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Pharmacognosy I
Mosul University/ college of Pharmacy
L.A. Dilbreen Barzanji
Introduction
 Plant materials containing saponins have long been used in
many parts of the world for their detergent properties.
 For ex. In Europe the root of Saponoria officinalis and in
South America the bark of Quillaja saponoria.
 Such plants contain high percentage of glycosides known
as saponins (Latin sapo, soap) which are characterized by
their property of producing a frothing aqueous solution.
 They also have hemolytic properties, and when injected
into the blood stream, are highly toxic.
 The fact that a plant contains hemolytic substances is not
proof that it contains saponins.
 When taken by mouth, saponins are comparatively
harmless.
 Saponins have a high molecular weight and a high
polarity and their isolation in a state of purity presents
some difficulties.
 As glycosides they are hydrolysed by acids to give an
aglycone (sapogenin) and variuos sugars and related
uronic acids.
 According to structure of aglycone or sapogenin, two
types of saponins are recognized:
1. Steroidal (commonly tetracyclic triterpenoids)
2. Pentacyclic triterpenoids saponins
Steroidal saponins
 The steroidal saponins are less widely distributed in nature
than the pentacyclic terpenoid type.
 Steroidal saponins are of great pharmaceutical importance
because of their relationship to compounds such as the sex
hormones, diuretic steroids, vitamin D and the cardiac
glycosides.
 As with other cardiac glycosides, the steriochemistry of the
molecule is of some importance.
 Natural sapogenins differ only in their configuration at
carbon atoms 3, 5 and 25.
Natural steroids for the
production of pharmaceuticals
 Although total synthesis of some medicinal steroids is
employed commercially , there is also a great demand for
natural products which will serve as starting materials for
their partial synthesis.
 Hecogenin with C-ring substitution provides a practical
starting material for the synthesis of cortecosteroids,
whereas diosgenin is suitable for the manufacture of oral
contraceptives and the sex hormones.
 Diosgenin can also be used for cortecosteroid synthesis by
the employment of a microbial fermentation (at a suitable
stage in syntheisis) to introduce oxygen into the 11 αposition of pregnene nucleus.
Dioscorea species
 Tubers of many of the Dioscoreas (yams) have long
been used for food, as they are rich in starch. In
addition to starch some species contain steroidal
saponins, others alkaloids.
 Form a suitable source the sapogenins are isolated by
acid hydrolysis of saponin.
 Previous fermentation of the material for some 4-10
days often gives a better yield.
 The water-insoluble sapogenin is then extracted with a
suitable organic solvent.
 Both wild and cultivated plants are used.
 According to the species, the tubers reach maturity in
3-5 years and on average, yeild 1-8% total sapogenin.
 Until 1970 diosgenin isolated from the Maxican yam
was the sole source of contraceptive manufacture.
 China is now exporting large quantities of diosgenin; it
is of high quality and reasonably priced.
 Three of many Dioscorea species found in China and
used commercially.
Ginseng
 For some 2000 years the roots of Panax
ginseng have held an honored place in
Chinese medicine.
 Today it is a product of world wide
usage.
 Production is principally confined to
China, Korea and Siberia, although it is
cultivated commercially in other
countries.
 The most expensive ginseng is that
derived from Korean root.
 White ginseng is obtained by sun drying of the root after
removal of the outer layers.
 Red ginseng is obtained by first steaming the root,
followed by artificial drying then sun drying.
 Rootlets are numerous on the lower surface of white
ginseng but normally absent from red ginseng.
 The roots are graded and packed.
 The scraping of the roots before drying would appear to be
disadvantageous because histochemical tests and GLC
analysis is show the active saponins to be located outside
the root cambium.
Constituents of Ginseng roots
 Panax ginseng roots have been thoroughly studied by
modern methods of analysis and, of many compounds
isolated , the medicinal activity appears to reside largely in
a number of dammarane-type saponins termed
ginsenosides by Japanese researchers and panaxosides
by Russian researchers .
 These two series of compounds all now generally termed
ginsenosides, are glycosides respectively derived from the
diol 20(S)-protopanaxadiol and the triol 20(S)protopanaxatriol.
 Acid hydrolysis of these saponins involves ring closure of
the aglycone giving either panaxadiol or panaxatriol.
 Glucose is the principal sugar involved with some
input of arabinose and rhamnose.
 Some 30 ginsenosides have been named.
 The BP/EP specifies a minimum of 0.40% for the sum
of ginsenosides Rg1 and Rb1.
 Two other groups of compounds present in the root which
have known therapeutic activity are high molecular weight
polysaccharides (glycans) and acetylenic compounds.
 The glycans of Panax ginseng have been named panaxan
(A-U).those glycans tested have hypoglycemic, antiulcer,
and immunological properties.
 A considerable number of mainly C17, but also C14,
polyacetylenic alcohols have been isolated from the roots
called panaxynol and panaxydol. These compounds have
shown antitumer properties.
Uses
 In Asia, it used in the treatment of anaemia, diabetes,
gastritis, sexual impotence and the many conditions
arising from the onset of old age.
 In the west, it has in recent years become an extremely
popular remedy particularly for the improvement of
stamina, concentration, resistance to stress and to
disease; in this sense of action of the drug is described as
‘adaptogenic’.
 Many ‘ginsneg’ products are available as OTC products
either for oral administration or as cosmetic preparation.
Pharmacognosy I
Mosul University/ College of Pharmacy
L.A. Dilbreen Barzanji
Pentacyclic triterpenoid saponins
 This particular class of saponin essentially contains the
sapogenin component with pentacyclic triterpenoid
nuecleus, that is eventually linked with either sugar or
uronic acids.
 The sapogenin may further may be further classified
into three major categories namely: α- amyrin, βamyrin and lupeol.
 Plant materials oftain contain these these saponins in
considerable amounts. Thus, primula root contains
about 5-10%; liquorice root about 2-12% of glycerrhizic
acid (and a correspondingly larger amount of
glycerrhizin, the potassium calcium salt); quillaia bark
up to about 10% of the mixture known as ‘commercial
saponin’ ; the seeds of horse chestnut up to 13% of
aescin.
 As some plants contain more than one saponin and
purification is often difficult.
Liquorice root
 The pharmacopoeial drug is now defined as the dried
unpeel or peeled, whole or cut root and stolons of
Glycerrhiza galbra.
 In Western Europe liquorice is cultivated, but the ‘Russian’
and ‘Persian’ drugs are obtained from wild plants. In China,
large-scale cultivation is replacing collection from wild.
 The underground organs are developed into sufficient
extent by the end of the third or fourth year, when they are
dug up and washed, some are peeled and cut up into short
lengths before drying, but much is now used unpeeled.
 Glycerrhiza ows most of its sweet taste to glycerrhizin,
the potassium and calcium salts of glycerrhizinic acid.
 Glycerrhizinic acid is the diglucouronic acid of
glycerrhetic (glycerrhetinic)
tritepenoid structure.
acid,
which
has
a
 The yellow colour of liquorice is due to flavonoids, which
have antigastric effect, example of liquorice flavonoids:
liquirtin.
 Other active constituents of liquorice are polysaccharides
with a pronounced activity on the reticuloendothelial
system. e.g. glycerrhzan has been characterized as the
representative polysaccharide with immunological
activity.
 The roots also contain about 5-15% of sugars (glucose,
sucrose).
Action and uses of liquorice
 Liquorice has been long been employed in pharmacy
as a flavouring
expectorant.
agent,
demulcent,
and
mild
 The recognition of the deoxycortecosterone effects of
liquorice extracts and glycerrhetinic acid has led to its
use for the treatment of rheumatoid arthritis,
Addison’s disease and various inflammatory
conditions.
 Unlike cortisone, liquorice may give symptomatic
relief from peptic ulcer pain.
 It has been reported that glycerrhizin gel can act as a
useful vehicle for variuos drugs used topically; not only
are the anti-inflammatory and antiviral effects relevant
but also glycerrhizin enhances skin penetration by the
drug.
 Excessive consumption of liquorice leads to
hypertension and hypokalaemic alkalosis.
Ivy
 The drug consists of the
whole or cut aerial
leaves of Hedera helix,
collected in the spring.
This familiar climber and
creeper is widely
distributed throughout
Europe and Asia.
 Important constituent of ivy are saponins involving
the pentacyclic triterpenoid genins: hederagenin,
bayogenin and oleanolic acid.
 The BP/EP requires a minimum concentration of 3.0%
heteracoside C.
 Like most saponins, those of ivy are toxic in excess
causing diarrhea, vomiting and allergy.
Uses of ivy
 Ivy-leaf extract have been traditionally
used as an expectorant for the treatment
of various chest conditions, such as
bronchitis and whooping cough; also for
gout and rheumatic pains.
 Externally ivy is used cosmetically and
for a various of skin conditions.
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