STROPHANTHUS, a genus of plants of the family Apo cynaceae, deriving its name from the long twisted thread-like segments of the corolla, which in one species attain a length of 12 to 14 inches. The genus comprises about 28 species, mainly tropical African, extending into South Africa, with a few species in Asia, from Farther India to the Philippines and China. Several of the African species furnish the natives with the principal in gredient in their arrow poisons—S. hispidus and S. kombe being probably most frequently employed.
Both S. hispidus and S. kombe have hairy seeds with a slender thread-like appendage, terminating in a feathery tuft of long silken hairs, the seeds of the former being coated with short appressed brown hairs, and those of the latter with white hairs; but in the species used at Delagoa bay and called "umtsuli" the thread-like appendage of the seed is absent. The natives pound the seeds into an oily mass, which assumes a red colour, portions of this mass being smeared on the arrow immediately behind the barb.
Under the name of strophanti semina, the dried ripe seeds of Strophanthus, freed from awns, are official in the British and many other pharmacopeias. The seeds must be mature. They are about in. long, 6 in. broad, greenish fawn, covered with flattened silky hairs, and oval-acuminate in shape. They are almost odourless, but have an intensely bitter taste. The chief constituent is a white
microcrystalline glucoside, known as strophanthin, freely soluble in water and alcohol, but not in chloroform or ether, and melting at about 173° C. It constitutes about 50% of the mature cotyle dons of the mature seed. The resin is contained in the husk, and occurs in the alcoholic tincture of strophanthus.
Pharmacology.—The drug has no external actions. Taken in ternally it tends, after the repetition of large doses, to produce some gastric irritation. As ordinarily administered, the drug acts on the heart before influencing any other organ or tissue. It is almost certain that strophanthus acts directly on no other cardiac structure than the muscle-fibre. No action can certainly be demonstrated either upon the vagus nerves or upon the intra cardiac nervous ganglia. The muscular force is increased in a very marked degree. A secondary consequence of this is that the dia stole is prolonged, and the pulse thus rendered less frequent. If the heart is beating irregularly the drug tends to make it more regular. In fatal cases of strophanthus poisoning death is brought about by the arrest of the heart in systole, i.e. in a state of tetanic spasm from over-stimulation. Strophanthus markedly raises the blood-pressure, but this action is almost entirely due to the increased force of the heart.