Dioscorea. Rhizomes with nipponia dioscorea roots

Dioscorea. Rhizomes with nipponia dioscorea roots

Dioscorea. Rhizomes with nipponia dioscorea roots

Specification & Spread

Rhizomes with nipponia dioscorea roots — rhizomata cum radicibus dioscoreae nipponicae
Nipponia dioscorea— Dioscorea nipponica (Makino)
Yam family — Dioscoreaceae
Other names: Japanese dioscorea.

It is a herbaceous perennial plant – dioecious vine: The coiling stems can be 5-7 m long and more.
The rhizome is horizontal, thick, up to 3 cm in diameter, branched, with numerous thin and hard roots, up to 1.5 m long. The leaves are alternate, petiolate, broadly ovate, with a heart-shaped base, arcuate venation. The lower leaves are seven-lobed, with short lateral lobes and a more elongated, large, pointed middle; the upper leaves are three- and five-lobed or with almost no pronounced lobes.
The flowers are dioecious, small, inconspicuous, with a simple six-part yellowish-green perianth, gathered in the axillary rare brush. The fruit is a three-celled wide-ellipsoidal box with three wide membranous wings on the ribs, the seeds are flat and winged.

It blooms in July – August, the seeds ripen in August – October.

Other species of dioscorea

Caucasian dioscorea (Dioscorea caucasica Lipsky) — perennial dioecious herbaceous vine with shoots up to 2.5-3.5 m long. The rhizome is horizontal, thick and long.The lower leaves are whorine, 6-15 cm long, the upper leaves are alternate or opposite, heart-ovate, acuminate, whole, densely pubescent from below. The flowers are small, greenish, in simple axillary spiciform racemes. The fruit is a round, three-sided capsule. The seeds are with a wing surrounding the seed on all sides, almost equally wide around the entire circumference.
It blossoms in May -June, fruits in September.

Caucasian Dioscorea — an endemic plant of the Caucasus, is found mainly in the western part of the Transcaucasus (Abkhazia and the Adler region of the Krasnodar Territory), in the lower forest belt. Due to limited natural resources currently not used.

The promising species is Deltoid Dioscorea (Dioscorea deltoidea Wall.) As a source of diosgenin, from which corticosteroid hormones can be obtained. The country is India, China, Indochina, but the deltoid dioscorea grows well and bears fruit in the conditions of culture even in the climatic conditions of the Moscow region. It is important for industrial tissue culture.

Spreading. Nipponia dioscorea – Far Eastern species. It is widely spread in the Primorsky and Khabarovsk Territories, Amur Region. It is necessary to introduce this plant in culture.

Habitat. It grows in sparse deciduous and mixed forests, forest glades, edges, river valleys, streams and oxbows.The plant is also found on the ground cuttings, fires, on old deposits.


The chemical composition of dioscorea

The rhizomes with Nipponia dioscorea roots contain up to 8% steroid saponins.

The main ones are:

  • protodioscin,
  • protogracillin and
  • dioscin (2.2%), the highest content noted in the budding phase.

The aglycone of these compounds is diosgenin. Diosgenin can serve as a raw material for the synthesis of corticosteroid hormonal preparations (cortisone and progesterone).

In rhizomes of Nipponia dioscorea there are also found:

  • starch and
  • fatty oil.

Harvesting and storage of raw materials

Harvesting. The raw materials are harvested throughout the growing season, starting from late April until late autumn, but to restore the rhizome thickets with roots, it is better to harvest in September-November (after the seeds ripen) when it reaches maximum sizes, although the amount of dioscin is somewhat reduced.

Security measures. It is necessary to leave about ⅓ of plants found at the site for the renewal of thickets. The specimens with a height of less than 1 m are not subject to harvesting; it is recommended to sow seeds or bury rhizome pieces to the place of the dug-out plants. The repeated harvesting on the same site is possible only after 20 years.

Drying. The optimum is drying in dryers at temperatures up to 50 °C. The pre-raw materials are dried under canopies or on currents. The high-quality raw material is also obtained by drying in well-ventilated attics, where it is laid out in layers of up to 10 cm and periodically mixed. It is allowed to dry in the sun.

Storage. The raw materials are stored in boxes and bags.

Whole raw materials are represented by pieces of cylindrical, slightly curved or twisted rhizomes with roots up to 30 cm long and up to 2 cm in diameter. Outside the rhizomes are light brown or yellowish, longitudinally wrinkled, covered with a thin layer of cork, which is usually easily peeled off in the raw materials. On the upper side, the remains of dead stems are clearly visible. From the rhizome there are few elastic thin roots up to 40 cm long and about 1 mm in diameter. The fracture of the rhizomes is smooth, white or cream. The smell is weak and specific. The taste is bitter and slightly burning.

Properties and application

Pharmacotherapeutic group. Hypolipidemic, hypocholesterolemic and hypotensive agent.

The pharmacological properties of dioscorea

Steroid saponins of Nipponia dioscorea inhibit development of:

  • atherosclerosis,
  • hypertension,
  • warn of convulsions.

The infusion and extracts:

  • stimulate motor and secretory activity of the gastrointestinal tract,
  • inhibit the absorption of cholesterol from the intestines.

In the mechanism of the anti-atherosclerotic effect of dioscorea preparations, a stimulating effect on liver function and biliary excretion is important.

Influenced by the Nipponia dioscorea saponins:

  • synthesis of bile acids from cholesterol in liver cells is activated,
  • increased secretion of bile by hepatocytes, cholesterol excretion with bile;
  • the synthesis of hippuric acid is enhanced, which is considered an indicator of activation of the antitoxic function of the liver. Polisponin reduces the adhesion-aggregation ability of platelets, apparently due to the improvement of lipid metabolism in blood cells and vascular endothelium.

Saponins of dioscorea:

  • increase diuresis, without having a damaging effect on the kidneys, and
  • possess antihypertensive properties.

Dioscorea preparations give some X-ray protective effect, increasing the lifespan of irradiated animals.

Application of dioscorea

It is used in complex therapy for general, cerebral and coronary atherosclerosis as a cholesterol-lowering drug, both in the initial stages of atherosclerosis (for prophylaxis) and in case of severe forms of the disease.
The side effects (sweating, loss of appetite, disorders of bowel function, skin itching) are rare. In these cases, reduce the dose or temporarily cancel the preparation.

It is not recommended for patients with bradycardia and pregnant women, as well as individual intolerance.