Saponins (PDF)
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Uploaded by EntrancedAstronomy
University of Babylon
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This document provides comprehensive details about saponins, their properties, and classifications into steroidal and triterpenoidal types. It further covers the wide range of applications from food materials to medicine. It also touches on important aspects such as the isolation techniques and tests for identification of saponins.
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Saponin glycosides Saponins are a group of glycosides which is widely distributed in the higher plants. These are plant glycosides possessing a distinct property of forming soapy lather in water. Therefore, they are largely used as detergents. The aglycones of this glyco...
Saponin glycosides Saponins are a group of glycosides which is widely distributed in the higher plants. These are plant glycosides possessing a distinct property of forming soapy lather in water. Therefore, they are largely used as detergents. The aglycones of this glycosides are referred to as sapogenins. This group of plants glycosides have two common characteristics: 1- They foam in aqueous solution upon shaking, therefore they are called saponin (from latin: sapo,soap) 2- They cause hemolysis of red blood cells when injected into blood stream, but when taken by mouth saponins are comparatively harmless. Some of our valuable food materials contain significant amount of saponins eg. Beans, lentils عدس, soybeans, spinach and oats الشوفان. Toxicity is minimized during ingestion by low absorption and by hydrolysis. Properties ▪ Saponins are mostly amorphous in nature, soluble in alcohol and water, but insoluble in non-polar organic solvents like benzene, n-hexane, etc. ▪ Saponins form colloidal solution in water (hydrophilic colloids) which froths upon shaking. These substances modify and lower the surface tension. This has led to their use it as foaming agent ▪ In general, they have a bitter, acrid taste and drugs containing them causing or producing sneezing and irritating to the mucous membranes of eyes and nose. ▪ Saponins have also been used in medicine, foaming agents, detergents, powerful emulsifiers of certain resins and fixed oils in fire extinguishers and fish poisons. ▪ Saponins are toxic especially to cold-blooded animals e.g. frogs. Many are used as fish-poisons Properties Saponins have a high molecular weight and their isolation in a state of purity presents some difficulties. Much of the research conducted on the saponin- containing plants was used to discover precursors for steroid hormones as cortisone Structure of Saponins: According to the structure of the aglycon or sapogenin, saponins can be classified into either 1- Neutral saponins: steroidal commonly tetracyclic triterpinoids, C-27).. 2- Acid saponins: are pentacyclic triterpenoid,C-30). Both types of saponins have the glycosidic linkage at position 3. Lead subacetate (Basic lead acetate), Pb3(OH)4(CH3COO)2 Lead(II) acetate (lead diacetate), Pb(CH3COO)2 A. Steroidal or Tetracyclic triterpenoid saponins C27 The steroidal saponins are less widely distributed in nature than pentacyclic triterpenoid type. Steroidal saponins are of great pharmaceutical importance because of their relationship to compounds such as the sex hormones, cortisone, vitamin D and cardiac glycosides. and the most important plant steroid for the partial synthesis of steroid hormones are: diosgenin, botogenin, hecogenin, and so on. Examples: (a) Dioscorea bark- Diosgenin (b) Agave sisalana - Hecogenin (c) Asparagus roots- Sarsapogenin Until 1970 diosgenin isolated from the Dioscorea mexicana bark was the sole source for steroidal contraceptive manufacture. With the nationalization of the Mexican industry, however, prices were increased to such an extent that manufacturers switched to hecogenin for corticosteroids, to other sources of diosgenin and to the use of the steroidal alkaloids of Solanum species. Total synthesis also became economically feasible and is now much used. Sisal (Agave sisalana) Sisal leaves contain hecogenin used in the partial synthesis of the drug cortisone the juice of Agave sisalana leaves presents great ethnopharmacological importance because it is used as an antiseptic in the topical treatment of skin diseases as well as a poultice on wounds. Orally, it is used to treat indigestion, flatulence, jaundice, constipation, and dysentery Different species of Sarsaparilla contain one or more steroidal saponins. Two isomeric genins are known: smilagenin and sarsasapogenin. Sarsaparilla is indicated for the treatment of psoriasis and eczema, and rheumatoid arthritis. Its action would appear to arise from the steroid content of the roots. The genins are used in the partial synthesis of cortisone and other steroids. pentacyclic triterpenoid (C 30) a- The triterpenoidal saponin glycoside, glycyrrhizin, is the main sweet principle of liquorice. b- Beside being a valuable flavouring and sweetening agent, liquorice has demulcent, expectorant and antispasmodic action. All these activities attributed to the saponin, glycyrrhizin. C- Recently, glycyrrhizin was shown to be effectively in gastric ulcer treatment and have a cortisone like action in rheumatic arthritis and other inflammatory diseases.