StrophanthusBotanical Name: Strophanthus Kombé (OLIV.)
Family: N.O. Apocynaceae
Synonyms: Strophanthus hispidus. Kombé Seeds. Strophanti Semina.
Part Used: Dried, ripe seeds, deprived of their awns.
Habitat: Tropical East Africa.
Description: The name Strophanthus is derived from the Greek strophos (a twisted cord or rope) and anthos (a flower), thus expressing the chief peculiarity of its appearance, the limb of the corolla being divided into five, long, tail-like segments. The official description of the seeds is 'lance-ovoid, flattened and obtusely-edged; from 7 to 20 mm. in length, about 4 mm. in breadth, and about 2 mm. in thickness; externally of a light fawn colour with a distinct greenish tinge, silky lustrous form, a dense coating of flat-lying hairs (S. Kombé) or light to dark brown, nearly smooth, and sparingly hairy (S. hispidus), bearing on one side a ridge running from about the centre to the summit; fracture short and somewhat soft, the fractured surface whitish and oily; odour heavy when the seeds are crushed and moistened; taste very bitter.'
In Germany the seeds of S. hispidus are preferred because of their guaranteed purity. This plant when growing alone is in the form of a bush, but is usually found as a woody climber inhabiting the forests between the coasts and the centre of the African continent. It then reaches to the tops of the highest trees, coiling on the ground and hanging in festoons from tree to tree. The stem is several inches in diameter. The flowers are creamcoloured, yellow at the base, purple-spotted above.
The British, French and Swiss officially favour S. Kombé, while the United States Pharmacopoeia recognizes both. There is a voluminous literature on the subject.
The seeds of all species of the genus possess hairs that have a characteristic, thickened base, somewhat like those of nux vomica seeds; those of several species are used for the preparation of arrow poison in Africa, at Kombé in the Manganja country, in the Gaboon district, and in Guinea and Senegambia. In Gaboon the poison is called inée, onayé, or onage. Some of the poisons closely resemble those of the genus Acocanthera, which are used for a similar purpose. The plant yielding the arrow poison of Komb‚ was first brought to Europe by Sir John Kirke, and described as a new species by Oliver, of Kew, under the name of S. Kombé. In preparing the arrow poison, the seeds, deprived of their hairs, are pounded to a pulp, the adhesive sap of another plant is added, and the mixture smeared for 6 inches along the point of the arrow. Game wounded by such an arrow is said to be rarely able to move 100 yards, while the flesh can be eaten without bad effect.
Strophanthus is found in commerce either in pods or as clean seeds. It must be preserved in tightly-closed containers, adding a few drops of chloroform or carbon tetrachloride from time to time, to prevent attacks by insects.
The usual course for the qualitative examination has been found insufficient, and a supplementary microscopical test is recommended. The question of its relative variability of strength as compared with digitalis is not definitely settled.
The seeds are reduced to powder with great difficulty. They are sometimes bruised in an iron mortar with broken glass, after drying.
As the active principle of Strophanthus is most abundant in the seeds, but is also found in the husks and hairs, pharmaceutical preparations of the drug should be made from the separated seeds, while other parts may be employed for the manufacture of Strophanthin.
Constituents: A glucoside, Strophanthin, an alkaloid, Inoeine, and fixed oil.
Sulphuric acid, diluted with one-fifth of its volume of water, colours the endosperm, and sometimes the cotyledons, dark green (presence of Strophanthin).
Herr Lampart and Müller received the Hagen Bucholz prize of the German Apothecaries Society for the proposed assay method following, based upon the preliminary extraction of the drug with absolute alcohol, the removal of oil from the precolate with petroleum ether, the conversion of the glucosides into strophanthidin by boiling with hydrochloric acid, and the subsequent extraction with chloroform, weighing, and calculating to strophanthin by multiplying by the factor 2.187.
The strophanthins from different species were found to vary somewhat in chemical composition, and Thoms proposes to name them as follows: k-strophanthin when obtained from S. Kombé, g-strophanthin when obtained from S. gratus, e-strophanthin when obtained from S. Emini, h-strophanthin when obtained from S. hispidus.
g-strophanthin is the one appearing to be identical with the glucoside Ouabain of Acocanthera.
Strophanthinum, a mixture of glucosides prepared from S. Kombé, is a whitish, crystalline powder freely soluble in water and giving a green coloration with sulphuric acid. Warmed with dilute acids it is readily hydrolized into Strophanthidin and a sugar.
Great care must be used in tasting it, and then only in very dilute solutions.
Medicinal Action and Uses: The sole official use of Strophanthus in medicine is for its influence on the circulation, especially in cases of chronic heart weakness. As its action is the same as that of digitalis, although more likely to cause digestive disturbances (Many practitioners are of opinion that Strophanthus does not cause digestive disturbances. - EDITOR), it is often useful as an alternative or adjuvant to the drug. Believed to have greater diuretic power, it is esteemed of greater value in cases complicated with dropsies.
In urgent cases, the effects upon the circulation can be obtained almost immediately by means of the intravenous injection of its active principle. The hypodermic injection of Strophanthin is not recommended, owing to the intense local irritation it causes, and because of its strength it should be used with great care and under medical direction.
Dosages: Of Extractum Strophanthi of the B.P., from 1/4 to 1 grain. This extract takes the place of a solid preparation and can be administered in pills and capsules, 1 grain being equal to 5 minims of the United States tincture.
Of tincture of Strophanthus, B.P. and U.S.P., 5 to 15 drops.
Of Strophanthin, 1/200 of a grain.
The maximum daily dose should not exceed: For g-strophanthin, intravenously, 1/64 grain; by mouth, 1/2 grain. For k-strophanthin, intravenously, 1/40 grain; by mouth, 1/20 grain.
Poisonous, if any, with Antidotes: The greatest caution should always attend the use of strophanthin, though, unlike digitalis, its effects are not cumulative.
Varieties and Substitutions: There are twenty-eight recognized species of the genus in Africa and Asia, extending to China, the East Indies and the Philippines. The commercial drug is often largely compounded of other than the recognized species, and may contain the seeds of related varieties, especially those of Kickxia (Funtumia) africana, which are beardless and spindle-shaped. They turn brown, then red, instead of green, when treated with concentrated sulphuric acid.
S. Kombé grows solely in East Africa, but the seeds from different regions are often mixed before they are shipped.
S. hispidus, S. glabra, S. Emini, S. courmontii (both var. Kerkii and var. Fallax), S. gratus of Sierra Leone, and S. Nicholsoni, all contribute seeds.
The two most mixed with the official drug before exportation are those of S. gratus from the Senegal and Congo, where S. hispidus is found, and which are recommended by some authorities because easily recognized and yielding strophanthin readily in crystalline form, and S. Thallone.
At present Strophanthus seeds are less mixed than formerly. In 1892 the commercial seeds were classified as follows:
1. The official products of S. Kombé and S. hispidus, which contain strophanthin and no crystals of calcium oxalate.
2. Those resembling the official seeds, but coming from Mozambique and Sierra Leone.
3. Those containing calcium oxalate crystals but no strophanthin (from Senegal Lagos, Niger, German East Africa, Togoland, and Baol of Senegal).
4. A very hairy seed from the Upper Niger, varying from a silky white to brown; the embryo contains calcium oxalate crystals, but the seeds do not contain strophanthin.
5. Seeds said to be glabrous, but having hairs in the region of the raphe, come from Lagos and Zambesi and contain neither calcium oxalate crystals nor strophanthin.