FOXGLOVE

Family: Scrophulariaceae

Genus: Digitalis

Species: purpurea

(i) General background on the plant

Foxglove is a tall downy biennial herb with an unbranched stem reaching 50-150 cm high. Leaves are alternate, ovate-lanceolate, softly hairy. Flowers are produced in a long erect terminal raceme, with a tubular to narrow bell-shaped corolla. Flowers are 4 - 5 cm long, mauve with dark purple spots ringed with white inside. The flowers are pollinated by bumble bees and produce ovoid seed capsules containing numerous tiny, dark brown seeds.

D. purpurea is common thoroughout Europe, especially in woodlands. It is often the dominant plant species when clearings or burnt areas are regenerating. It is a popular garden plant on account of its showy flowers.

(ii) Details of quality characters

The drugs digitoxin and digoxin are obtained from the leaves of this species and used in orthodox medicine for heart disease; they increase the strength of heart contractions and regulate the heartbeat. The compounds were discovered in the common foxglove (Digitalis purpurea), but compounds in Grecian foxglove (Digitalis lanata) are up to four times as potent (Bremness, 1994).

(iii) Current production and yields

(iv) Constraints on production

(v) Markets and market potential

D.purpurea is cultivated commercially as a field crop for the pharmaceutical industry in western (particularly north-west) Europe for the drug digitoxin. Digitoxin is highly poisonous but is used as a cardiotonic steroid used to increase the force of the heart beat to cure dropsy and prevent/alleviate congestive heart failure [2]. The toxicity of the plant is unaffected by drying, storage or boiling.

Digitoxin is a secondary glycoside and is extracted from the dried leaves with 50% alcoholic solution. Acid hydrolysis yields digitoxigenin and digitoxose. 10 kg of leaves yields 6g digitoxin, and a greater amount of the more active digoxin.

(vi) Other information

D. purpurea is also grown as an ornamental.

(vii) Contacts

(viii) References

1. Flora of the British Isles; Clapham, A. R.; Tutin, T. G. & Moore, D. M. (1987)
3rd Edition. Published Cambridge University Press.

2. Biochemistry (1988) Stryer, L. 3rd Edition.

3. Bremness, L. (1994) Herbs; Dorling Kindersley Ltd. London. pp.247.