Foxglove helps against heart failure

Heart medicines are still being extracted from the foxglove, i.e., the species of the genus Digitalis. The foxglove played no significant part within the school medicine during the 17th and 18th centuries. This however changed in 1775 when the English doctor, William Withering, described having observed how a traditional healer from Shropshire successfully treated a case of dropsy with a decoct of foxglove. Dropsy is a form of oedema (swelling) that can be caused by inadequate heart function. This observation triggered Withering to experiment with foxglove on patients with dropsy. In 1785 he published his results in the book ”An Account of the Foxglove, and some of its medical uses: with practical remarks on dropsy.” Ever since then Digitalisleaves have had worldwide success.

The first time a mixture of so called cardio-active glycosides was extracted from the leaves of the foxglove was in the middle of the 19th century. Since then chemical methods have improved and we can now differentiate between the various Digitalis-glycosides and today we are aware of many different ones.

Several of these are registered drugs in Sweden. Very similar substances are also found in the lily of the valley (Convallaria majalis) and in the common toad (Bufo bufo). The lily of the valley is very toxic and the poison consists of various cardio-active substances. Its leaves used to be sold at pharmacies as heart medicine.

Mayapple, Podophyllum peltatum, is a low herb that grows in the woods of Eastern USA and Canada. The plant has a rhizome that can grow up to one meter long. Previously, an extract from the root was produced by using alcohol. The extract was then concentrated and diluted hydrochloric acid was added. Precipitation forms which was washed, dried and subsequently ground to a powder. This powder, which is known in the pharmaceutical world as podophyllum, contains 20% podofyllotoxin, 10% beta-peltatin, and 5% alfa-peltatin.

In early 20th century podophyllum was mainly used as a laxative. Its laxative effects are principally due to the presence of peltatin. Podophyllin was used for venereal warts, but in modern medicine we use podophyllin instead in its refined form, podophyllotoxin. Both peltatin och podophyllotoxin have inhibiting effects on tumours and have therefore been thoroughly studied. Various derivatives of podophyllotoxin have been produced, e.g., teniposid which is mainly used against cancer of the bladder, and etoposid against other types of cancer.

Another species Podophyllum hexandrum (synonymous: P. emodii) is native of the Himalayas. Podophyllin, produced from this species, contains up to 40% podophyllotoxin and no peltatins. Therefore it is much less of a laxative than podophyllin from P. peltatum. P. hexandrum is used today for the refinement of podophyllotoxin for drug manufacture. Modern research has shown that podophyllotoxin is not only effective against cancer but is also useful in the treatment of genital warts and other viral illnesses. Clinical tests have shown that podophyllotoxin or structurally similar compounds have positive effects on other diseases, such as psoriasis, rheumatoid arthritis, Alzheimer and malaria.

Suggested Reading:
Bohlin, L. and Rosén, B., Podophyllotoxin derivatives: drug discovery and development. Drug Discovery Today 1:343-351, 1996.