2.3.4.1 Allied Drugs
G-Strophanthin
Synonyms Ouabain; Gratus strophanthin; Acocantherin; Gratibain; Astrobain; Purostrophan; Strophoperim; Strodiral.
Biological Source G-Strophanthin is obtained from the seeds of Strophanthus gratus (Wall & Hock)Baill. It also occurs in the wood of Acokanthera ouabio Cathel and A. schumperi belonging to the family Apocynaceae.
Geographical Source The wood is grown in Ethiopia and Somaliland.
Chemical Constitutents The seeds contain the glycoside G-strophanthin (or Ouabain) as given below:
Ouabain on hydrolysis gives rise to an aglycone termed as G-strophanthidin (or Ouabagenin) and L-rhamnose as the residual sugar moiety.
Description G-Strophanthin mostly occurs as colourless small shining crystals, which are odourless and have an extremely bitter taste. It is readily affected by light, but is quite stable in air. It is practically insoluble in ether, chloroform and ethyl acetate, whereas it is sparingly soluble in cold water (1:75); freely soluble in hot water and alcohol (1:100).
Chemical Tests
1. Mix a few crystals of oubain with a mixture of conc. H2SO4 and water (4:1), the appearance of a brownish red colour, which deepens slowly and ultimately shows a green fluorescence.
2. Froehde’s Test: Mix a few crystals with a drop of Froehde’s reagent, evaporate to dryness, cool and add a drop of H2SO4—the development of a blue colour takes place.
3. Mandalin’s Test: Moisten a few crystals with Mandalin’s reagent, evaporate to dryness, cool and then add one drop of conc. H2SO4—the appearance of a green colour ocurs.
Uses
1. It is an important cardiotonic, which is usually administered intravenously in acute cardiac failure, due to its inherent rapid onset of action.
2. It is invariably employed as a ‘reference standard’ for comparison of cardiac glycosides.
3. It also exerts diuretic action.
