STROPHANTHUS 169 



kill a normal frog of about 25 gm. weight within an hour when injected into 

 the dorsal lymph sac. The amount required has been designated a 'unit.' 

 The seeds or their preparations may be compared in activity by determining 

 experimentally the quantity that represents a unit. 



Uses. The action of strophanthus seed, which is due to the 

 strophanthin they contain, resembles that of foxglove leaves. It 

 raises the blood-pressure, is an efficient diuretic, and a powerful 

 cardiac poison. It is not cumulative, and less liable than foxglove 

 to produce gastro-intestinal irritation ; hence is sometimes substituted 

 for foxglove when this remedy has failed or disagreed. 



Varieties. The official strophanthus seed often occurs in commerce 

 mixed with or replaced by the seeds of other species of Strophanthus 

 which resemble them more or less closely. The following are the 

 most important. 



8. hispidus, de Candolle. The seeds of this species are exported 

 from West Africa ; they are smaller than the official, although similar 

 in shape, are brownish in colour, bear scattered hairs, and give with 

 sulphuric acid a green reaction. They contain strophanthin (h- 

 strophanthin ; see below) said to be closely allied to, if not identical 

 with, the amorphous strophanthin of Kombe seed. 



S. Courmontii, Sacleux. This is an East African species ; the 

 seeds usually have a brownish tinge, but often closely resemble the 

 official, from which, however, they may be distinguished by their 

 rather smaller size, lanceolate shape, less bitter taste, red reaction 

 with sulphuric acid, and abundant prismatic calcium oxalate crystals 

 in the seed-coat. The active constituent is unknown. The seeds are 

 said to be about one-fourth as active as Kombe seeds. 



S. Nicholsoni, Holmes. The seeds of this species are whitish and 

 woolly, the hairs project beyond the apex of the seed, and the reaction 

 with sulphuric acid is red ; they have been exported from Natal. 

 The active constituent is unknown. 



S. gratus, Franchet. The seeds are brown and glabrous ; they 

 give a red reaction with sulphuric acid, and contain the glucoside 

 ouabain, which was first isolated from the wood of Acokanthera 

 Schimperi, Oliver, and is much more toxic than strophanthin. For 

 this glucoside the distinctive name of ' ^-strophanthin ' has been 

 proposed (Thorns, 1900) ; its use has been advocated as a substitute 

 for the official drug, as the seeds are readily obtainable and easily 

 recognised. 



S. Emini, Aschers. The seeds are greyish green, but they contain 

 cluster crystals of calcium oxalate, and give a red reaction with 

 sulphuric acid. They contain the glucoside e- strophanthin (Thorns), 

 which is distinct from the strophanthin of Kombe seed (&-strophanthin) 

 and also from that of the seed of 8. hispidus (h- strophanthin). Their 

 action on the heart is said to be slight. 



