Synonym: Foxglove leaves

Biological source:

It consists of dried leaves of Digitalis purpurea

Family: Scrophulariaceae

Macroscopical characters:

• Colour: Dark grayish-green

• Odour: Slight

• Taste: bitter

• Size: 10 to 40 cm long and 4 to 20 cm wide

• Shape: Ovate-lanceolate to broadly ovate; with irregularly crenate or serrate or occasionally dentate margin.

• The leaves are slightly pubescent on both the surfaces with pinnate venation and prominent vein lets on the under surface.

• Generally, the leaves are broken and crumpled.

Chemical constituents:

• Digitalis contains 0.2 to 0.45% mixture of both primary and secondary cardiac glycosides (cardenolides).

• Purpurea glycosides A and B and glucogitaloxin are primary glycosides possessing at C-3 of the aglycone, 3 digitoxose moieties terminated by glucose.

• The primary glycosides are less absorbed and less stable than secondary glycosides such as Digitoxin, Gitoxin and Gitaloxin.

• Odoroside H,

• Gitaloxin,

• Verodoxin, And Glucoverodoxin.

• 2 saponin glycosides, viz. digitonin and gitonin

MOA of Digitalis

• Digitalis increase rest time between two contraction by shortens the length of systole,

• Digitalis blocks the sodium-potassium ATP-ase pump of the cardiac muscle so that intracellular concentration of sodium is increased.

• This cause sarcolemma released calcium ions implies brushing action of proteins viz Actin and myosin is enhanced.

• This is exhibited as more forceful contractions of myocardium, greater output per beat and complete emptying of heart.

• Due to this, the delayed circulation in congestive heart failure is improved and the oedema is flushed out.

• Another major use of digitalis is atrial flutter, supraventricular tachycardia and premature extra systoles.

• This is due to negative chronotropic effect (slowing the heart rate) by directly suppressing the conduction of electric impulses at auriculoventricular node.

Adulterants of Digitalis

Allied Drugs of Digitalis

Chemical test for digitalis

References:

1. Trease D. & Evans W.C.: Text Book of Pharmacognosy: W.B. Saunders.

2. Tyler V. E. Brady L. R. & Robbers J. E.: Pharmacognosy; Lea Feibger, USA.

3. Wallis T. E.; Text Book of Pharmacognosy; CBS Publishers, Delhi.

4. Kokate C. K., Purohit A. P. & Gokhale S. B.: Pharmacognosy; Nirali Publications, Pune.

5. Harbone J. B.: Phytochemical Methods: A guide to modern techniques Analysis: Chapman & Hall, London.

6. Bruneton J.: Pharmacognosy, Phytochemistry, Medicinal Plants: Intercept Limited.