Some newer findings on digitalis

Abstract

1) Being treated with ethyl acetate, the extract of the dried leaves of digitalis purpurea is separated into two portions, one soluble and fast in action, and the other insoluble and slow in action. The insoluble portion principally contains purpurea glucosides. The exclusion of saponin-like substances from the insoluble portion mentioned above by ethanolether brings about only a little loss of activity. Presumably only a small quantity of free digitoxin or gitoxin may be contained in the original leaf. The stability of the glucosides is tested. To add butyl-p-hydroxybenzoate is a good method for the stabilization of the insoluble portion. If methanol, n-propyl alcohol, aceton, chloroform, ethyl acetate, and ether are compared in efficiency to the extract of active substances with each other, methanol is the most easily extractable of these solvents, and propyl alcohol and ethanol are less in sequence. 2) The change of temperature seems responsible for seasonal variations of the susceptibility that the heart of frogs shows to digitalis in bio-assay. The difference in the body weight of frogs needs not to be taken into consideration as far as digitalis is injected subcutaneously to them in doses in proportion to the body weight. 3) When digitoxin (U.S.P.), digitoxin (Merck in Germany), digilanid, lanatoside C, and k-strophanthin are compared in action with each other, digitoxin (U.S.P.) is the slowest in its action, lanatoside C and digilanid are next, and digitoxin (Merck) and k-strophanthin follow. The stability of aqueous solutions of the above digitoxin and k-strophanthin is examined by varying pH. It consequently follows that two kinds of digitoxin may differ in quality from each other. (The more detailed descriptions are found in the following reference : Acta Medica et Biologica, Vol. 2, No. 1, 1954.)