Pharmacognosy of digitalis

Pharmacognostic study of Digitalis. It includes all the detail of drug.

1. DIGITALIS

2. DIGITALIS Synonyms : Foxglove leaves, digitalis leaves Biological source : It is obtained from dried leaves of Digitalis pupurea Family : Scrophulariaceae It is required to contain atleast 0.3 % of total cardenolides calculated as Digitoxin . After collection from the field, leaves are dried immediately at a temperature not exceeding 60 ֯ C and are stored in moisture proof container.

3. Digitalis purpurea – Purple foxglove

4. Habitat: It is a biennial herb which is grown in England and also cultivated in India, Europe and USA. Cultivation/Collection : It is propagated by seeds. It requires calcareous, acidic, sandy soil for growth. Seeds are very small in size i.e. 100 seeds weigh 40 to 70 mg. Seeds are mixed with fine sand and sown in nursery beds in march/ april . Young seedlings are transplanted in sep/ november . Crop is manured and kept free from weeds.

5. Plantation done twice a year. Plant flowers in the month of april and is followed by fruiting. In the first year plant bears rosette leaves and in second year sessile leaves. Leaves collected in second year in the afternoon during august and September when 2/3 rd of flowers are fully developed . Discolored leaves are rejected. After collection leaves are immediately brought to drying centre and dried in vaccum dryer at a temp. below 60 ֯ C till the moisture is not more than 5%. Dried leaves are packed in air tight container with suitable dehydrating agent. If the leaves are dried above 60 ֯ C the potency is lost due to chemical degradation.

6. Activity of the leaves is due to glycosides. Presence of moisture and enzyme i.e. Digipurpuridase and oxidase cause deterioration. Macroscopy : Colour : Dark greyish green Odour : Odourless Taste : Distinctly bitter Size : length – 10 to 30 cm Width – 4 to 10 cm Shape : Ovate, lanceolate, petiolate

7. Base : Decurrent or dentate Apex : Subacute Margin : Crenate or dentate Surface: Both surfaces are pubescent Microscopy: It is dorsivental leaf It has anomocytic stomata Covering and glandular trichomes on both sides. Glandular trichomes are short, unicellular stalk and unicellular or bicellular head.

8. Covering trichomes are uniseriate with colapsed cells. Digitalis is free from Ca oxalate crystals and sclerenchyma . Starch grains are present. Collenchyma is present.

9. T.S of Digitalis purpurea

10. Chemical constituents: Digitalis contain 0.2 to 0.45% of both primary and secondary glycosides. Primary glycosides- Purpurea glycosides A and B, glucogetaloxin and Secondary are – digitoxin , gitoxin and getaloxin . Primary glycosides are less stable and less significant than secondary glycosides. Purpurea glycosides A and B constitute the principle active constituent of the fresh leaves.

11. Compounds R1 R2 Gitoxigenin H OH Digitoxigenin H H Uses: It is used in the treatment of congestive heart failure.

12. It block the Na-K+ ATPase pump of cardiac muscle Increase the intracellular sodium Increase in calcium ions Result in forceful contraction of myocardium

13. Greater output per beat Complete emptying of heart delayed circulation improved Oedema flush out

14. 2. It increase excitability of cardiac muscle and produce more powerful contractions. 3. The improvement through kidney results in diuresis and loss of oedema. 4. It is effective in congestive heart failure to increase cardiac output and to relieve venous congestion, hence it is used as cardio tonic. 5. The major disadvantage of digitalis is that it has ‘cumulative effect’ so administration of drug should be under strict medical supervision. Prepared digitalis : It is the powdered digitalis prepared from the dried leaves of digitalis. It is an official preparation along with digitalis tablets, digitalis tincture and digitoxin injection.

15. Storage: It should be stored in well closed container in cool place away from light. Leaves do not contain more than 5% of moisture because it causes the destruction of the glycosides and ultimately the loss of cardiac activity on storage . Adulterants: 1. Mullein leaves: Obtained from Verbasum thapsus . It is densly covered with large branched wooly hairs. 2. Comfrey leaves: Symphytum officinale , family Boraginaceae . It can be detected by the presence of multicellular trichome .

16. 3. Primrose leaves : Primula vulgaris , family Primulaceae . It is detected microscopically by the presence of uniseriate covering trichome . Alide drugs: Digitalis Lanata (White foxglove): Syn : austrial digitalis, woolly foxglove leaves. Biological source : Digitalis lanata part used : Dried leaves family : scrophulariaceae

17. Digitalis lanata plant

18. G.S: mostly in eastern Europe and also in Holland and USA. Morphology : Leaves: oblong, lanceolate, sessile with entire margin. Size : length : 21 cm, width is 6 cm Chemical constituents : It is potent than digitalis pupurea and is used as a source for the manufacture of digoxin and other glycosides. Digoxigenin and diginatigenin are specific to digitais while others are present in digitalis pupurea .

19. Chemical constituents: Digitalis lanata Lanatoside A Lanatoside B Lanatoside C (Acetylated PG –A ) (Acetylated PG –B ) -acetate Alk.hydrolysis Deacetyl lanatoside A -glucose Enzymatic hydrolysis Digitoxin Alk.hydrolysis Deacetyl lanatoside B Enzymatic hydrolysis Gitoxin Alk . hydrolysis Deacetyl lanatoside C Digoxin Enzymatic hydrolysis

20. Uses: Leaves are used almost exclusively for the preparation of lanatosides and digoxin . Also used in the treatment of auricular fibrilisation and congestive heart failure. It is preferred because of less cumulative effect.

21. Chemical structure of Digoxin AND digitoxin :

22. Species: Digitalis lutea : It is more potent. It is free from Ca oxalate and it is used as common substitute for official drug Digitalis thapsi : It is spanish variety. It is found in spain and Italy. Leaves can be identified by the absence of non- glandular trichomes . It is 1.25 to 3 times more potent than digitalis purpurea .