EPHEDRA

Synonyms :  Ma Huang

Biological Source :  Ephedra  consists  of  the  dried  aerial  parts  of Ephedra  gerardian, Ephedra  sinica, Ephedra equisetina, Ephedra nebrodensis and other Ephedra species, belonging to family Ephadreaceae.

Macroscopy :



Ephedra gerardiana :

 It consists of cylindrical woody stem that is grey or greenish in colour. Nodes, internodes, scaly leaves and terminal buds are present in the stems. The  distance  between  the  internodes  is  3–4  cm  and  the  nodes  bare  the  scaly leaves.  They  are  bitter  in  taste.  The  plant  has  stamens  and  pistils  on  separate flowers; staminate flowers in catkins and a membraneous perianth, pistillate flowers terminal on axillary stalks, within a two-leaved involucre. Fruit has two carpels with a single  seed  in  each  and  is  a  succulent  cone,  branches  slender  and  erect,  small leaves, scale-like, articulated and joined at the base into a sheath.

Ephedra sinica :

Thickness of the stem is 4–7 mm branches are 1–2 mm. Length up to 30 cm of branches and 3–6 cm of internodes. The main stem is brown in colour. Leaves are 2–4 mm long, opposite, decussate and subulate. Leaf, base is reddish-brown,  apex acute  and  recurved  and  lamina  white  in  colour.  A  pair  of  sheathing leaves present at the nodes, encircling the stem and fused at the base.

Ephedra equisetina :

Stems are woodier and more branched 1.5–2 mm. Length 25–200 cm of branches and 1–2.5 cm of internodes, outer surface is grey to pale green and smooth.

Ephedra  nebrodensis : 

The  stems  are  15–35  cm  in  length;  1–2  mm  thick, cylindrical, greenish-yellow in colour, nodes are brownish and distinct and fractured surface is fibrous in the cortex but pith contains brownish powdery mass. The leaves are  brownish  to  whitish-brown  in  colour,  scaly,  connate,  opposite  and  decussate, acute, agreeable and slightly aromatic odour and taste is astringent and bitter.


Microscopy:

The  transverse  section  of  the  ephedra  stem  shows  epidermis,  composed  of  thick-walled,  quadrangular  cells,  covered  by  thick  cuticle.  Cortex  is  composed  of chlorenchyma  with  outer  zone  of  radially  elongated  cells  and  inner  zone of  spongy parenchyma.  Pith  is  large  with  rounded  cells,  containing  dark  brown  mucilaginous substance  in  pigment cells.  The  margin  appears wavy  due  to  ridges. The following tissues are observed from the periphery towards the centre:



i.          Epidermis:

It  is  composed  of  a  single  layer  of  thick-walled,  quadrangular  cells  with  thick  and smooth cuticle. Vertical rows of sunken stomata are present between many vertical ridges of the stem. Papillae are also present in the ridges. Below the ridges, groups of non-lignified fibres are observed.

ii.          Cortex:

It  is  composed  of  two  to  three  layers  of  chlorenchyma  (loosely  arranged parenchymatous  palisade  cells  containing  chloroplasts)  with  outer  layers  of  radially elongated  cells  and  inner  zone  of  spongy  parenchyma.  Cortex  shows  lignified  as well as non-lignified fibres.

Unlignified  fibres  appear  like  a bunch  of  grapes  and  occur  below  the  ridges where no palisade cells are seen. Lignified fibres are found scattered, isolated or in groups  of two  to four. These  occur  in the  inner  layers  of  oval,  cortical  parenchyma which show chloroplasts.

iii.          Pericyclic Fibres:

Pericycle consists of groups of lignified fibres outside the phloem.

iv.          Vascular Bundles:

These  are  around  six  to  ten  in  number  radially  arranged  in  the  cortex.  These  are collateral,  conjoint  and  open.  Phloem  is  towards  the  outer  side  and  appears distinctly. It contains sieve tubes and companion cells. Xylem is well developed consisting of  vessels,  tracheids,  fibro-tracheids  and  parenchyma.  Xylem  from  a  mature  stem shows a well-developed continuous band.

v.          Pith:

It  is  composed  of  large,  thin-walled, lignified  and  polygonal  parenchyma  with intercellular spaces. Some cells contain brownish, mucilaginous masses.


Powder Characterstic :

The  powder  of  ephedra  is  pale  yellowish  brown  with  faint  odour  and  slightly  bitter

taste. It shows the following characters microscopically:

i.          Epidermal Cells :

Entire  cells  and  fragments  of  cells  are  both  observed.  Cells  are  rounded  to quadrangular with thick-ridged outer walls, sunken stomata and papillae.

ii.          Fibres :

Lignified  and  non-lignified  fibres  appear,  which  are  of  uniform  thickness,  long, slender and cylindrical (like glass rods). Entire fibres or fragments of fibres are seen.

iii.          Wood Elements (Xylem):

It consists of tracheids only with bordered pits.

iv.          Brownish Matter:

It originates from pith. It is abundant, mucilaginous and of regular shape and form.


Powder Microscopy of Ephedra Stem


Chemical Constituents:

Ephedra  contains  alkaloids  Ephedrine  (water-soluble  salt  of  an  alkaloid), Pseudoephedrine  (analog  of  ephedrine),  Norpseudoephedrine  (An  analog  of ephedrine).  The  leaves  and  stems  of  ephedra  also  contain  many  potentially  active compounds, such as tannins, saponin, flavone and volatile oils.

7)  Chemical Test:

To the drug (10 mg) in water (1 ml) dilute HCl (0.2 ml), copper sulphate solution (0.1 ml)  and  sodium  hydroxide  solution  (2  ml)  are  added;  the  liquid  turns  violet.  On adding  solvent  ether (2  ml)  and  shaking  vigorously,  the  ethereal  layer  turns purple and the aqueous layer becomes blue.

8)  Uses:

Ephedrine  is  antiallergenic,  antiasthmatic,  antispasmodic,  decongestant,  cough suppressant,  stimulant  and  vasoconstrictor.  Pseudoephedrine  is  decongestant, cough  suppressant  and  norpseudoephedrine  is  peripheral  vasodilator  used  to  treat angina. As a whole it is decongestant; it opens sinuses, increases sweating, dilates bronchioles  (antiasthmatic  use),  diuretic,  CNS  stimulant,  raises  blood  pressure, alleviates aches and rheumatism, alleviates hay fever/colds, etc.