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Lecture № 13

June 20, 2024

Lecture

Herbs and herbs raw stuff that contain triterpenoid saponins.

Plant materials containing saponins have long been used in many parts of the world for their detergent properties. For example, in Europe the root of Saponaria officinalis (Caryophyllaceae) and in South America the bark of Quillaja saponaria (Rosaceae). Such plants contain a 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 haemolytic properties, and then injected into the blood stream are highly toxic. They can cause the death of cold blooded animals such as frogs, worms and fish even in 1:1000000 dilution. Their molecule consists of the aglycone called sapogenin and carbohydrates (sugars).

According to the structure of aglycone two kinds of saponin are recognised- the steroidal (commonly tetracyclic triterpenoids) and the pentacyclic triterpenoids types. Both of these have a glycosidal linkage at C-3 and have a common biogenetic origin via mevalonic acid and isoprenoid units.

Steroidal saponins

Steroidal saponins are less widely distributed in nature than the pentacyclic triterpenoid type. Sapogenins are derivatives of cyclopentanperhydropenantrene. Some species of Strophantus and Digitalis contain both steroidal saponins and cardiac glycosides.

Steroidal saponins are of great pharmaceutical importance because of their relationship to compounds such as the sex hormones, cortisone, diuretic steroids, vitamin D and the cardiac glycosides. Some are used as starting materials for the synthesis of these compounds.

Triterpenoid saponins

In many triterpenoid saponins oleanolic acid is sapogenin. They are abundant in many dicotyledonous families, particularly the Caryophyllaceae, Sapindaceae, Polygalaceae and Sapotaceae, Ranunculaceae, Papaveraceae, Araliaceae, Rubiaceae and Compositeae. Altogether some 80 families are involved.

Methods of obtaining

For obtaining of saponins from MPM water or diluted alcohols are used. Aglycones are well soluble in organic solvents.

Methods of investigation

There are two types of reactions: according to their physical, chemical and biological properties.

Identification of saponins according to the physical properties:

1) appearing of foam;

2) Fontan-Kandell reaction.

Identification of saponins by their chemical properties:

1) reactions of precipitation;

2) reaction of forming of coloured substances.

Identification by biological properties:

1) definition of haemolytic index.

In these latter days thin-layer chromatography have been widely used for identification of saponins.

Biological action

Saponins stimulate secretion of bronchial glands, enhance cough center and thus are widely used as expectorants. Also they are used as adaptogenic drugs (ginseng, aralia), regulate water-mineral balance (glycyrrhiza), have anti-inflammatory, diuretic and laxative properties. Steroidal saponins are source for production of corticosteroids (cortisone hormones) and in treatment of atherosclerosis.

MP and MPM containing triterpenoid saponins

Radices Glycyrrhizae

Glycyrrhiza glabra- Liquorice root

Fabaceae

Part used. Dried rhizome and roots.

Habitat. Southern Europe, Northern Africa and Western and Central Asia.

Constituents. 5 to 8% of glycyrrhizin, an intensely sweet, water-soluble principle consisting of the potassium and calcium salts of glycyrrhizic acid; glycyramarin (a bitter principle) occurring mostly in the bark; mannite, volatile oil, resin, starch, sucrose, glucose, flavonoid glucosides, calcium oxalate, etc.

Uses. Demulcent, expectorant and flavouring agent. The powdered root is extensively employed as a pill excipient and the fluid extract to disquise the taste of nauseus preparations. Most of the licorice imported is used by the tobacco manufacturers in the flavouring of tobacco. Preparations: Glycyrrhiza extract, Glycyrrhiza syrup, elixir. Glycyrram is used for the treatment of bronchial asthma and kidney disorders. Glycyrrhinol used for trichomonadal colpitis.

Radices Araliae mandshuricae

Aralia mandshurica- Manchurian aralia

Araliaceae

Part used. Dried rhizome and roots.

Habitat. Korea, Russia, China.

Constituents. Volatile oil (0.33%); a glycosidal saponin called araliin; resin (3%), starch, tannin, pectin, sugar, etc.

Uses. Stimulant and diaphoretic. Preparations: tincture and saparal (tablets) are used to treat nervous disorders, hypotension and depression.

Folia Orthosiphonis staminei

Orthosiphon stamineus- Java tea

Lamiaceae

Part used. Dried leaves.

Habitat. Wild Ortosiphon grows in North-East Asia, Australia, Indonesia, cultivated in tropical and subtropical countries.

Constituents. Leaves contain triterpene spononins- α-amyrin derivatives, ursolic acid, flavonoids, ether oil, organic acids.

Uses. Infusion has diuretic properties and employed in treatment of cystitis, gout.

Radices Ginseng

Panax ginseng- Ginseng root

Araliaceae

Part used. The dried root.

Habitat. North-East America- in woodlands, Eastern Asia in mountains.

MPM description. Subcylindrical, somewhat spindle-shaped, fleshy, and frequently2- to several branched in lower portion, up to 12 cm in length and up to 2.5 cm in thickness, the upper portion with a crownshowing one or more stem scars and annulations; lower portion annulated, irregularly longitudinally wrinkled and exhibiting root scars; the external colour varying from yellowish-white to yellowish-brown; fracture short, internally pale yellowish to

yellowish-brown and exhibiting a broad, soft, whitish bark, a dark brown cambium line and a distinctly radiate, hard wood; scattered through the bark and wood are numerous oil and resin canals; odour slightly aromatic, taste sweetish, aromatic, mucilaginous and slightly bitter.

Constituents. Ginseng contains a complex mixture of triterpenoid saponins, these glycosides have been categorised into 3 series- the panaxosides, the ginsenosides, and the chikusetsusaponins. One or more of these groups of glycosides appear to account for the biologic properties of ginseng. It also contains volatile oils, resin, a phytosterin, mucilage, sugar, starch, etc.

Uses. Ginseng is used by the laity as a stimulant and aromatic bitter. The Chinese also employ it as an aphrodisiac and heart tonic but without scientific justification. Ginseng is a favourite remedy in Chinese medicine and is considered to have tonic, stimulant, diuretic and carminative properties. It reportedly reduces the blood glucose concentration and acts favourably on metabolism, the central nervous system, and endocrine secretions. It is employed in the Orient in the treatment of anaemia, diabetes, insomnia, neurasthenia, gastritis and especially sexual impotence. Medicines– tincture, fluid extract, yokhimbe-extract and others.