedra stem

 

·        Epidermis: Single layered, quadrangular cells, with thick and smooth cuticle. Vertical rows of sunken stomata present between many vertical ridges on the stem.

·        Cortex: Many layers of thin-walled cellulosic parenchyma. Below epidermis, two or three layers of loosely arranged palisade like cells are present. Cortex shows both lignified and unlignified fibers.

i) Unlignified fibers: like bunch of grapes occur below the ridges where no palisade cells are present.

ii) Fibres: Scattered, isolated or in groups of two to four cells lignified.

·        Pericyclic fibers: lignified, crown the phloem on its outer side

·        Vascular bundle: Around 10, collateral, conjoint, open and arranged in ring. Contains phloem and xylem

i) Phloem: It consists of sieve tubes and companion cells

ii) Xylem: It is made up of vessels, tracheid’s, parenchyma and fibro tracheids.

·        Pith: Large, thin walled, lignified parenchyma with intercellular space. Some cells contain dark brown mucilaginous substance (Brown matter).

 

Cultivation and Collection

  The plant favors light (sandy) and medium (loamy) soils and requires well-drained soil. The plant prefers acid, neutral and basic (alkaline) soils.

  It cannot grow in the shade. It requires dry or moist soil and can tolerate drought.

  Seeds are sown as soon as they are ripe in the autumn in a greenhouse.

  It can also be sown in spring in a greenhouse in sandy compost.

  Seedlings are transferred into individual pots as soon as they are large enough to handle and grown them for at least their first winter in a greenhouse.

  Drug is collected in autumn since it contains maximum percentage of alkaloids.

  Green slender twigs are collected in autumn, dried and packed loose in bags. Sometimes the twigs are pressed tightly.

Chemical constituents
 


  It contains Amino-alkaloids. Ephedra’s contain about 0.5 – 2.0 % of alkaloids.

  Chief Constituent: Ephedrine

  Norephedrine

  N-methyl ephedrine

  Pseudoephedrine

  Root Contains Macrocyclic alkaloid: Ephedradine

  Oxazolidone

  Tannins are also found in mostly ephedra species.

  Also contains flavonoids and polysaccharides.

Chemical test

Ephedrine + Water + dil.HCl + CuSO4 + NaOH. The solution gives blue colour. If shaken with solvent ether:  Organic Layer-Purple, Aq. Layer – Blue colour

 

Therapeutic Uses

  Ephedra shows sympathomimetic activity.

  In allergic conditions like hay fever, bronchitis, Woophing cough.

  To correct the low BP because of its peripheral contraction of arterioles.

  It has anti- inflammatory, anticancer, antibacterial, antioxidant properties.

  Pseudoephedrine is decongestant, cough suppressant and nor-pseudoephedrine is peripheral vasodilator used to treat angina.

  It is used as hepatoprotective, anti-obesity and antiviral.

  It also exhibits diuretic activity.

  Ephedra is used in the treatment of asthma (Bronchodilator) and hay fever.

  Ephedrine has more prolonged action than adrenalin as it is slowly hydrolyzed by MAO and also can be administered by mouth.

  It has anti-sudorific action.

 

Substituents and Allied Species

Ephedra sinica 

·        Thickness: 4–7 mm

·        Length: up to 30 cm of branches

·        Leaves: 2–4 mm long, opposite, decussate and subulate.

·        Leaf, base is reddish-brown, apex acute and recurved and lamina white in colour. 

Ephedra equisetina

·        Stems are woodier and more branched 

·        Length:  25–200 cm of branches and 1–2.5 cm of internodes,

·        Outer surface: Grey to pale green and smooth.

 Ephedra nebrodensis 

·        Stems are 15–35 cm long; 1–2 mm thick,

·        Cylindrical,

·        Colour: greenish-yellow

·        Nodes are brownish and distinct and fractured surface is fibrous in the cortex but pith contains brownish powdery mass.

·        Leaves: Brownish to whitish-brown in colour, scaly, connate, opposite and decussate, acute, agreeable and slightly aromatic odour and taste is astringent and bitter.

 

MULTIPLE CHOICE QUESTIONS (Answers are marked bold)

1. Ephedra gerardiana belongs to which one of the family…………..

(a) Apocyanaceae

(b) Leguminoceae

(c) Liliaceae

(d) Gnetaceae

 

2. The principal constituent of ephedra is ……

(a) Oxazolidon

(b) Pseudoephedrine

(c) Ephedradine

(d) Ephedrine

 

3. Characteristics of ephedra leaves include………..

(a) Scale like

(b) Opposite in arrangement

(c) Whorled

(d) All of the above

 

4. The important features of ephedra stem includes………

(a) Contain longitudinal ridges

(b) Woody

(c) Branched only at once

(d) All of the above

 

5. Ephedra contains ………..

(a) Amino alkaloids

(b) Tropane alkaloids

(c) Indole alkapoids

(d) Purine alkaloids

 

6. Ephedra used as……….

(a) Hepatoprotective

(b) Decongestant

(c) Bronchodilator

(d) All of the above

 

7. …….is one of the important diagnostic features of ephedra powder.

(a) Lignified parenchyma

(b) Cork cell

(c) Calcium oxalate crystal

(d) Brown matter

 

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