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.
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