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Foxglove
Digitalis purpurea (Common Foxglove)
Scientific classification
Kingdom: Plantae
(unranked): Angiosperms
(unranked): Eudicots
(unranked): Asterids
Order: Lamiales
Family: Plantaginaceae[1]
Genus: Digitalis
L.
Species

About 20 species, including:
Digitalis cariensis
Digitalis ciliata
Digitalis davisiana
Digitalis dubia
Digitalis ferruginea
Digitalis grandiflora
Digitalis laevigata
Digitalis lanata
Digitalis leucophaea
Digitalis lutea
Digitalis obscura
Digitalis parviflora
Digitalis purpurea
Digitalis thapsi
Digitalis trojana
Digitalis viridiflora

Digitalis (pronounced /ˌdɪdʒɨˈteɪlɨs/)[2] is a genus of about 20 species of herbaceous perennials, shrubs, and biennials that are commonly called foxgloves. The genus was traditionally placed in the figwort family Scrophulariaceae, but upon review of phylogenetic research, it has now been placed in the much enlarged family Plantaginaceae.[1] The genus is native to Europe, western and central Asia, and northwestern Africa. The scientific name means "finger-like" and refers to the ease with which a flower of Digitalis purpurea can be fitted over a human fingertip. The flowers are produced on a tall spike, are tubular, and vary in colour with species, from purple to pink, white, and yellow. The best-known species is the Common Foxglove, Digitalis purpurea. It is a biennial, often grown as an ornamental plant due to its showy flowers, that range in colour from purples through to whites, with variable marks and spotting. The first year of growth produces only the long, basal leaves. In the second year, the erect leafy stem 0.5-2.5 m tall develops. The larvae of the Foxglove Pug feed on the flowers of Digitalis purpurea. Other Lepidoptera species feed on the leaves including Lesser Yellow Underwing.

The term digitalis is also used for preparations containing cardiac glycosides, particularly digoxin, extracted from plants of this genus.

Contents

Medicinal use

Medicines from foxgloves are called "Digitalin". The use of Digitalis purpurea extract containing cardiac glycosides for the treatment of heart conditions was first described in the English speaking medical literature by William Withering, in 1785,[3] which is considered the beginning of modern therapeutics (Silverman)[4][5] It is used to increase cardiac contractility (it is a positive inotrope) and as an antiarrhythmic agent to control the heart rate, particularly in the irregular (and often fast) atrial fibrillation. It is therefore often prescribed for patients in atrial fibrillation, especially if they have been diagnosed with heart failure.

A group of pharmacologically active compounds are extracted mostly from the leaves of the second year's growth, and in pure form are referred to by common chemical names such as digitoxin or digoxin, or by brand names such as Crystodigin and Lanoxin, respectively. The two drugs differ in that Digoxin has an additional hydroxyl group at the C-3 position on the B-ring (adjacent to the pentane). Both molecules include a lactone and a triple-repeating sugar called a glycoside.

Digitalis works by inhibiting sodium-potassium ATPase. This results in an increased intracellular concentration of sodium, which in turn increases intracellular calcium by passively decreasing the action of the sodium-calcium exchanger in the sarcoplasmic reticulum. The increased intracellular calcium gives a positive inotropic effect. It also has a vagal effect on the parasympathetic nervous system, and as such is used in reentrant cardiac arrhythmias and to slow the ventricular rate during atrial fibrillation. The dependence on the vagal effect means that digitalis is not effective when a patient has a high sympathetic nervous system drive, which is the case with acutely ill persons, and also during exercise.

Digitalis toxicity (Digitalis intoxication) results from an overdose of digitalis and causes anorexia, nausea, vomiting and diarrhea, as well as sometimes resulting in xanthopsia (jaundiced or yellow vision) and the appearance of blurred outlines (halos). Bradycardia also occurs. Because a frequent side effect of digitalis is reduction of appetite, some individuals have used the drug as a weight loss aid.

Digitalis is an example of a drug derived from a plant formerly used by folklorists and herbalists: herbalists have largely abandoned its use because of its narrow therapeutic index and the difficulty of determining the amount of active drug in herbal preparations. Once the usefulness of digitalis in regulating pulse was understood, it was employed for a variety of purposes, including the treatment of epilepsy and other seizure disorders, now considered inappropriate.

Toxicity

Digitalis purpurea drawings by Franz Köhler

Depending on the species, the digitalis plant may contain several deadly physiological and chemically related cardiac and steroidal glycosides. Thus, the digitalis has earned several more sinister monikers: Dead Man’s Bells, and Witches’ Gloves.

The entire plant is toxic (including the roots and seeds), although the leaves of the upper stem are particularly potent, with just a nibble being enough to potentially cause death. Early symptoms of ingestion include nausea, vomiting, diarrhea, abdominal pain, wild hallucinations, delirium, and severe headache. Depending on the severity of the toxicosis the victim may later suffer irregular and slow pulse, tremors, various cerebral disturbances, especially of a visual nature (unusual colour visions with objects appearing yellowish to green, and blue halos around lights), convulsions, and deadly disturbances of the heart. For a case description, see the paper by Lacassie.[6]

There have been instances of people confusing digitalis with the relatively harmless Symphytum (comfrey) plant (which is often brewed into a tea) with fatal consequences. Other fatal accidents involve children drinking the water in a vase containing digitalis plants. Drying does not reduce the toxicity of the plant. The plant is toxic to animals including all classes of livestock and poultry, as well as felids and canids.

Digitalis poisoning can cause heart block and either bradycardia (lowered heart rate) or tachycardia (increased heart rate), depending on the dose and the condition of one's heart. It should however be noted, that electric cardioversion (to "shock" the heart) is generally not indicated in ventricular fibrillation in digitalis toxicity, as it can increase the dysrhythmia in digitalis toxicity. Also, the classic drug of choice for VF (ventricular fibrillation) in emergency setting,[7] amiodarone (Cordarone) can worsen the dysrhythmia caused by digitalis, therefore, the second-choice drug Lidocaine is more commonly used.

Use in molecular biology as digoxigenin

Digoxigenin (DIG) is a steroid found exclusively in the flowers and leaves of the plants Digitalis purpurea and Digitalis lanata. It is used as a molecular probe to detect DNA or RNA. It can easily be attached to nucleotides by chemical modifications. DIG molecules are often linked to uridine nucleotides; DIG labeled uridine (DIG-U) can then be incorporated into RNA probes via in vitro transcription. Once hybridisation occurs in situ, RNA probes with the incorporated DIG-U can be detected with anti-DIG antibodies that are conjugated to alkaline phosphatase. To reveal the hybridised transcripts, alkaline phosphatase can be reacted with a chromogen to produce a colour precipitate.

See also

References

  1. ^ a b Olmstead, R. G., dePamphilis, C. W., Wolfe, A. D., Young, N. D., Elisons, W. J. & Reeves P. A. (2001). "Disintegration of the Scrophulariaceae". American Journal of Botany 88: 348–361. doi:10.2307/2657024. PMID 11222255. http://www.amjbot.org/cgi/content/full/88/2/348.  
  2. ^ OED: "Digitalis"
  3. ^ Goldthorp WO (2009). "Medical Classics: An Account of the Foxglove and Some of its Medicinal Uses by William Withering, published 1785". Brit Med J 338: b2189.  
  4. ^ . In contemporary medicine, a purer form of digitalis (usually digoxin) is obtained from Digitalis lanata.
  5. ^ Digoxin comes from Digitalis lanata. Hollman A. BMJ 1996;312:912. online version accessed 18 Oct 2006 [1]
  6. ^ A non-fatal case of intoxication with foxglove, documented by means of liquid chromatography-electrospray-mass spectrometry. Lacassie E et al., J Forensic Sci. 2000 Sep;45(5):1154-8. Abstract accessed online 19 Sep 2006. [2]
  7. ^ "European Resuscitation Council". http://www.erc.edu.  
  • Richard B. Silverman, The Organic Chemistry of Drug Design and Drug Action.
  • Flora of Turkey. Edinburgh University Press.

External links

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1911 encyclopedia

Up to date as of January 14, 2010

From LoveToKnow 1911

DIGITALIS. The leaves of the foxglove, gathered from wild plants when about two-thirds of their flowers are expanded, deprived usually of the petiole and the thicker part of the midrib, and dried, constitute the drug digitalis or digitalis folia of the Pharmacopoeia. The prepared leaves have a faint odour and bitter taste; and to preserve their properties they must be kept excluded from light in stoppered bottles. They are occasionally adulterated with the leaves of Inula Conyza, ploughman's spikenard, which may be distinguished by their greater roughness, their less divided margins, and their odour when rubbed; also with the leaves of Symphytum officinale, comfrey, and of Verbascum Thapsus, great mullein, which unlike those of the foxglove have woolly upper and under surfaces. The earliest known descriptions of the foxglove are those given by Leonhard Fuchs and Tragus about the middle of the 16th century, but its virtues were doubtless known to herbalists at a much remoter period. J. Gerarde, in his Herbal (1597), advocates the use of foxglove for a variety of complaints; and John Parkinson, in the Theatrum Botanicum, or Theater of Plants (1640), and later W. Salmon, in The New London Dispensatory, similarly praised the remedy. Digitalis was first brought prominently under the notice of the medical profession by Dr W. Withering, who, in his Account of the Foxglove (1785), gave details of upwards of zoo cases chiefly dropsical, in which it was used.

Digitalis contains four important glucosides, of which three are cardiac stimulants. The most powerful is digitoxin C34H54011, an extremely poisonous and cumulative drug, insoluble in water. Digitalin, is crystalline and is also insoluble in water. Digitalein is amorphous but readily soluble in water. It can therefore be administered subcutaneously, in doses of about onehundredth of a grain. Digitonin, on the other hand, is a cardiac depressant, and has been found to be identical with saponin, the chief constituent of senega root. There are numerous preparations, patent and pharmacopeial, their composition being extremely varied, so that, unless one has reason to be certain of any particular preparation, it is almost better to use only the dried leaves themselves in the form of a powder (dose a-z grains). The pharmacopeial tincture may be given in doses of five to fifteen minims, and the infusion has the unusually small dose of two to four drachms - the dose of other infusions being an ounce or more. The tincture contains a fair proportion of both digitalin and digitoxin.

Digitalis leaves have no definite external action. Taken by the mouth, the drug is apt to cause considerable digestive disturbance, varying in different cases and sometimes so severe as to cause serious difficulty. This action is probably due to the digitonin, which is thus a constituent in every way undesirable. The allimportant property of the drug is its action on the circulation. Its first action on any of the body-tissues is upon unstriped muscle, so that the first consequence of its absorption is a contraction of the arteries and arterioles. No other known drug has an equally marked action in contracting the arterioles. As the vaso-motor centre in the medulla oblongata is also stimulated, as well as the contractions of the heart, there is thus trebly caused a very great rise in the blood-pressure.

The clinical influence of digitalis upon the heart is very well defined. After the taking of a moderate dose the pulse is markedly slowed. This is due to a very definite influence upon the different portions of the cardiac cycle. The systole is not altered in length, but the diastole is very much prolonged, and since this is the period not only of cardiac rest but also of cardiac "feeding" - the coronary vessels being compressed and occluded during systole - the result is greatly to benefit the nutrition of the cardiac muscle. So definite is this that, despite a great increase in the force of the contractions and despite experimental proof that the heart does more work in a given time under the influence of digitalis, the organ subsequently displays all the signs of having rested, its improved vigour being really due to its obtaining a larger supply of the nutrient blood. Almost equally striking is the fact that digitalis causes an irregular pulse to become regular. Added to the greater force of cardiac contraction is a permanent tonic contraction of the organ, so that its internal capacity is reduced. The bearing of this fact on cases of cardiac dilatation is evident. In larger doses a remarkable sequel to these actions may be observed. The cardiac contractions become irregular, the ventricle assumes curious shapes - "hour-glass," &c. - becomes very pale and bloodless, and finally the heart stops in a state of spasm, which shortly afterwards becomes rigor-mortis. Before this final change the heart may be started again by the application of a soluble potassium salt, or by raising the fluid pressure within it. Clinically it is to be observed that the drug is cumulative, being very slowly excreted, and that after it has been taken for some time the pulse may become irregular, the blood-pressure low, and the cardiac pulsations rapid and feeble. These symptoms with more or less gastro-intestinal irritation and decrease in the quantity of urine passed indicate digitalis poisoning. The initial action of digitalis is a stimulation of the cardiac terminals of the vagus nerves, so that the heart's action is slowed. Thereafter follows the most important effect of the drug, which is a direct stimulation of the cardiac muscle. This can be proved to occur in a heart so embryonic that no nerves can be recognized in it, and in portions of cardiac muscle that contain neither nervecells nor nerve-fibres.

The action of this drug on the kidney is of importance only second to its action on the circulation. In small or moderate doses it is a powerful diuretic. Though Heidenhain asserts that rise in the renal blood-pressure has not a diuretic action per se, it seems probable that this influence of the drug is due to a rise in the general blood-pressure associated with a relatively dilated condition of the renal vessels. In large doses, on the other hand, the renal vessels also are constricted and the amount of urine falls. It is probable that digitalis increases the amount of water rather than that of the urinary solids. In large doses the action of digitalis on the circulation causes various cerebral symptoms, such as seeing all objects blue, and various other disturbances of the special senses. There appears also to be a specific action of lowering the reflex excitability of the spinal cord.

Digitalis is used in therapeutics exclusively for its action on the circulation. In prescribing this drug it must be remembered that fully three days elapse before it gets into the system, and thus it must always be combined with other remedies to tide the patient over this period. It must never be prescribed in large doses to begin with, as some patients are quite unable to take it,intractable vomiting being caused. The three days that must pass before any clinical effect is obtained renders it useless in an emergency. A certain consequence of its use is to cause or increase cardiac hypertrophy - a condition which has its own dangers and ultimately disastrous consequences, and must never be provoked beyond the positive needs of the case. But digitalis is indicated whenever the heart shows itself unequal to the work it has to perform. This formula includes the vast majority of cardiac cases. The drug is contra-indicated in all cases where the heart is already beating too slowly; in aortic incompetence - where the prolongation of diastole increases the amount of the blood that regurgitates through the incompetent valve; in chronic Bright's disease and in fatty degeneration of the heart - since nothing can cause fat to become contractile.


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Wiktionary

Up to date as of January 15, 2010
(Redirected to digitalis article)

Definition from Wiktionary, a free dictionary

See also digitális

Contents

English

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Wikipedia

Etymology

Modern Latin, from Latin digitālis (named with reference to the German common name for the plant, Fingerhut (thimble)).

Pronunciation

  • IPA: /dɪdʒɪˈteɪlɪs/

Noun

Singular
digitalis

Plural
digitales

digitalis (plural digitales)

  1. A genus of herbaceous shrubs of the Scrophulariaceae family, including the foxglove, Digitalis purpurea.
  2. A medical extract of Digitalis purpurea prescribed for heart failure etc.
    • 2001: The ancient remedy digitalis, extracted from the foxglove plant, for example, acts by blocking sodium channels in heart muscle, preventing potentially dangerous overactivity. — Leslie Iversen, Drugs: A Very Short Introduction (Oxford 2001, p. 25)

Translations


Latin

Etymology

From digitus (finger, toe)

Adjective

digitālis m. and f., digitāle n.; third declension

  1. Of or belonging to the finger

Inflection

Number Singular Plural
Case \ Gender M.F. N. MM.FF. NN.
nominative digitālis digitāle digitālēs digitālia
genitive digitālis digitālis digitālium digitālium
dative digitālī digitālī digitālibus digitālibus
accusative digitālem digitāle digitālēs digitālia
ablative digitālī digitālī digitālibus digitālibus
vocative digitālis digitāle digitālēs digitālia

Related terms

Descendants


Wikispecies

Up to date as of January 23, 2010

From Wikispecies

Taxonavigation

Classification System: APG II (down to family level)

Main Page
Cladus: Eukaryota
Regnum: Plantae
Cladus: Angiospermae
Cladus: Eudicots
Cladus: core eudicots
Cladus: Asterids
Cladus: Euasterids I
Ordo: Lamiales
Familia: Plantaginaceae
Tribus: Digitalideae
Genus: Digitalis
Species: D. ferruginea - D. grandiflora - D. laevigata - D. lanata - D. lutea - D. mariana - D. nervosa - D. obscura - D. parviflora - D. purpurea - D. thapsi - D. viridiflora
Nothospecies: D. ×fucata - D. ×fulva - D. ×macedonica - D. ×media - D. ×pelia - D. ×sibirica

Name

Digitalis L.

Vernacular names

Dansk: Fingerbøl-slægten
Deutsch: Fingerhut
English: Foxgloves, Foxglove
Español: Dedalera
Nederlands: Vingerhoedskruid
日本語: ジギタリス
Polski: Naparstnica
Português: Dedaleira/Campainha
Русский: Наперстянка
Türkçe: Yüksük otu

Simple English

Foxglove
File:Digitalis
Digitalis purpurea (Common Foxglove)
Scientific classification
Kingdom: Plantae
Division: Magnoliophyta
Class: Magnoliopsida
Order: Lamiales
Family: Plantaginaceae
Genus: Digitalis
L.
Species

About 20 species, including:
Digitalis cariensis
Digitalis ciliata
Digitalis davisiana
Digitalis dubia
Digitalis ferruginea
Digitalis grandiflora
Digitalis laevigata
Digitalis lanata
Digitalis leucophaea
Digitalis lutea
Digitalis obscura
Digitalis parviflora
Digitalis purpurea
Digitalis thapsi
Digitalis trojana
Digitalis viridiflora

Digitalis is a genus of about 20 species of herbaceous perennials shrubs, and biennals that are commonly called foxgloves. The genus is native to Europe, western and central Asia, and northwestern Africa.

The term digitalis is also used for preparations containing cardiac glycosides, particularly digoxin, extracted from plants of this genus.


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