Sepn of cardenolides and cardanolides

摘要

Separation of cardenolides from cardanolides and 14,21-epoxycardanolides depends on their differing stabilities to alkalies. Under suitable conditions cardanolides and their epoxy derivs. are saponifiable whereas cardenolides are not. Thus a mixture of digitoxin (250 mg) and dihydrodigitoxin (250 mg) is dissolved in pyridine and carbonate buffer is added. The pH is adjusted to 10.5 with 0.5N KOH and the mixture warmed to 40 degrees. After 15 min. 0.05M carbonate buffer of pH 12.5 is added and the mixture extracted with CHCl3 to give an extract from which 212 mg pure digitoxin is recovered. Extraction of the aq. phase adjusted to pH 3-4 yields 190 mg pure dihydrodigitoxin.