Specification & Spread
Foxglove leaves — folia digitalis
Purple foxglove — digitalis purpurea
Figwort family — scrophulariaceae
Other names: yellow foxglove - digitalis grandiflora
Purple foxglove is a biennial in culture and perennial herbaceous plant in nature from 50 to 120 cm tall. In the first year, only the rosette of large bottom sand leaves with an oblong-ovoid shape, with a blunt tip lid and a long winged petiole, with a crenulate edge and reticular venation (well visible from the underside) is developed. In the second year, silvery from pubescence stems are formed, with alternate leaves and a truss of large thimble-like flowers.
Leaves. The lower stem leaves are long-petiolate, ovate; the medium leaves are short; the upper ones are sessile and ovate-lanceolate.
The corolla of the flower is purple, inside is white with purple spots in the fauces. It looks like a thimble.
The inflorescence is a thick, one-sided, multiflorant truss.
The fruit is a bilocular polyspermic seed box.
It blooms in June - July, the seeds ripen in July - August.
Yellow foxglove is a perennial herbaceous plant 40-120 cm tall.
It differs from purple foxglove with lanceolate or oblong-lanceolate, bare, green on both sides of the leaves with uneven edge, as well as light yellow flowers.
It blooms in June - July, the fruits ripen in July - August. Both plants are poisonous.
Spreading. Purple foxglove naturally grows in the forests of Western, Central and Northern Europe. It is cultivated in many countries of the world; in Russia - in the North Caucasus. Also it is possibly cultivated in Ukraine and Moldova.
Domestic varieties significantly inferior to the best foreign varieties in the number of cardenolides.
Yellow foxglove grows in the mountains of the Middle and Southern Urals, in the Carpathians, in the North Caucasus, less often - on elevations in the middle zone of the European part of Russia (Valdai, Volga Upland, etc.). It grows in deciduous and mixed forests in open areas, among bushes, along roads. The resources are poorly studied, and nowadays the raw materials of wild plants are practically not harvested. It is included in the regional Red Books.
More than 60 cardiotonic glycosides were isolated from the aerial part of the purple foxglove.
The most important are purpureaglycosides A and B, having as a carbohydrate component, three molecules of digitoxose and one molecule of glucose;
aglycone purpureaglycoside A - digitoxigenin, purpureaglycoside B - gitoxigenin (16-oxydihydrogenase).
It also contains:
- gitoksin and others.
In addition, the plant found steroid saponins (digitonin, etc.), flavonoids, choline and other compounds.
The leaves of yellow foxglove contain cardiotonic glycosides, the main of which are digilanides A, B, C. In addition, steroid saponins and flavonoids have been found.
Harvesting and storage of raw materials
Harvesting. On the plantations, the rosette leaves of the first year of life are cut off in July-August, and after 1-1.5 months it makes the second, sometimes the third harvesting.
The stem leaves from plants of the second year of life are cut by hand. The raw materials are recommended to be collected in the flowering stage and on a sunny day, as glycosides are accumulated more intensively in the light.
While cultivating foxglove as an annual crop, the leaves are cut 2-3 times per summer without petioles (it makes drying difficult, and do not contain biologically active substances).
Security measures. On biennial plantations while harvesting the raw materials, the root system is protected from damage.
Drying. To dry the raw materials should be quickly. The collected leaves are delivered immediately in an open container to the place of drying. Dry the raw materials in dryers with artificial heating at a temperature of 55-60 °C.
Purple foxglove is used in the form of whole and milled raw materials, as well as powder, yellow foxglove is used only as a whole raw material.
Storage. All raw materials must be well packaged. Close packing promotes better preservation of biologically active substances. Whole raw materials are stored in a dry and dark place. The powder is in ampoules or tightly closed vials. Selected pure glycosides are stored in List A, the remaining preparations and medicinal raw materials are in List B. The biological activity of the raw materials is monitored annually.
External signs of raw materials
Whole raw materials
Whole leaves or pieces.
Purple foxglove leaves has oblong-ovate or ovate-lanceolate form, their edge is unevenly-crenate. Bottom sand leaves with long winged petioles, stem leaves are short-petiolate or without petioles (Fig. 6.3, A). The leaves are brittle, crinkled, strongly hairy on the underside, with a characteristic dense net of strongly protruding small branches of the veins. The length of leaves is 10-30 cm and more, width is up to 11 cm. The colour of the leaves is dark green from above, grayish-green from below.
Yellow foxglove leaves are lanceolate or oblong-lanceolate, with a blunt-pointed tip, with an unevenly pointed edge and rare teeth; bottom sand and lower stem leaves are gradually narrowing to the base in a short winged stem or without a stem. The venation is angulinerved. The length is up to 30 cm, the width is up to 6 cm. The colour is green on both sides.
The smell is weak. The taste is not determined (!). Poisonous!
Milled raw materials.
Pieces of leaves are of various shapes, passing through a sieve with holes of 7 mm diameter. The colour is grayish green. The smell is weak. The taste is not determined.
Grayish green powder is passing through a 0.16 mm sieve.
The smell is weak. The taste is not determined.
Properties and application
Pharmacotherapeutic group. Cardiotonic agent (cardiac glycosides).
Purple foxglove has a multifaceted effect on the body (vessels, vagus nerve, kidney, intestine, central nervous system), but the main object of its action is the heart.
Cardiac glycosides increase systole, prolong diastole, reduce the excitability of the cardiac conduction system. According to modern concepts, the physicochemical mechanism of the action of cardiac (cardiotonic) glycosides consists in changes in the activity of Na-, K-dependent ATPase, an increase in the intracellular content of sodium ions, increasing the entry into the cells of calcium ions directly involved in the contractile act. In addition, under the influence of cardiac glycosides in the blood plasma increases the amount of ionized calcium.
Purple foxglove glycosides belong to lipophilic cardiotonic glycosides. They are strongly associated with blood proteins, so their penetration into the myocardium is slow. With internal use of digitoxin, the cardiotropic effect develops only after 2-3 hours and lasts for 2-3 weeks. The glycosides of the plant while ingested gradually accumulate in the body and have a high degree of cumulation.
Digitonin and other foxglove saponins possess irritating and hemolytic properties.
They help to increase the solubility and absorption of cardiac glycosides.
Application of foxglove
The preparations of purple foxglove are used at circulatory failure II and III stages of different origin, as well as in the tachysystolic form of atrial fibrillation, usually accompanying and aggravating circulatory failure. In case of overdose of foxglove preparations, intoxication phenomena are observed, which are expressed in bradycardia, sleep disturbance increased dyspnea the appearance of unpleasant sensations in the heart.
- Infectious diseases,
- coronary insufficiency,
- heart disease,
- myocardial infarctionб
- period of pregnancy and lactation,
- pediatric use.