Strophanthus

STROPHANTHUS

Synonyms

Kombe Seeds, Strophanti Semina, Semen Strophanthi, Strophanthus Seeds.

Biological Source

Strophanthus consists of dried ripe seeds of Strophanthus kombe Oliv. deprived of their awns belonging to family Apocynaceae.

Geographical Source

It is mainly found in East Africa near lakes of Nyasaland and Tanganyika, Portuguese, Cameroon. The tribal are using this seeds as arrow poison.

Cultivation and Collection

The plants are large, woody climbers, climbing on the large trees in the forests of Africa. Fruit consists of two divergent follicles which are dehiscent and many seeded. Each follicle is 30 cm long, 2.5 cm broad, tapering both at the apex and base. Mature and ripe fruits are collected in the month of June–July. After collection epicarp and fleshy mesocarp are removed and seeds separated from yellow-brown leathery endocarp and awns. Seeds are washed and dried. The seeds are derived from anatropous ovules.

Characteristics

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, flat-tened 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. Kombe) bearing on one side a ridge running from about the centre to the summit; fracture short and somewhat soft, the frac-tured surface whitish and oily; odour heavy when the seeds are crushed and moistened; taste very bitter.

Microscopy

Epidermis consists of elongated, polygonal, tabular cells and lignified covering trichomes. Next to epidermis collapsed layer of parenchyma cells are present that contain calcium oxalate crystals. Thin walled endosperm contains aleurone grains and fixed oil.

Chemical Constituents

The drug contains 8–10% cardiac glycosides known as k-strophanthin. k-strophanthin is a mixture of three gly-cosides, cymarin, k-strophanthin P and k-strophanthoside, which differ only through attached sugars and on hydrolysis yields same aglycone strophanthidin. It contains a sugar cymarose that is methoxy digitoxose which gives positive reaction for Keller–Killiani test. The drug also contains mucilage, resin, fixed oil, choline, trigonelline, and kombic acid—an acid saponin.

Uses

The use of strophanthus in medicine is for its influence on the circulation, especially in cases of chronic heart weakness. As its action is same as that of digitalis, 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. Unlike digitalis it has no cumulative property.

Substituents and Adulterants

The S. kombe is commonly adulterated with S. hispidus, S. nicholsoni, S. gratus, S. courmontii, S. emini, S. sarmentosus, etc.

S. hispidus has a shape, colour, similar to that of the S. kombe, it consist of k- strophanthin. S. nicholsoni has a whitish seed; the trichomes form a tangled surface covering. The calcium oxalates are absent in both embryo and the seed coats. S. gratus are brown in colour, and has a glabrous appearance to the naked eyes. It reveals the presence of small warty trichomes when observed under the microscope. S. courmontii has a brownish tinge and has a similar character to that of the genuine drug. It can be distinguished due to its small size, lanceolate shape and less bitter taste.