1. Saponin glycosides

2. General characters Widely distributed in higher plants.
Bitter, acrid taste & sternutatory (irritant to mucous membranes).
Form colloidal solutions in H2O  foam on shaking due to: hydrophobic / hydrophilic asymmetry of the molecule (large aglycone & small sugar moiety)  lowering of surface tension in aqueous solution.
Form insoluble complex with sterols.
Destroy RBCs haemolysis.
Toxic to cold- blood animals (fishes & frogs).
Toxic by i.v. injection & harmless by oral route.

3. Chemical characters
O-glycosides  hydrolysis  aglycone (sapogenin) + sugar moiety.
Aglycone:
triterpenoidal (C-30) [mainly in Dicotyledons]
steroidal (C-27) [mainly in Monocotyledons]
Sugar moiety:
Often contain uronic acids or acyl residues.
Usually glycosylation is at C-3.
Sometimes -CH3 (side chain)  -COOH, which may be esterified by a sugar.

4. Isolation Plant material + water, alcohol or aqueous alcohol + reflux.
Concentrate & precipitate crude saponin mixture with:
Ether or acetone.
Lead acetate (acidic saponins), or basic lead acetate (neutral saponins) followed by decomposition with acid.
Individual glycosides are separated by chromatography.

5. Economical & Medicinal importance
Economical uses
Cleaning industrial equipment & fine fabrics.
Powerful emulsifier.
Steroidal sapogenins used in semisynthesis of cortisone & sex hormones.
Medicinal uses
Expectorant
Immunostimulant
Control of schistosomiasis snails
Hypoglycemic (saponins of Balanites aegyptiaca , Egyptian date-sugar)

6. Tests for identification
Froth test:
1 ml of aqueous solution of saponin or plant
extract + shake  persistent & voluminous
froth.
Haemolysis test:
Suspension of RBCs in normal saline + equal
volume of plant extract in normal saline +
shake gently  clear red solution indicating
heamolysis of RBCs (compared with blank ).

7. Quantitative Determination
Gravimetric method
Saponin glycosides + Ba(OH)2  precipitate [Saponin-Ba(OH)2 complex]
Filer, dry & weigh the precipitate  original weight {W1}
Ignite & weigh the residue {W2} (calculated as BaO)
W1 - W2 = Saponin content
Determination of Foam Index
The foam index is defined as:
“ The dilution of the drug, that gives a layer of foam of 1 cm height, when an aqueous solution is shaken in a graduated cylinder for 15 seconds after standing for 15 min.”
Determination of Fish Index
Saponins are toxic to cold blooded animals.
The fish index is defined as:
“The reciprocal of the saponin dilution that kills 60 % of the experimental animals within 1 hour.”
Determination of Haemolytic Index
The heamolytic index is defined as:
“The greatest dilution of saponin that produces complete haemolysis.”

8. Steroidal saponins- Balanites saponins (Balanitins 1-4)
Chemistry
Steroidal saponin glycosides.
Aglycone: yamogenin (furanostane
type).
Source
Fruits & bark of Balanites
aegyptiaca : Balanitins 1-4 &
balanitoside.
Uses
Hypoglycemic, anticancer &
molluscicidal
Balanites aegyptiaca
Fruits

9. Triterpenoidal Saponins - Licorice saponins
Source
Rhizomes & roots of licorice: % of Glycyrrhizin
Glycyrrhizin = mixture of K+ & Ca++ salts of Glycyrrhizic acid
Glycyrrhizic acid  Glycyrrhizinic acid
Structure
Glycyrrhizic acid = Glycyrrhetic
acid -3 O- diglucuronide (2 molecules of glucuronic acid)
Glycyrrhetic acid  Glycyrrhetinic acid

10. Major non-saponin constituents of Licorice
Flavonoid glycosides: major liquiritin (flavanone).
Coumarins: herniarin & umbelliferone.
Others: asparagine, dihydrostigmasterol, glucose, mannitol & starch.

11. Licorice - Uses
Expectorant & demulcent by stimulation of tracheal mucous secretion due to glycyrrhizin.
Antiinflamatory & adrenocorticotropic activity due to steroidal-like activity of glycyrrhizin &/or glycyrrhetic acid.
Antihepatotoxic, antibacterial, antirheumatic, antitumour & antiviral.
Used in treatment of gastric & duodenal ulcers by increasing the rate of healing of gastric mucosa mainly due to liquiritin.
DGL = licorice preparation with very low % of glycyrrhizin (< 1 %) used as antiulcer for hypertensive patients.
Used in laxative formulations to facilitate absorption of anthraquinone glycosides due to surfactant properties of saponins.
Used as sweetener (glycyrrhizin 50 times > sweet than sucrose) & as flavoring agent to mask the bitter taste of some drugs as aloe, quinine & others.

12. Ginseng saponins Source
Roots of Panax quinquefolius (American ginseng) & P. ginseng (Asian ginseng), Araliaceae.
Contains a complex mixture of triterpenoidal saponins with a tetracyclic ( steroids) or pentacyclic structure
Classification
Classified into 3 types:
Ginsenosides,
Panaxosides
Chikusetsusaponins.
Roots
Aerial parts

13. Ginseng saponins Ginsenosides
Major saponins of ginseng (0.7-3 % calculated as ginsenosides).
Aglycones of most ginsenosides have a tetracyclic steroidal structure. They are glycosides of:
20 (S)-protopanaxadiol: aglycone of ginsenosides Rb1, Rb2, Rc, & Rd. Rb1 is the major.
20(S)-protopanaxatriol: aglycone of ginsenosides Re, Rf, Rg1, Rg2 & Rh1. Rg1 is the major.
Ginsenoside Ro is an exception, being a triglycoside of the pentacyclic triterpene (oleanolic acid).

14. Ginsenosides

15. Ginseng -Therapeutic uses
Tonic, stimulant, diuretic & carminative.
Adaptogenic (antistress): enhances body nonspecific resistance to external stress (physical, chemical or biological).
Improves physical & mental performance e.g. learning, memory & physical capabilities.
Improves immune function & metabolism.
Used in anemia, diabetes, insomnia, neurasthenia, gastritis & sexual impotence.
Contraindicated in case of hypertension & during pregnancy.

16. Cyanogenic glycosides

17. Cyanogenetic glycosides
N.B. Cyanogenic = Cyanogenetic= Cyanophore
Introduction
O-glycosides  hydrolysis  HCN gas.
Present in over 3000 plant spp. (110 families).
In plants, cyanogenic glycosides & their hydrolytic -glycosidase enzymes are present in different cellular compartments.
Cyanogenesis: is a chemical defense mechanism protecting plants against damaging organisms by release of toxic HCN gas

18. Cyanogenic glycosides-Structure
-hydroxynitrile derivatives = cyanohydrins.
Fairly unstable, stabilized by -D-linked sugar chains with -D-glucose as first sugar attached to the aglycone.
R1 & R2 are often different pairs of epimers.

19. Cyanogenic glycosides vs. non-cyanogenic nitriles
Glucosides of - & -hydroxynitriles.
On hydrolysis: do not yield free HCN except under specific conditions.
Examples: cyanolipids (esters of fatty acids with
b- & -hydroxynitriles) & Simmondsin

20. Cyanogenic glycosides-Amygdalin
Source
Kernels of peaches, apricots (Prunus armeniaca) & bitter almond seeds (Prunus amygdalus var. amara) [Rosaceae] .
Hydrolysis
Amygdalin + emulsin enzyme (mixture of 3 enzymes:
Amygdalin hydrolase + prunasin hydrolase +
mandelonitrile lyase)  benzaldehyde + HCN + 2 glucose.
Uses
Preparation of benzaldehyde (volatile oil of bitter
almond)
Peaches

21. Amygdalin- hydrolysis

22. Cyanogenic glycosides-Linamarin
Linseed
Source
Seeds of Linum usitatissimum, (Linseed, Flaxseed, Linaceae), Lotus arabicus & in lima beans.
Hydrolysis
Linamarin  acetone cyanohydrin ( acetone + HCN) + glucose

23. Glucosinolates

24. Glucosinolates-General characters
Glucosinolates = Thioglycosides = Isothiocyanate glycosides
Common in Cruciferae (mustard family), Capparidaceae, Resedaceae & Liliaceae.
Bound toxins like cyanogenetic glycosides.
Found in plants with specific hydrolytic enzymes (thioglucosidases= myrosinases).
Characterized by presence of:
One S atom attached to glucose  S-glycoside
Another S atom present as a sulfonated oxime group.
Aglycones: aliphatic or aromatic formed from amino acids.
Members of family Brassicaceae ( = Cruciferae) are rich in glucosinolates:
Oilseeds e.g. rapeseed
Condiments e.g. mustard & horseradish
Vegetables e.g. broccoli, cabbage & turnips

25. Pharmacological action & uses
Broccoli
Rape
Black mustard
Horse radish
Cabbage
Turnip
Pharmacological action & uses
Play an important role as feeding deterrent against insects & mammals.
Anticarcinogenic.
Improve flavor of foods.

26. Glucosinolates - Sinigrin
Source
Seeds of Brassica nigra (black mustard) [Brassicaceae]
Properties
Sharp odor & biting taste.
Hydrolysis
Sinigrin + myrosinase enzyme  allylisothiocyanate (volatile oil of mustard) + KHSO4 + glucose.
Uses
Internally: emetic.
Externally: local irritant, rubefacient & vesicant.
Commercially: condiment.

27. Glucosinolates - Sinalbin
Source
Seeds of Brassica alba (white mustard), Brassicaceae.
Hydrolysis
Uses: Condiment

28. Non-glycosidic organo-sulfur drugs- Alliin
Source & decomposition
Bulb of Allium sativum (Fam. Liliaceae)
Food & traditional medicine since Pharaohs.
Intact cells of garlic contain Alliin (1.2 % in fresh garlic).
Alliin + crushing (allinase enzyme)  Allicin (diallyl thiosulfinate).
Allicin is responsible for the characteristic odor & flavor of garlic.
Allicin + air + water  diallyl disulfide + diallyl trisulfide + polysulfides (All strong smelling).
Uses: Allicin is used as antibacterial, antihyperlipidemic; inhibits platelet aggregation & enhances the blood fibrinolytic (anti-thrombic) activity.