Digitoxin (Molecule of the Month for June 2011)
Digitoxin is a cardiac glycoside. It has similar structure and effects to digoxin (though the effects are longer-lasting). Unlike digoxin (which is eliminated from the body via the kidneys), it is eliminated via the liver, so could be used in patients with poor or erratic kidney function. However, it is now rarely used in current Western medical practice. While several controlled trials have shown digoxin to be effective in a proportion of patients treated for heart failure, the evidence base for digitoxin is not as strong, although it is presumed to be similarly effective. Digitoxin exhibits similar toxic effects to the more commonly used digoxin, namely: anorexia, nausea, vomiting, diarrhea, confusion, visual disturbances, and cardiac arrhythmias. Antidigoxin antibody fragments, the specific treatment for digoxin poisoning, are also effective in serious digitoxin toxicity.
The first description of the use of foxglove dates back to 1775. For quite some time, the active compound was not isolated. Oswald Schmiedeberg was able to obtain a pure sample in 1875. The modern therapeutic use of this molecule was made possible by the works of the pharmacist and the French chemist Claude-Adolphe Nativelle (1812-1889). The first structural analysis was done by Adolf Otto Reinhold Windaus in 1925, but the full structure with an exact determination of the sugar groups was not accomplished until 1962.
Digitoxin is used as the murder weapon in Agatha Christie's Appointment with Death, Elizabeth Peters' Die For Love and CSI, season 9, episode 19: "The Descent of Man". It was also used as a poison in "Uneasy Lies the Crown" on Columbo, season 9, episode 5 (1990), "Affair of the Heart" on McMillan and Wife, season 6, episode 5 (1977) and on Murder 101: "College can be a Murder".
Formal Chemical Name (IUPAC)
(3β,5β)-3-[(O-2,6-dideoxy- β-D-ribo-hexapyranosyl-(1->4)- 2,6-dideoxy-β-D-ribo-hexopyranosyl)oxy]- 14-hydroxycard-20(22)-enolide
Update by Karl Harrison
(Molecule of the Month for June 2011 )